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SOFiSTiK AG 2011

Tutorial

3D Multi-Storey Office Building

SSD/SOFiPLUS(-X)

Version 2010

This manual is protected by copyright laws. No part of it may be translated, copied or

reproduced, in any form or by any means, without written permission from SOFiSTiK

AG.

SOFiSTiK reserves the right to modify or to release new editions of this manual.

The manual and the program have been thoroughly checked for errors. However,

SOFiSTiK does not claim that either one is completely error free. Errors and omissions

are corrected as soon as they are detected.

The user of the program is solely responsible for the applications. We strongly encourage

the user to test the correctness of all calculations at least by random sampling.

Tutorial - 3D multi-storey office building

Contents i

Contents

1 Preface ........................................................................................................................... 1

1.1 Tutorial Aim ............................................................................................................ 1

1.2 Tutorial Scope ........................................................................................................ 1

1.3 Program Versions .................................................................................................. 1

1.4 Legend for this Tutorial .......................................................................................... 2

2 Description of the Project ............................................................................................... 3

3 Why Use a 3D Model? ................................................................................................... 9

4 From the Structural System to the FEA Model ...............................................................11

4.1 Preliminary considerations ....................................................................................11

4.1.1 Considerations regarding the system ................................................................11

4.1.2 Considerations about loads and actions ............................................................11

4.1.3 Considerations regarding groups ......................................................................13

4.2 Modelling the details .............................................................................................14

4.2.1 Connection walls/ columns – slabs ....................................................................15

4.2.2 Horizontal details...............................................................................................17

4.2.3 Modelling wall pillars .........................................................................................18

4.3 Meshing ................................................................................................................19

4.3.1 General hints for system generation ..................................................................19

4.3.2 Hints for meshing with SOFIMSHC ...................................................................19

5 Workflow in SSD ...........................................................................................................21

6 Tutorial Example - 3D Multi-Storey Office Building ........................................................22

6.1 Create a new SSD project .....................................................................................22

6.2 Define materials and cross sections ......................................................................23

6.3 Graphical input of system and loads with SOFiPLUS(-X) ......................................24

6.3.1 Input of the initial floor in 2D ..............................................................................24

6.3.2 3D Modelling .....................................................................................................36

6.3.2.1 Creating Vertical structural elements .....................................................37

6.3.2.2 Creating upper floors .............................................................................39

6.3.2.3 Creating ground floor vertical elements .................................................42

6.3.2.4 “Modelling” ground floor .........................................................................43

6.3.2.5 “Modelling” support points .....................................................................43

6.3.2.6 Ground floor - supports ..........................................................................45

6.3.2.7 Check system before creation of hinges ................................................46

6.3.2.8 Create hinges ........................................................................................46

6.3.2.9 Defining load transfer T-beams in first floor slab ....................................49


6.3.2.10 Complete roof over staircase .................................................................51

6.3.2.11 Adjust beams in staircase for wind load transfer ....................................53

6.3.2.12 Create named selection sets .................................................................55

6.3.3 Additional loads (free loads) ..............................................................................56

6.3.3.1 Define actions ........................................................................................56

6.3.3.2 Define load cases for wind and snow .....................................................57

6.3.3.3 Cladding loads .......................................................................................57

6.3.3.4 Wind loads .............................................................................................59

6.4 Export/ Checks .....................................................................................................61

7 Index of Figures ............................................................................................................62


Preface 1

1 Preface

1.1 Tutorial Aim

This tutorial is an introduction to 3D modelling using a multi-storey building as an example. It

will guide you through the whole process of building the modell. Focussing on the general

approach of handling a 3D model using the SOFiSTiK software, this example shows you the

analysis according to EC 1 and 2.

Our graphical user interface, the SOFiSTiK Structural Desktop (SSD) will be used as a

command center. It allows you to control pre-processing, processing and post-processing

tasks for the entire SOFiSTiK Software suite. For the system and load generation we will use

SOFiPLUS(-X).

The shown example of a multi-storey office building deals only with the above-ground

construction. The modelling of basements or foundations will not be covered here. Please be

aware that rigid support conditions will be used to simplify the model. This should be

modified for each individual project.

1.2 Tutorial Scope

This tutorial cannot discuss all of the program parameters, nor act as a substitute for the

program module handbooks. Prerequistes for use of this tutorial include a general knowledge

of the basic program features. These are described in the tutorial SSD / SOFiPLUS (Version

2010) - An Introduction (04.09.2009), which can be downloaded from the SOFiSTiK website

Infoportal.

Further information about SOFiPLUS modelling and the SSD can be found in the SOFiSTiK

website Infoportal SOFiPLUS 2010 (28.07.2011) & SOFiSTiK Structural Desktop

(SSD) (13.07.2011) SOFinar series.

1.3 Program Versions

SOFiSTiK 2010

SOFiPLUS-X 2010 or SOFiPLUS 18.1 with AutoCAD 2010 or higher.

http://www.sofistik.com/no_cache/infoportal/?tx_sofistikinfoportal_pi1%5Bperiod%5D=0&tx_sofistikinfoportal_pi1%5BfilterSubmitted%5D=1&tx_sofistikinfoportal_pi1%5BresultSorting%5D=documentType&tx_sofistikinfoportal_pi1%5BdocumentUid%5D=396

http://www.sofistik.com/no_cache/infoportal/?tx_sofistikinfoportal_pi1%5Bperiod%5D=0&tx_sofistikinfoportal_pi1%5BfilterSubmitted%5D=1&tx_sofistikinfoportal_pi1%5BresultSorting%5D=documentType&tx_sofistikinfoportal_pi1%5BdocumentUid%5D=396

http://www.sofistik.com/no_cache/infoportal/?tx_sofistikinfoportal_pi1%5BdocumentUid%5D=476




Preface 2

1.4 Legend for this Tutorial

SOFiPLUS(-X):

Commands that can be called from the command line begin with an underscore (i.e.

_audit).

All other commands are marked with bold letters and the word „command‟ (i.e.

command structural line). These commands are available via the toolbox, the

sidebar or main dropdown menu (command line is also possible, but you need to

know the correct syntax).

If you wish to use the menu, the menu path is indicated using „>‟ for each menu step

(i.e. file>save).


Description of the Project 3

2 Description of the Project

Figure 1: Overview of the building

This tutorial will explain how to build the multi-storey office building model shown in figure 1.

The main structure comprises a number of shear walls, columns, beams and slabs, along

with a shear core (e.g. stair/lift core).

The shear walls and shear core provide the overall stability for the building. Columns, beams

and walls are used to transfer vertical loads to the ground level. A cladding transfers the wind

loads to the floor slabs. This is assumed as a single element from the bottom to the top of the

building and thus acts similar to a continuous beam. It also exerts a vertical load on all floor

slabs.

The building has an overall width of 12.0m, a length of 34.6m and a height of 19.5m. The

concrete walls are of concrete grade C30/37 and reinforcement steel is grade S500B. The

slabs (with T-beams) and all other cross section are assigned a concrete material of grade

C20/25 and reinforcement steel of grade S500B.

The analysis will be done according to Eurocode 2.



