design notes

Nr. inreg.: J/40/2760/2009

C.I.F.: 25215668

ING BANK NW Amsterdam - Bucuresti

Tel./fax: 031.428.61.06

E-mail: [email protected]

______________________________________________________________________________________________

Design Notes

eng. MIHNEA Horia-Ionut

eng. VASILESCU Adrian-Eugen

08-decembrie-2014

Nr. inreg.: J/40/2760/2009

C.I.F.: 25215668


Tel./fax: 031.428.61.06


______________________________________________________________________________________________

1. Design data: The building this document reffers to has the following characteristics:

- Height: 12m

- Ground floow area: 1150 sqm

- Number of stories: 3

- Altitude: 1260 m

The loads taken into account are according to SIA 260-2003, SIA 261-2003

1.1. Loads from snow

Characteristic snow loads on level terrain:

= [1 + (0

350)

2

] 0,4 2

0 = +200 as shown in annex D from SIA 261-2003

= [1 + (1200

350)

2] 0,4 2 but greater then 0,9 kN/m

2

= 5,10

2

Exposure coefficient:

= 1,0 for normal exposure

Thermal coefficient:

= 1,0

Form Coefficient:

Taking into account the building form we have two different coeficients:

Coefficient 1: Model of charge 1 for witch 1=0,8;

Coefficient 2: Model of charge 2 for witch 1=1,6;

Depending of the roof calculated we have 2 options for the characterisc loads from snow on the structure:

,1 = 0,8 1,0 1,0 5,1

2 = 4,08

2

,2 = 1,6 1,0 1,0 5,1

2 = 8,16

2

1.2. Live loads:

The loads from live loads in 5kN/m2

for category C3 of use. The concentrated load taken into account is 4 kN.

According to paragraph 9.4. from the code we need to study the dynamic properties for the slab. In the natural period of

vibration for walking is 2 Hz and for running is between 2,4 Hz and 3.5 Hz.

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1.3. Wind loads:

The global force on the building is calculated by:

=

Where:

cred is a reduction coefficient that takes into account the repartition of the forces on the surface of the building.

cd is the dynamic factor

cf is the dynamic factor

qp is the pressure

The characteristique value for wind is taken from annex E of SIA 261:

,0 = 1,1 /2

This corresponds for wind mediated at a couple of seconds interval at a height of 10m for a category III terrain.

The profile coefficient ch for categorie of terrain III for a height of the buildind of 15 m is about 1,1.

= .

The characteristic value for wind pressure: = ,0 = 1.1/2 1.1 = . /.

The reduction coefficient that takes into account the shape of the building is taken from the graph shown in figure 6 of

SIA 261. The worst case is when the wind is perpendicular on the faade.

=

=

50

14= 3.57

= .

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The dynamic coefficient takes into account the dymanic properties of the structure, the natural vibration period. According

to paragraph 6.3.5. for buildings with the maximum height of 15m it takes the value of 1.

= .

The pressure coefficient is taken from annex C of SIA 261:

h:b:d=14:50:25=0.28:1:0.5

In order to calculate the structure using global forces cf=0,95 for forces normal to the faade.

= = 0.76 1.00 0.95 1.21/2

= 0,87 /2

In order to calculate the elements for the faade the characteristic pressure taken into account will be 1,83kN/mp.

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1.4. Seismic loads:

The site placed in a zone characterized by a peak ground acceleration of 1,3 m/s2

(Zone Z3a).

The soil class taken into consideration is A (Hard rock or soft rock). For this soil type the following parameters are taken into

account: S=1,00; TB=0,15; TC=0,4; TD=2,00.

The damping ratio for a metallic structure is x=0,02.

The coefficient that corrects the spectrum is calculated with the following formula:

= 1

0,5 + 10= 1.19

With these site conditions the elastic response spectrum is as follows:

For 0TTB (1 +(2.51)

)

For TB TTC 2.5

For TC TTD 2.5

For TD T 2.5

2

For braced frames the ductility factor q=4.