Figure 2: Building Floor Plan and Section 1-1 (not to scale)



The data given here is example of wind loading according to Eurocode 1 (EN 1991-1). The

values are for use as an example only and may not conform with the latest code revision.

The following loads shall be considered:

Load Type Load Value

Self weight of the structure Calculated by the software

Cladding 0.50 kN/m

Superimposed dead load (internal partition walls) 1.20 kN/m²

Live/imposed load (offices, halls…) 2.50 kN/m²

Live/imposed load on stairways (floor slab only;

staircases not modelled, staircase loads ignored)

4.00 kN/m²

Snow 0.75 kN/m²

Wind See table below

area cpe q [kN/m²] we [kN/m2]

A -1.2 0.75 -0.900

B -0.8 0.75 -0.600

C 0 0.75 0.000

D 0.8 0.75 0.600

E -0.7 0.75 -0.525

F -1.8 0.75 1.350

G -1.2 0.75 0.900

H -0.7 0.75 0.525

I 0 0.75 0.000

walls

roof

Wind in Global Y direction (on the long side)

** area cpe q [kN/m²] we [kN/m2]

A-1 -1.200 0.65 -0.780

B-1 -0.800 0.65 -0.520

C-1 -0.500 0.65 -0.325

D-1 0.741 0.65 0.482

E-1 -0.465 0.65 -0.302

A-2 -1.200 0.75 -0.900

B-2 -0.800 0.75 -0.600

C-2 -0.500 0.75 -0.375

D-2 0.741 0.75 0.556

E-2 -0.465 0.75 -0.349

F -2.11 0.75 1.583

G -1.31 0.75 0.986

H -0.70 0.75 0.525

I 0,2/-0,2 0.75 -0.150

** Because height>width, wind load area must be divided

over height according to the design code

with change of sign/ direction as required

Wind in Global X direction (on the gable side)

h<

=b

h>

b

walls

roof

walls



Figure 3: Wind Loading in Global Y Direction (shown in WinGraf as filled area and vector)



Figure 4: Overview of Wind Load Areas in Global X Direction (not to scale)



Figure 5: Overview of Load Areas for Wind in Global Y Direction (not to scale)

This is an example only of how wind loading according to EC 1 may be applied in this example. A fundamental knowledge of the relevant design codes is required.


Why Use a 3D Model? 9

3 Why Use a 3D Model?

Before starting with the project, we will first discuss the characteristics of 2D versus 3D

modelling.

2D Modelling 3D Modelling

Workflow for the structure Splits construction into structural members; analyse each member separately

One large, complex model

Input/handling Easy for each member, but often results in many single, independent files

Complex, but only one file for the whole structure

Level of abstraction High Low

Modelling of details Good for modelling details, bad for coherence

Modelling of details not recommended, good for showing coherence

Time for system generation Relatively little Rather more

Changes/updates during the working process

By hand for each member; danger of omitting something; can involveva lot of work

Only once for the entire model

Complexity of model Low High, danger of “black box” effect

Ease of verification (e.g. by hand)

Relatively simple Rather more difficult

Quality of the results Independent of the type of modelling, although more dependent on the quality of the modelling

Global behaviour of the structure

Difficult to predict, imprecise More precise, e.g. redistribution of forces can be shown

Ability to model and show dependencies

Poor Good

Analysis of local stability Easy Difficult

Dynamic analysis (i.e. earthquake)

Difficult/impossible Simple

Time for analysis Relatively low for single components

Rather more; the entire system must be analysed

Recommended type when focus is on:

Localised design (details) Global design (main structural elements)


Why Use a 3D Model? 10

The table above illustrates that each method has its own strengths and weaknesses.

Depending on the task at hand, 2D and 3D models can be used either in a complementary

manner or entirely separately. It is the reponsibility of the engineer to decide which methods

are most suitable for their project. Each method has its own advantages and disadvantages,

and each project has different requirements, therefore the engineer should make an informed

decision taking these into account.

This tutorial will outline the suggested workflow for the creation of a 3-D model of the

described multi-storey building, although it could also be modelled in 2-D.


From the Structural System to the FEA Model 11

4 From the Structural System to the FEA Model

4.1 Preliminary considerations

To preclude (as far as possible) problems during the analysis/design of a 3D structure, we

recommend to start out by planning the structural system before starting to work with the

software. As discussed in the last chapter, it will not be possible to make a design complete

in all its details using a 3D model.

4.1.1 Considerations regarding the system

Your first task should be to make a list of all the design checks you need to perform.

Based on this list you can then decide which components of the structure you should model

and how far these can be simplified. (Note: Model as simple as possible, but as exact as

necessary.)

Next you should check if any of the components can be merged to a single structural

element (e.g. use of a single cross section for columns of similar dimensions).

Performing a preliminary design of the main structural members (e.g. on a simple beam-

model) may save you time during the design process and will provide a reference to check

your results against. It may also help if you are not sure how to model the details. You will

get a feel for the influence of the structural member on the main structure and if it is worth to

model it in detail or if it is sufficient to use a coarser model.

4.1.2 Considerations about loads and actions

Make a list of all actions and loads (see chapter 2 Description of the Project).

Form a concept for the load case numbering. SOFiSTiK recommends using load case

numbers smaller than 1000 for single load cases, since numbers larger than 1000 are used

by default for loadcase combinations. It is useful to divide the load cases into number groups

according to their actions. For the analysis of this building the following load case concept

will be used:



Load case(s) Content

1 – 99 Dead loads

1 Automatically determined self weight

2 Dead load in offices/halls etc

3 Dead load cladding

100 – 199 Live loads on slabs/ roof

101 – 113 Live/imposed loads

200 – 299 Wind loads (with direction)

201 Wind –Y

202 Wind +Y

203 Wind +X; roof +

204 Wind +X; roof -

205 Wind –X; roof -

206 Wind –X; roof +

300 – 399 Snow

300 Snow on roof

Keep your system flexible and easy to modify. Don‟t use consecutive load case numbers only; if you leave some numbers free between sections you will be able to add extra load cases without disrupting the loading concept.

The following table shows the default loadcase combination numbering used by default by

the software.

Number range Load case combinations by default

1100 – 1200 (default) SLS – permanent

1400 – 1500 (default) SLS – permanent (here: nodal displacements)

2100 – 2200 (default) ULS

In some cases the program uses the same loadcase number to save the results of different superpositions. Nevertheless, the description only shows the name of last superposition that has been saved with this load case number. If this isn‟t suitable for your purposes, simply rename the combination.



You may need to give thought to how your loads will be applied. For example, in this case,

we will need to apply wind loading, however there are very few „walls‟ defined to which they

could be applied to. So that the wind load can be applied to each elevation in its entirety,

load distribution areas (LAR) will be used. These enable the user to apply free loads to any

part of the structure, while the program calculates how these loads are distributed onto either

a frame structure or slab edges within the range of the LAR.

Because the LARs can only be defined to apply load onto elements in a maximum of three

groups, we need to consider how to apply the LAR efficiently.

One option would be to apply a LAR to the wall area for each individual storey, distibuting the

load onto the slabs in two groups.

Another option would be to apply a LAR to the entire building elevation, and define „dummy‟

beam elements in a single group around each slab perimeter to which the loads would be

distributed. This is how we will proceed in this case.

4.1.3 Considerations regarding groups

You may ask, “What is the group concept and why should I use groups in my model?”

The group concept is a classification system used by the software to keep your model clear and functional. You can group parts of your structure by similarities, perhaps one group per construction stage, or one group per cross section. If you define your groups in a distinct way you‟ll be able to work in a fast and effective manner. This will allow you to, for example, (de)select groups of structural elements with a minimum of input, apply loads efficiently, analyse/design only particular elements or to set up graphical post-processing tasks with ease.

There is no universal concept for the definition of groups because it depends on the problem

that has to be solved. In one case it may make sense to define all walls in one group and all

slabs in another, while in another case it might be more effective to group the elements by

floor level.

Using SOFiPLUS-(X), the group-divisor number is the same for all groups. Using the default setting of 10000 (ten thousand) you can define up to a maximum of 999 groups.

Generally speaking, the group number multiplied by the group-divisor should equal less than 10000000 (ten million).



The group divisor defined the maximum number of (finite) elements allowed in one group (quads, beams, springs, etc).

The element number of the finite elements consists of the group number (1st part) and the element number (2nd part). For example, if the group divisor is set to 10000, the finite element number is 345 and the group number is 23, the element number will be 230345).

The following table shows how the elements in this example are classified into groups:

Component Formula for group number

Slabs/roof Level number x 100

e.g. 1st floor group number = 1 x 100 = 100

Columns

(assuming not more than 50

different cross sections)

Cross section number + Level number x 100

e.g. column with cross section 1 on ground floor:

group number = 1 + 0 x 100 = 1

exception: all dummy beams are in group 49

Beams Same group number as the respective slab number

i.e. T-beam in slab of 1st floor: group number =100

Walls

(assuming not more than 50

different walls on each floor)

50 + level number x 100 i.e.

Wall at 3rd floor:

group number = 50 + 3 x 100= 350

4.2 Modelling the details

Although the primary purpose of a model may be to model the realistic behaviour of a

structure, it is important to keep your model as simple as possible. It is worth spending some

time thinking about the details to avoid mistakes and to create the most efficient model.

Building a rationalised model with fewer elements can not only save a lot of calculation time

but will also help you to understand the results.

Modelling details is dependent not only on the specifics of the FEA, but also on the

construction sequence and good engineering practice. In the following, some details and

decisions for the multi-storey office building will be discussed.



4.2.1 Connection walls/ columns – slabs

The following comments are made regarding walls, but in general they are also relevant for the connections between column and slab.

There are basically two possibilities for modelling the connection between walls and slabs:

a) Rigid connection

b) Hinged connection

For the input of the model it is much easier to choose a rigid connection because this is the

default setting in SOFiPLUS(-X). However, you should consider this effect when planning the

reinforcement.

If using a hinged connection there is no analytical bending moment between the slab and the

wall, therefore planning and building the reinforcement is much easier.

The true structural behaviour is somewhere between cases a) and b). Thus, it is the

responsibility of the structural engineer to decide how the connections should be modelled.

Table 1 (Vertical Modelling Details on page 16) and Table 2 (Vertical Modelling Details on

page 17) show which decisions were made for the multi-storey office building in this tutorial.



Figure 6: Overview of Vertical Connection Details

Description (Refer to Figure 6: Overview of Vertical Connection Details)

Case 1: Exterior wall:

Wall is effectively continuous from ground to roof, no hinges. Roof slab connected

with a hinge.

Central axis of wall is moved to the real borderline of the building, meaning that the

wall elements in the model have their nodes in the centre of their thickness. The

walls are moved outward very slightly (conservative).

Case 2: Interior wall:

Wall is effectively continuous from ground to roof, no hinges. Floor slabs connected

to walls with a hinge.

Case 3: Floor slab to exterior wall:

Hinge in the floor slab at connections to walls.

Case 4: Interior/core wall to slab

Floor slabs hinged at connection to interior walls. Walls are continuous.

Case 5: Columns:

All columns modelled with pinned connections where they meet slabs or supports

Floor slab acts as continuous beam through

Table 1: Vertical Modelling Details – Connection of Walls/Columns to Slabs/Roof

1

3

2

4

5



4.2.2 Horizontal details

Figure 7: Overview of Horizontal Modelling Details

Description

Case 1: Exterior wall considering real slab dimensions/mesh:

To avoid kinks in system lines (which do not really exist) and singularities in the

mesh, the system line of the wall is set to the boundary of the slab (instead of 1/3 line

of the wall)

Case 2: Interior wall:

System line = middle line of the wall

Case 3: Interior walls around openings:

Avoid kinks in the system line by choosing the centre line of the wall to the right of

the „lift‟ opening

Other walls modelled using Centre Line command

Case 4: Column support:

Model as a single structural point (with input of dimensions for punching checks)

Case 5: Downstand beam:

Downstand beams are modelled within the slab using a structural line with beam

properties. Any duplication of structure (i.e. due to beam flanges within the slab

depth) is dealt with automatically by the software. Refer to SOFiSTiK − T−Beam

Philosophy in the ASE handbook. For more information.

Table 2: Horizontal Modeling Details

1 2

3

4

5



Another typical case is the situation where a column is located close to the border of a slab

but not directly on it, i.e. the extent of the column lies in line with the slab edge and the center

point of the column is within the slab. In these cases it is better to model the column with its

centre point on the boundary, which will result in a better FE mesh. The minimal increase in

span width can usually be considered negligible.

Figure 8: Modelling Edge Columns Close to Slab Edges

4.2.3 Modelling wall pillars

For the modelling of wall pillars, i.e. sections of wall that may be wider than standard column

dimensions, you should decide whether it is better to model a column using beam elements

or quad elements in each case. This will depend on the system and the applied forces; thus,

no general solution can be recommended for this.

The problem is not only in the design of the wall or column, but also (depending on the

model) in the perfomring other checks for the adjoining slab, particularly regarding punching

design.

Using beam elements might seem easier for the design of the wall pillar but, where the

column dimension ration width:depth>2, the distribution of the forces might not be realistic. In

addition, the large point load caused by the beam element is a singularity and will result in

high localised moments in the slab.

On the other hand, if a small wall is modelled with quad elements you will have to check that

the punching areas do not overlap, because the program might integrate the forces of the

wall ends twice and produce an overestimate in the reinforcement design.



Figure 9: Comparison of Wall Pillar Model Results

4.3 Meshing

Normally the meshing will be done automatically by SOFiMSHC. Nevertheless meshing is

still influenced by the user because all conditions are user defined, thus the quality of mesh

(and results) depends on the mesher and the quality of the model.

4.3.1 General hints for system generation

Define the group divisor as small as possible (see chapter 4.4 of the SOFiMSHC

handbook for more information)

If possible, use elastic supports to avoid singularities

Don‟t model in too much detail; you may generate an excessive amount of elements

with long calculation times, but not necessarily better results

Create your system with identical attributes for all elements at first, then modify them

gradually afterwards while performing regular export/calculation checks.

4.3.2 Hints for meshing with SOFIMSHC

Define intelligent boundary conditions; e.g. insert radial structural lines to assist the

mesh generation on edges with angle >90°, or to define a finer mesh in particular

locations.