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

Se(T)

Sd(T)

Td

TB

TC

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2. Calculation notes

In the design model the following combinations offer the significant dimensioning values:

1,35x(Dead Loads)+1,5x(Live Loads)+1,05x(Snow Loads)+ 1,05xWind



As the sesismic coefficient is so small the actions induced by the earthquake is lower than the other combinations.

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2.1. Dynamic properties:

Building modes:

Mode Period UX UY RZ

1 0.546 -0.604 35.272 -168.566

2 0.464 36.778 0.570 22.864

3 0.416 2.024 -6.326 -452.550

4 0.393 1.173 5.506 315.743

5 0.335 -0.270 -1.056 37.760

6 0.297 0.552 -0.234 2.142

7 0.292 2.785 0.801 5.287

8 0.269 -0.045 -0.461 3.835

9 0.253 2.746 1.127 -12.856

10 0.248 -3.030 0.040 -5.191

11 0.218 0.960 -0.100 3.051

12 0.214 0.557 -0.143 16.852

Modal Mass:

Mode Period UX UY SumUX SumUY RZ SumRZ

1 0.55 0.02 76.28 0.02 76.28 6.16 6.16

2 0.46 82.93 0.02 82.95 76.30 0.11 6.28

3 0.42 0.25 2.45 83.20 78.75 44.43 50.71

4 0.39 0.08 1.86 83.29 80.61 21.63 72.34

5 0.33 0.00 0.07 83.29 80.68 0.31 72.65

6 0.30 0.02 0.00 83.31 80.68 0.00 72.65

7 0.29 0.48 0.04 83.78 80.72 0.01 72.66

8 0.27 0.00 0.01 83.79 80.73 0.00 72.66

9 0.25 0.46 0.08 84.25 80.81 0.04 72.70

10 0.25 0.56 0.00 84.81 80.81 0.01 72.70

11 0.22 0.06 0.00 84.87 80.81 0.00 72.71

12 0.21 0.02 0.00 84.89 80.81 0.06 72.77

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2.2. Roof Beam

2.2.1. Type 1 - HEA 800 with initial horizontal prestress of 1500kN.

Beam characteristics

A: 286 cm2

Iy: 303400 cm4

h: 790 cm

Three tendons of 4 strands with a total area of 600 mm2

were considered. The steel used for the strands has a nominal

tensile strength of 1860 N/mm2

.

Moment from pretensioning (from loads on x axis)

M0 -742.5 0

M1 -742.5 5.375

M2 -742.5 10.75

M3 -742.5 16.125

M4 -742.5 21.5

Moments from loads

p= 89.87 kN/ml

M0 0 0

M1 3894.277 5.375

M2 5192.369 10.75

M3 3894.277 16.125

M4 0 21.5

0

2000

4000

6000

0 5.375 10.75 16.125 21.5

-800

-600

-400

-200

0

0.00 5.38 10.75 16.13 21.50

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Two hypothesis were considered:

1. The beam does not interact with the concrete slab;

2. The beam interacts with the concrete slab.

In both cases a sectional analysis software was used:

1. The beam does not interact with the concrete slab:

Nr. inreg.: J/40/2760/2009

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Tel./fax: 031.428.61.06


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Nr. inreg.: J/40/2760/2009

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2. The beam interacts with the concrete slab:

As seen for a dimensioning moment of 5192 the first hypothesis does not satisfy the necessary resistance as the capacity is

of 5036 kNm. The second one shows a capacity of 7691 kNm which is much more than needed. In conclusion some elements are

needed to make the two elements to work together.

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2.3. Column:

The worst case in from the gravitational loads:

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Nr. inreg.: J/40/2760/2009

C.I.F.: 25215668


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As shown before in the worst case the column is at 40% of capacity.

Nr. inreg.: J/40/2760/2009

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2.4. Secondary beams:

The secondary beams have a dimensioning moment of 77 kNm and a capacity of 205 kNm. The beams were dimensioned

from deflection. L/300=17mm. and the effective deflection is 17mm.

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2.1. Largest Console (HEA 450):

The secondary beams have a dimensioning moment of 540 kNm and a capacity of 895 kNm. The beams were dimensioned

from vibration. The limit taken into consideration is 5Hz for the slab.

Eng. Mihnea Horia-Ionut

design notes

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