Use features such as the column macro (This refines the mesh around a column if a

structural point is not placed upon a structural line, i.e. placed within a slab area).

Define the actual dimensions of the column head within the structural point dialogue,

which will help avoid punching design problems. For further information, refer to the

Punching Checks chapter in the BEMESS handbook.



Place your model near the drawing origin point (0,0), i.e. do not use the Gauss-

Krueger coordinate-system or similar. Placing the model at a location with large

coordinate values reserves a large number of digits which can cause computational

inaccuracies if calculating a system with small dimensions.

If you need a finer mesh, refine the model locally first (e.g. by setting an area mesh

density or assigning a max edge length to structural lines) before decreasing the

Mesh Density in the Export dialogue. This will help to keep the elements in the

drawing and the calculation time to a minimum.


Workflow in SSD 21

5 Workflow in SSD

1. System definition with the System Information task

2. Define Materials

3. Define Cross Sections

4. GUI for Model Creation (SOFiPLUS-(X)) task

5. Define Combinations

6. Linear Analysis

7. Define Superpositioning (if necessary)

8. Compute Superpositioning

9. Design Parameters of area elements

10. Design ULS - area elements

11. Design SLS - area elements

12. Design ULS – Beams

13. Design SLS – Beams

14. (Further tasks e.g. for 2nd order theory analysis – not part of this tutorial)

15. Create results documention (not part of this tutorial)

Because working on a project is an iterative process, it is likely you‟ll need to change something in your project. After you‟ve made your changes, you should then rerun the system from the changed task until the end.


Tutorial Example - 3D Multi-Storey Office Building 22

6 Tutorial Example - 3D Multi-Storey Office Building

6.1 Create a new SSD project

To make the input of this model easier, start with a 2D system and change it at a later stage

to a 3D system.

Select the option “Graphical Pre-processing” in the System Information dialogue. Note that

you can set the units you want to work with in SOFiPLUS. Check that units and the selected

coordinate system correspond with any referenced drawing.

Figure 10: System Information Dialogue

If you wish to use an existing drawing (e.g. architectural plan), ensure that the name of the database given in the System Information dialogue is the same as the [drawingname].dwg, otherwise a new empty *.dwg with the name of the database will be created.



6.2 Define materials and cross sections

Define the materials and cross sections you need for the project:

Number Kind of cross section Concrete Nr. Reinforcement

1 Rectangle 1 S500 two-sided

2 Circle 1 S500

3 T-beam 1 S500 two-sided

Figure 11: SSD Tasktree - Materials and Cross Sections

Materials and cross sections can be added and modified later.



6.3 Graphical input of system and loads with SOFiPLUS(-X)

6.3.1 Input of the initial floor in 2D

Double-click on “GUI for Model Creation (SOFiPLUS(-X))” to open SOFiPLUS(-X) and the

*.dwg with the architect‟s plan. If no drawing is found with the same name as the database, a

new empty drawing will be created. After opening SOFiPLUS(-X), you may need to open and

confirm the system information again.

Before starting to work, you should check where the origin of the coordinate system in the

architect‟s plan is. If it is not yet in one of the corners of the slab, please move the entire

geometry to the origin point by selecting all with Ctrl+A and using the AutoCAD command:

move. This will not only make work easier, but also prevent large numbers for the

coordinates which can cause calculation problems (see chapter 4.3.2). Also, if the model is

too far from the origin, problems may occur with the export and further calculation.

Create the system lines for the ground floor plan with the commands command: Copy to

structural Layer and command: Center Line from the draw menu or the sidebar.

Select the gridlines, the wall lengths and the slab boundaries, including those around the

shear core.

Ensure that all system lines are defined on the layer X___AUFL (SOFiPLUS(-X) Layer for system lines).

Note that system lines are not equivalent to structural lines! System lines are used only as help lines for creating structural elements.

Your system lines should resemble those in Figure 12. Tidy up the lines, e.g. using the

stretch/extend commands and AutoCAD element grips.



Figure 12: Ground Floor Plan with System Lines and Axes

You can also define grid of axes (gridlines) here in the same positions as in the original

drawing. Use the Axis Raster command and enter the information as in Fig 13.

Figure 13: Axis raster command dialogue

Select the Insertion point at the bottom left by clicking on the preview window, click OK, then

select the point of intersection between gridlines A/1. Press enter to confirm without rotating.

Next, switch off all layers except the one containing the system lines (X__AUFL).



Figure 14: X___AUFL Layer Containing System Lines

From these lines, you can now start to create the structural elements, starting with the

structural lines that will represent elements on the slab boundaries and beams.

The purpose of this tutorial is only to demonstrate ways to work efficiently. The procedure outlined here is a recommendation only. There are many other ways to achieve the same result.

Command: Structural Elements - Line

We will now insert some structural lines/dummy beams to the slab edges. (There would

normally be no need to create beams at these locations, however these are needed because

of the following reasons: In the group strategy decided earlier, the slab at each storey will be

assigned to a different group number. In this project that means that there will be five slab

groups in total. Later on, we will use Load Distribution Areas (LAR) to apply wind loading to

the „cladding‟, which will be described later in more detail, however it is important to note now

is that the LAR command can apply loading to a maximum of three groups only. Therefore

we will define some beams at each level and assign them to the same group which the load

distribution areas will apply to.)

Open the Create Structural Element Line command, then right click on the drawing area.

Select “pick lines or curves” selection method from the menu. Select each of the required

boundary lines. When have finished the selection, close the command. Note that if there are

multiple lines in the same place, the program will ask you which one to select.

Don‟t worry if your structural lines are made up of more than one element. They will be

interpreted by the program as continuous through the join unless defined otherwise.



Intermediate nodes will be automatically created by the program where they intersect with

other elements.

Figure 15: System with Structural Lines (WinGraf Plot)

Because the facade will not be modelled, you will use load distribution areas (called LARs) to apply the wind loads onto the structure. LARs act on beams and the edges of slabs, therefore you do not need to create beams along the outside edges of the slabs.

The load distribution areas apply the free area loads (wind loads) onto the system. The free loads are automatically converted into equivalent beam/line loads during the export to .cdb. The LARs act like a layer of quad elements with no stiffness. Refer to chapters 3.16 & 9.3 of the SOFiLOAD handbook for more information.

Command: Cross Sections

First select all the structural lines on the slab boundary using the Modify Structural Line tool ,

then right click when the selection is complete. In the dialogue that appears, open the

“General” tab and change the group number (in this case to 49) to have all dummy beams

within one group. This is important, because later you have to tell the LARs on which group

they will act.



Then open the Beam/Cable tab and select the centric beam type. Then click on the “…”

button to the right of the Cross Sections area.

Define a new rectangular cross section with nearly no stiffness (very small cross section). Fill

in the data shown in Figure 16. Close all dialogues with the OK button.

Figure 16: creating cross section for dummy beams

Click on the “General” tab and change the group number (in this case to 491) to have all the

dummy beams within one group. This is important because you will later need to tell the

LARs on which group they will act. Confirm your input with OK.

1 Number 49 because the highest group number for cross sections is 50; so 49 is a free number and

not used for “real” cross section groups



Figure 17: Assign dummy beams to structure lines

Before we start with the creation of structural areas, the first loadcase for the self-weight of

the structure will be defined. Further loadcases will be created during the structural area

creation.

Command: Loadcase Manager

Open the Loadcase Manager. In the Actions tab, you will see that “dead load” and “live load”

actions are already created. Change to the Loadcases tab and created a new loadcase for

the G dead load action. Set the “SW” factor for this loadcase to 1.0, which instructs the

software to automatically calculate the self-weight of the structure with a factor of 1 using the

geometry of the model, its cross sections and assigned material values.



Figure 18: Loadcase Manager

You can create all necessary actions and loadcases at the same time according to your loadcase strategy using this command. However you can create, modify or delete loadcases later from within the loading commands.



Command: Structure Area

In this case we will separate the floor slabs into discrete areas. They could be modelled as a

slab over entire floor area; however by separating them, it is easier to assign the imposed

loads for different areas, and also assists with the superpositioning for worst case loading.

The joins between them will be considered as continuous, unless otherwise specified.

Open the Create Structural Areas command. On the tab “General” enter all the data as

shown in Figure 19. In the Meshing tab, select the option “Create regular mesh (if possible)”.

Then right-click in the drawing area and choose the selection method “Point in area” and

click into the first slab area.

Figure 19: Creating a Structural Area

The option “Point in area” for the command “structural area” can be used for any enclosed area in 2D systems. In 3D-systems it is only available for use in enclosed areas in the current XY plane of the drawing.

A dialogue called “Loads for Structural Area 1” will automatically appear. For the Permanent

Load, loadcase 1 is already selected. In this case, we want to keep the superimposed dead

load separate to the structure self-weight (which is defined in loadcase 1), so a new loadcase

needs to be created. Click on the “…” button to open the Loadcase Manager. Create and

select load case 2 using action G for the dead load. Then insert a load of 1.2 kN/m² as the

load (which will be applied in the gravity direction).



Do the same for the imposed load. The loadcase number will be 101, action Q, load of 2

kN/m². To select your own loadcase number in the loadcase manager, untick the “Increment

loadcases automatically” option.

Then, when back in the loading dialogue, ensure that the options “Auto increment loadcases”

and “Show dialogue only once“ are de-selected before confirming your input with OK.

This automation for the load cases is only available if you click into the structural area first (and not on the load button).

Figure 20: Loads on Slabs

The command “Structure Area” is still active (the dialogue is still open, and you can check

the command line to see that Sofiplus(-X) is waiting for further input). Now you can create all

other structure areas with the same properties simply by clicking in all areas. You should

create a new loadcase number for each of the area imposed loads , i.e. lc 102 for area 2 and

so on.



Using the the “Auto-Increment Load Cases” option will created a new loadcase automatically but it will select the next unused number closest to zero, so it‟s not suitable for use in this input. When used, the automatically generated loadcase numbers should be check to ensure that they correspond with your loadcase plan.

Note that the imposed load on the slab of the stairway should be 4kN/m² instead of 2.5kN/m².

Loading of areas in this manner is available only in 2D systems. It is not available in 3D systems, which is why it makes sense to start in a 2D system then change the file later on to a 3D system. This allows you to easily copy the floor loads to the upper levels.

Since loads that are defined on the structure areas of this floor will be copied to all other floors, fewer loadcases are required which will result in less load combinations, assuming that the loading distribution will be the same on all floors.

Figure 21: System with Structure Areas and Corresponding Loads

Alternatively, you could use the structural opening tool to create openings for the stair/lift wells. If a structural area is defined right up to the building perimeter, a structural area opening can also be defined within it right up to the edge of the slab.

Any loads that are applied to structural areas with openings will be omitted in the areas where openings are applied.



Command: Structural Point

Next, you should define structural points at those places where there will be columns in the

3d-model. For punching shear checks and design in slabs, the perimeter of the columns will

be defined in the Structural Point dialogue.

Switch on the layers 0 and T_ACHS. Select the command Create Structural Point and enter

data for the circular section columns as follows:

Select the nine locations on the intersections of axes 1 & 3 with A-E excluding A1. Do the

same with the respective perimeter information for the six square section columns along axis

2, including F2. Close the command. Switch off the two layers X_AUFL and 0.

Figure 22: Defining structural points for columns



Command: Export

The input for the 2D-system is now finished, so the next step is to check your file for errors

by exporting it to the CDB (.cdb database file) before changing to a 3D-system, which should

also be done regularly.

Export the system using the default settings so that you can check for any errors in the input

and correct them as they become known. Any errors, warnings or other information will be

displayed in the Log tab of the SOFiPLUS sidebar.

The Export command exports the system to the SOFiSTiK-database *.cdb and runs an

automatic mesh generation program. Usually you do not have to make adjustments and can

use the default settings. After export you should check your 2D system and its mesh in the

ANIMATOR.

Remember also to save your file at regular intervals.

Figure 23: Generated mesh of first floor



6.3.2 3D Modelling

Command: System Information

To start modelling the walls and columns, change the system information in SOFiPLUS(-X)

from 2D slab to 3D FEA.

Figure 24: Change system information



For the 3D-system it may be useful to use multiple viewports simultaneously. For example,

go to Menu View > Viewports > 3 viewports and choose “right”. Click on viewport 1 and,

using the AutoCAD “View” toolbox, change the view to “top”. Click on viewport 2 and change

the view to “left”. Finally click on viewport 3 to set the view to “SW isometric”.

Figure 25: Workspace with 3 viewports; numbers of viewports

6.3.2.1 Creating Vertical structural elements

Command: Structural Line

The columns for the full height of the building will be created in single storey height sections.

Hinges will be applied later to define the end conditions of the columns at each floor level.

Recommended: Create your structure in separate storey heights. Any vertical elements modelled in the same position will be created continuously through the join unless otherwise specified with hinges.

Create your project without hinges to begin with. Once the export is successful, and a test structural calculation has been run to confirm the stability of the structure, you can then start to introduce hinges to the system a small amount at a time while performing calculation tests to check for instability that may have been introduced.

Change to the Iso view (e.g. _swiso). You can also use the Orbit command (_3dorbit) to alter

the view for easier 3D working. Also ensure that the AutoCAD Polar Tracking facility is turned

on. You may find it difficult to select snap points when using the Iso view. If so, use the _orbit

tool to change the aspect slightly.



Select the Create Structural Line command. Enter group 101 and the name “1st floor

columns” in the General tab. In the Beam/Cable tab, define a Centric Beam and select cross

section number 1 for the start and end. Select a start point at a column location in the plan.

Using the polar tracking, move the mouse in the global Z direction and define a height of

3.5m for the input and press enter to confirm. You can then use the copy command (_copy)

to duplicate this column to all column locations. The number of copied elements will be

automatically incremented.

For all columns with the circular cross section, use the modify structural line tool to select the

relevant lines, then right click to confirm the selection. Modify the cross section and group

number in the dialogue, then click OK to confirm the changes. Export to test and view results

in the ANIMATOR.

Command: Wall

As with the columns, the walls that run the full height of the building can be created initially in

single storey heights. They could also be modelled all the way from ground to roof levels.

There would be no user defined joins, however the program will automatically mesh the

areas with any other elements they intersect. If hinges are required at a location in the

height, the wall area can be divided using the Spilt Structural Area command.

You should note that Walls are almost identical to Structural Areas. The only differences are that walls are created in a different plane and an additional option for the definition of a wall height will appear in the Sidebar.

For more information on defining walls, refer to the SOFiSTiK SOFinar titled “SOFiPLUS 2010 Part 2: System Generation 3D – Concrete Structure with SE 17.03.2011” available for download from the SOFiSTiK website Infoportal.

Open the Wall command and enter the correct group number and wall thickness. Select

„Create Regular Mesh (if possible)‟ in the Meshing tab. In the sidebar Opt tab, enter a wall

height value of 3.5m. Right click on the drawing and choose the “Pick lines or Curves” or

“Pick points” selection methods as required. Select the lines that represent the lengths of the

walls, amending the dialogue group and thickness information where necessary.

Command: Opening

Door openings will now be created in the internal walls. Using the geometry lines from the

X_AUFL layer, select an end point for the first point of the opening and use the polar tracking

to select a second point 2.2m above. You can then define the width of the top of the opening,



and the further points of the opening, using the polar tracking or the object snap tracking

(activate using buttons at bottom of user interface). Close the opening by clicking on the first

point again, or by selecting Enter from the right

click menu.

Command: audit

In the command line type _audit and then confirm

the question with y(es). The drawing will be

examined and some detected errors will be fixed.

6.3.2.2 Creating upper floors

Command: _move

The first floor structural elements can now be moved from their position at Z=0 to their final

position at +5.5m in the Z direction. Check that layers 0, T_ACHS and X_AUFL are switched

off. Call the Move command, then select all structural elements and select a base point at

Z=0, e.g. the bottom corner of a wall, and move using the polar tracking to a position 5.5m

directly above.

Figure 26: Original floor moved to first floor level

Command: _copy

Next you can copy the entire initial floor system to all other floors. To do so, use the

AutoCAD command: copy. Select all structural elements at the first floor level and specify a



base point, e.g. the bottom corner of a wall. Then copy upwards to points at the top corner of

the same wall, or use the polar tracking to directly enter a distance. Close the command by

pressing the Enter key.

Figure 27: First floor copied to all other levels

To create the roof slab, select the front view then select only the floor elements (using a left

to right selection box) from a single level, change to an iso view (or use the _orbit command

to change the view) and copy them to the top of the model.

Command: Modify Structural Area

Select all roof area elements and change to the Loads tab. Click on the Edit Structural Area

Default Loads button and modify the permanent and imposed loading and loadcase

according to the loadcase plan. Create a new loadcase 300 for the snow load. We will modify

the loadcase‟s action later on in the Additional Loads section.

Export the model to check for problems in the ANIMATOR.

In the ANIMATOR Control Panel, change to the View Control tab and select the option:

Colour Options > Change of Colour > per Group

This allows you to check the group numbering of structural elements. You can see that the

group numbering has been copied to each level, which now needs to be changed.




With a front view, using the modify structural area command, you can easily select the

second floor slabs using a left to right selection box over the floor level. Change the name of

the structural areas to 2nd floor and the group number to 200 as shown in Figure 28. Modify

all other floor slabs at other levels similarly. Export, then view in ANIMATOR to check. Each

level‟s slabs should now be displayed with a different colour.

Figure 28: Modify structural areas

Command: Modify Structural Line

Open the Display Groups tool. In here, switch off all area groups. Shift+click or Ctrl+click will

allow you to select multiple groups. Only the structural lines and openings will remain.

Openings can‟t be switched off via the Display Groups tool, but their layer

X???ISHO_ASDWG (where “???” represents the group number they‟re assigned to) can be

switched off in the layer manager if required.

In the Left view, open the Modify Structural Line tool and select the centre set of second floor

columns (with the square cross section) using a right to left selection box. Change the name

of these structural lines to 2nd floor and the group number to 201. Modify the name and group



number for the circular section columns. Then repeat for all other floors similarly. Export for a

visual check in ANIMATOR.


Using the Display Groups tool, turn off all structural line groups and switch on all area

groups.

Using a Front view, select the wall areas using a right to left selection box over the area

between the floor levels. Change the name of the structural areas to 2nd floor and the group

number to 250. Change the naming/group numbering similarly for other wall elements.

6.3.2.3 Creating ground floor vertical elements

Command: _copy

Select a Front view and select the relevant vertical elements at 1st floor level. Change back to

an Iso view. Copy all elements directly to the underside of the 1st floor elements using a

vertical element for reference. You will see that the elements are not long enough to reach

the ground floor level.

Change again to a front view and use the _orbit command to rotate the display slightly so

you can select points on the elements more precisely in 3D while the command is open. Call

the _stretch command and select the bottom points of all elements that need to be stretched,

walls, columns and openings all together. Right click to confirm the selection. Select a base

point and stretch the elements 2m downwards.

Figure 29: Stretch view and selection box



Any vertical elements that are not required can be deleted using the _erase command so the

system resembles the below, shown in 3D visulisation mode.

Figure 30: Ground floor elements with applied visual style

The door openings will now be too high. Select one and use the top centre grip to alter the

height. Repeat for the other.

You should then assign the correct group number to the new ground floor columns/walls

according to chapter 4.1.3 Considerations regarding groups.

6.3.2.4 “Modelling” ground floor

In this example, a bottom plate (or ground floor slab) will not be modelled. So that the wind

loads can be applied to the structural system correctly, the dummy beams previously created

should be copied to the ground floor and used for the Load Distribution Area to act onto.

6.3.2.5 “Modelling” support points

Command: Create Structural Point

To facilitate creating point supports later on, we will now create structural points at the base

of each column. Use the create structural point command to place a point at each location.

No settings are defined in the Structural Point dialogue.



Command: Create Structural Point

To facilitate creating line supports later on, we will also create some structural lines at the

internal wall bases. Switch off all the layers except X_AUFL. Use the internal wall lines to

create Structural Lines along each wall location. No settings are defined in the Structural Line

dialogue.

Command: Display Selection Set

In the Front view, open the Display Selection Set command and select the 1st floor level floor

elements using a left to right selection box. Then select all displayed elements again, and

open the Quick Select option in the right click menu. From there, select the dummy beams

(structure lines, group 49).

Command: Copy

Copy selected dummy beams to the ground floor using a base point at first floor level a

distance of 5.5m with the polar tracking.

Figure 31: 1st floor and ground floor with dummy beams



6.3.2.6 Ground floor - supports

As mentioned before, the foundations will not be modelled and the supports are assumed to

be rigid. For the purposes of this tutorial this is OK, however in reality this is not usually a

sufficient assumption.

Command: Modify structural line

Select all lines on the ground floor and select PXX, PYY and PZZ on the tab “Support

conditions”. Because the wall elements are supported by these lines, and because these

lines have no moment support defined (MXX, MYY and MZZ support conditions are not

switched on), no hinge is required at the wall bases to make hinges in the MXX, MYY or MZZ

directions, as discussed on the next page.

Figure 32: Support conditions – structural lines

Command: Modify structural point

Select all points on the ground floor and select PXX, PYY and PZZ on the tab “Support

conditions”.



Figure 33: Support conditions – structural points

Command: Display All

To undo the command Display Selection Set and return all elements to the display, click on

the “display all” command. Export and check the system.

We strongly recommend using the _audit command every now and then to check (and repair if possible) the input for errors. Alternatively for using the command line, you can call the command in the menu File > Drawing Utilities as well.

6.3.2.7 Check system before creation of hinges

As this point, a trial export and calculation is recommended. The structure is nearing

completion but still requires definition of hinges for the column elements and the wall/slab

connections. Before introducing any hinges, the project should be exported to the CDB, then

opened in the SSD using the button in the Sidebar. The Linear Analysis task can then be

used to run a calculation using the self-weight of the structure only. This allows the user to

check if any instabilities have been modelled. Any warnings or errors should be noted and

acted upon if necessary.

6.3.2.8 Create hinges

Command: Modify Structural Line

To model the columns with a hinged connection to the slabs, select all the columns for

editing, then select MY and MZ on the tab “beam hinges” for both the start and end of beam.

It may be helpful to switch off the area elements using the Display Groups command for the

selection. Afterwards, export and run the trial calculation again to check for stability issues.



Figure 34: Beam hinges

On the bottom of the window “structural line” the number next to the question mark tells you how many elements are selected.

Figure 35: Quick graphical check of column hinges

Number of selected

elements



Command: Edit Properties of Boundary Edges of Structural Areas

Select the edge of one or more slab areas where hinges are required, referring to section

4.2, then right click to confirm the selection. In the dialogue that appears, tick the phi-x hinge,

which releases the x-x local degree of freedom. In other cases, you can refer to the local

coordinate system displayed in the drawing for the selected edge to help you choose which

hinge should be selected. It may be useful to turn off the wall groups to make selecting the

slab easier.

Once some hinges are created, export the system and run a trial linear analysis to check for

stability issues. Continue to create all other hinges as required, referring to the connection

details in section 4.2, and run a test calculation periodically.

Figure 36: Hinges (or kinematic constraints) at slab/wall intersections

Make an export and check the system with animator. There you can see that the hinges

(yellow symbols) are visible at the define locations.

The selected edge is shown with a dotted line to give you a visual feedback while defining the hinges.



Figure 37: Check system with ANIMATOR

6.3.2.9 Defining load transfer T-beams in first floor slab

The slab above the ground floor is stiffened with t-beams.

Command: Display selection set

Next, we will create the transfer beams in the first floor slab over the spans where columns

are not present. Select the 1st floor in viewport 1.

Command: Create structural line

Open the command. In the tab “beam/ cable” choose “Centric beam” and assign cross

section number 3. Draw structural lines on axes 1 and 2 between the columns on axes A and

E. Do the same on axis 3, but connecting the beam to the wall adjacent axis 3.



Figure 38: 1st

floor T-beams


Select the structure lines on axis 1 and 3 A-E (start on axis 1 from wall 1).

Because these T-beams are at the edge of the slab, you cannot use cross section number 3

because the flange is too wide. You will need to create a new cross section with a width of

1m only. This can be done when selecting the cross section in the edit structural lines

dialogue. Use the buttons “copy” and “modify” to create this new cross section, then modify

its properties.

Figure 39: Create new cross section for edge T-beams



Command: Display all

After export you can check the T-beams in ANIMATOR.

Figure 40: System with T-beams

6.3.2.10 Complete roof over staircase

Above the staircase a part of the roof is still missing.

Command: Display selection set

Select the roof in viewport 1.

Command: Create structural area

To fill in the area of roof missing over the stair core, you could use the „Remove point from

area edge‟ command to delete most of the additional points from the existing structural area

in that location, then drag the remaining blue grips into the correct position.

However, in this case, we want to separate the slab into areas either side of the wall in order

to create hinges, so create some further structural areas in these locations using the

„Rectangle‟ selection method from the right-click menu. Enter the default area loads from the

“Loads” tab Structural Area Default Loads section.



Figure 41: Structural areas above staircase



Command: Modify structural area

Select the edges of the slab areas that were just created that require hinges to the walls.

Adjust the properties of the slab edges between the wall areas and the roof (hinge in

direction of phix).

Figure 42: Hinges (kinematic constraints) at the intersection of roof and walls

6.3.2.11 Adjust beams in staircase for wind load transfer

The last step in modelling the building is an adjustment for the structural lines with the

dummy cross section in the staircase area. As described before (see also chapter 6.2 Define

materials and cross sections), the dummy beams have nearly no stiffness and serve only to

transfer loads to the slabs. However, in the staircase there is no slab to which the dummy

beams can transfer the loads so the program encounter problems while calculating.

Therefore, the beams in staircase area should be modelled with a realistic cross section and

stiffness.

Modify the display so that you can easily display and select the structural lines at the stair

location.




Define and assign a new cross section to beams in staircase area. Define a reinforced

concrete rectangular concrete cross section with the dimensions 200x200mm and assign to

the lines.

Figure 43: Beams in staircase area



6.3.2.12 Create named selection sets

This tool is used in conjunction with the Display Selection Set command. It can help you work

in larger 3D models as selections of elements are stored and easily recalled. This can help

save you time when selecting elements for viewing and modifying in larger systems.

Once a selection set is made, as described previously, further options will then appear in the

right-click menu under Named Selections. You have the option to „Save As New Selection‟.

You will be prompted to enter a name for the selection. Once this is confirmed, all named

selections will be listed in the Sys tab of the sidebar. You can also save selections under a

previously defined name.

To return all elements to the display, use the Named Selections command „Clear selection

(Display all)‟ or right-click on the Named Selections part of the Sys tab in the sidebar, and

then click Clear Selection.

Note that any new elements created will not be automatically assigned to a named selection

set, so you may need to periodically delete and recreate your named selections as your

model is developed.

Further information about named selection sets is given in the SOFiSTiK SOFinar titled

“SOFiPLUS 2010 Part 2: System Generation 3D - Concrete Structure with SE 17.03.2011”

which is available for download from the SOFiSTiK Infoportal.

In this tutorial, you can save the elements in each floor to a separate named selection set.

http://ftp.sofistik.de/pub/infoline/sofinare/english_sofiplus2010/SOFiPLUS_2010_Part2.zip



6.3.3 Additional loads (free loads)

So far only the superimposed dead loads and live loads have been applied to the slabs.

Wind loads, snow loads and loads onto the cladding still need to be defined.

6.3.3.1 Define actions

If not already defined, it is recommended to define actions for wind and snow loads now.

Command: Loadcase manager

Click on “Actions” tab and define the additional actions as shown in Figure 44.

Figure 44: Loadcase manager - Definition of actions



6.3.3.2 Define load cases for wind and snow

Before you create wind and snow loads, the corresponding loadcases should first be defined.

The individual loadcase number depends on your loadcase number scheme. (see also

chapter 4.1.2 Considerations about loads and actions).

Switch to the Loadcases tab and define loadcases for wind and snow as shown in Figure

45).

Figure 45: Defining new loadcases for wind and snow loads

Make sure that your new loadcases are defined with the correct action. These can be changed by left-clicking on the row to highlight it, then again at the position where the Action is defined (a dropdown menu appears).

6.3.3.3 Cladding loads

We assume that the cladding is supported from below at each storey, therefore the loads are

to be applied to each of the slabs except the roof does not get any cladding load.

Because the foundation is not considered in this example, the loads of the cladding at the

ground floor level do not have to be modelled.



Command: Loadcase Manager

Define a new loadcase number 3 with action G called “DL Cladding”.

Command: Display groups

Switch off all groups except group 49.

Command: Free line load

Define a load of 0.5 kN/m as load in gravity direction. Either enter the value in each box or

select „Uniform distribution‟. Right click on the drawing and select Polygonal mode. Enter the

load on all lines from 1st to 4th floors.

Figure 46: Load from cladding

In the dialogues of free loads you can select a reference type and a group-/ reference number. These are particularly useful if you want to define the loads at a distance away from the structure. These settings make sure that the loads are applied only to the correct structural elements.



6.3.3.4 Wind loads

Defining the wind loads is a bit more labour intensive. As you have read in chapter 4.1.2, the

wind loads are divided in different areas according to the design code. To make work a little

easier, we will define some new help layers in AutoCAD/ Sofiplus(-X); one for each wind load

case and one for the geometry. On these layers you can draw all lines/areas that you need to

define the wind loads which you can use to snap to when inputting the wind area loads.

Refer to the geometry in Figure 4 for these lines for both X and Y directions.

Drawing these help lines 0.5 m away from the real structure can help to keep an overview on the system. This might be useful, e.g. where you have a curved or multifaceted façade.

If you do place your loads away from the structure, you should set the depth on the LAR correspondingly (the distance away from the area at which loads are detected); in this tutorial, however, the lines will be drawn directly on the borderlines of the structure.

Figure 47: Help lines for wind load input in global x-direction (structure is not shown)



Command: Load distribution area

Create load distribution areas (LAR) to cover each entire side of your structure to the extent

of the border lines. The roof level doesn‟t require a LAR because a slab is present to transfer

any loads. The LAR could extend only over the areas where there are no walls, however in

this case we will defined LARs to transfer loads to the beams only.

The “affected group” should be set to group 49 once only. Leave the other two as “not

applicable”. The depth should be set, in this case, to 0.00 to avoid overlapping effects with

bordering walls.

Figure 48: LAR’s on all sides to simulate cladding

Command: Free area load

Into the dialogue, input the data for the load values and select reference type “LAR load

distribution area” and the number of your LAR you created one step before. Create an area

load for each wind load area (A-I) and each wind load case by snapping to the corner points

from the help layer geometry. Ue the example wind loading data given in chapter 4.1.2.

Take care with the sign of the loads according to the coordinate system. You will be able to

preview the load direction as they are created.

You can use Autocad commands/ options like _move, _copy, _mirror, _scale etc. to copy or modify free loads. You can simply change the direction of the wind load in the edit dialogue for the load area.



Figure 49: Input/modify wind loads

6.4 Export/ Checks

Now your input is complete. Please export your system and change back to the SSD. Now

you can proceed as usual with the linear analysis, the superpositioning, the design and the

post processing.

In case the export runs into trouble, you should check for error messages in URSULA as well

as in SOFiPLUS(-X) directly (press F2).

Check the system (mesh, supportings,…) and the loads (related to elements) with

ANIMATOR/ WinGRAF before starting the analysis. If the mesh has deformed elements

please try the recommendations given in chapter 4.3.2.

If you calculate the “Linear Analysis” in SSD, the program will return a warning message because of the “unstable” dummy beams in the system. It is just a hint, which does not require any changes. (dummy beams are unstable because they have a small stiffness)


Index of Figures 62

7 Index of Figures

Figure 1: Overview of the building ......................................................................................... 3

Figure 2: Building Floor Plan and Section 1-1 (not to scale) .................................................. 4

Figure 3: Wind Loading in Global Y Direction (shown in WinGraf as filled area and vector) ... 6

Figure 4: Overview of Wind Load Areas in Global X Direction (not to scale) .......................... 7

Figure 5: Overview of Load Areas for Wind in Global Y Direction (not to scale) ..................... 8

Figure 6: Overview of Vertical Connection Details ................................................................16

Figure 7: Overview of Horizontal Modelling Details ...............................................................17

Figure 8: Modelling Edge Columns Close to Slab Edges ......................................................18

Figure 9: Comparison of Wall Pillar Model Results ...............................................................19

Figure 10: System Information Dialogue ...............................................................................22

Figure 11: SSD Tasktree - Materials and Cross Sections .....................................................23

Figure 12: Ground Floor Plan with System Lines and Axes ..................................................25

Figure 13: Axis raster command dialogue ............................................................................25

Figure 14: X___AUFL Layer Containing System Lines .........................................................26

Figure 15: System with Structural Lines (WinGraf Plot) ........................................................27

Figure 16: creating cross section for dummy beams .............................................................28

Figure 17: Assign dummy beams to structure lines ..............................................................29

Figure 18: Loadcase Manager ..............................................................................................30

Figure 19: Creating a Structural Area ...................................................................................31

Figure 20: Loads on Slabs ....................................................................................................32

Figure 21: System with Structure Areas and Corresponding Loads ......................................33

Figure 22: Defining structural points for columns ..................................................................34

Figure 23: Generated mesh of first floor ...............................................................................35

Figure 24: Change system information .................................................................................36

Figure 25: Workspace with 3 viewports; numbers of viewports .............................................37

Figure 26: Original floor moved to first floor level ..................................................................39

Figure 27: First floor copied to all other levels ......................................................................40

Figure 28: Modify structural areas ........................................................................................41

Figure 29: Stretch view and selection box ............................................................................42

Figure 30: Ground floor elements with applied visual style ...................................................43

Figure 31: 1st floor and ground floor with dummy beams .....................................................44

Figure 32: Support conditions – structural lines ....................................................................45

Figure 33: Support conditions – structural points ..................................................................46

Figure 34: Beam hinges .......................................................................................................47

Figure 35: Quick graphical check of column hinges ..............................................................47


Index of Figures 63

Figure 36: Hinges (or kinematic constraints) at slab/wall intersections .................................48

Figure 37: Check system with ANIMATOR ...........................................................................49

Figure 38: 1st floor T-beams..................................................................................................50

Figure 39: Create new cross section for edge T-beams ........................................................50

Figure 40: System with T-beams ..........................................................................................51

Figure 41: Structural areas above staircase .........................................................................52

Figure 42: Hinges (kinematic constraints) at the intersection of roof and walls .....................53

Figure 43: Beams in staircase area ......................................................................................54

Figure 44: Loadcase manager - Definition of actions ............................................................56

Figure 45: Defining new loadcases for wind and snow loads ................................................57

Figure 46: Load from cladding ..............................................................................................58

Figure 47: Help lines for wind load input in global x-direction (structure is not shown) ..........59

Figure 48: LAR‟s on all sides to simulate cladding ................................................................60

Figure 49: Input/modify wind loads .......................................................................................61

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