UNIT V BRICK MASONRY

EFFECTIVE HEIGHT OFWALL

Effective height of walls The effective height of a loadbearing wall is assessed by

allowing for the relative stiffness of the elements of structure (floors, roof, walls etc.) connected to the wall and the efficiency of the connections

hef=pnh Where: H is the clear storey height of the wall  pnis a reduction factor depending upon the edge

restraint or stiffening of the wall.nmay be 2, 3 or 4 depending upon the form of restraint (number of restrainededges)

Walls may be considered to be stiffened along a vertical edge if a suitable masonrystiffening wall or other stiffening element (e.g. r.c. column) is adequately connected along thatedge. Figures 5.2 and 5.3 illustrate the requirements for a masonry stiffening wall

The effect of vertical chases and/or recesses should be allowed for (see Section 6.4). A freeedge should be assumed if the thickness of the wall remaining is less than half the wall thickness

A free edge should also be assumed at the edge of any opening in the stiffened wall whichis greater than 0.25hin height or 0.25l in length or has an area greater than 10% of the area of the stiffened wall

EFFECTIVE HEIGHT OFCOLUMNS

Effective height The effective height,hef , of a wall,

panel or column should preferably be assessed by structural analysis. Alternatively, the values given in Table 12 may be adopted, wherehis the clear distance between lateralsupports

EFFECTIVE HEIGHT OFCOLUMNS

DESIGN LOADS

All elements of a raised floor system must be properly sized to support the design loads

Continuous Load Path A continuous load path must be provided to transfer all lateral

and vertical loads from the roof, wall, and floor systems to the foundation.

A load path can be thought of as a "chain" running through the building.

Because all applied loads must be transferred to the foundation, the load path chain must connect to the foundation.

To be effective, each "link" in the chain must be strong enough to transfer loads without breaking. A continuous load path is especially important in areas subject to high winds and/or seismic forces

WIND AND SEISMIC CONSIDERATIONS Construction in areas subject to high-wind and

earthquake forces can pose unique problems to the designer and builder.

Where wind speeds are less than 110 miles per hour, construction should be in accordance with the International Residential Code. In regions where wind speeds equal or exceed 110 miles per hour, raised floor systems should be designed and constructed in accordance with the WFCM.

LOAD DISPERSION

The angle of dispersion of vertical load on walls shall be taken as not more than 30” from the vertical.

some criticism, it is permitted by the code in the absence of more reliable information.

As an alternative of using an increased permissible stress value when checking safety of structural components, one can use a 25% reduced load for load combinations involving wind or earthquake

forces and compare with full permissible stress values.

, the modified load combinations b, c and d will be:

b) 0.75 [DL + IL + (WL or EL)] c) 0.75 [DL + WL] d) 0.75 [0.9DL +EL

PERMISSIBLESTRESSES

permissible stress is considering for design of structural items. if the stresses developed in a structure due to service loads do not exceed the elastic limit.This limit is usually determined by ensuring that stresses remain within the limits through the use of factors of safety. factor of safety =allowablestress/permissiblestress.   

CLASSIFICATION OF WALLS

Load Bearing Walls  These walls take the load of super structure and

transmit it to the ground through foundation.   These can also serve the purpose of dividing the space

into required rooms etc. These are also accommodating door and windows

where required.  These are of 9” or more thickness. Such walls are made in first class bricks and rich

mortar.

LOAD BEARING WALLS

NON LOAD BEARING WALLS

These walls serve the purpose of dividing the space into required rooms etc.

These are also accommodating door and windows where required.  

 These can be made into thin sections to save the space. Non load bearing walls are only partition having no load

of super structure so these can be easily changed whenever required to change the space of the room. 

These walls are made 3 inches, 4.5 inches and 9 inches thick as per the requirement of the site.

NON LOAD BEARING WALLS

SUPER STRUCTURE: Brick work from DPC level to the roof level/slab level. If columns provided in drawings then RCC columns to

be laid. Rain water pipe is to be embedded in walls. Fixing doors, windows and ventilators frames in walls. RCC (Reinforced Beam & slab for roof) including M S

Steel bars according to the designs. Tile terracing lay with brick tiles on the top of the roof

slab. Fixing doors and windows shutters. Fixing cupboard in the rooms and Kitchen etc. Fixing iron grills for safety of the house. Providing cement plaster on ceiling and walls. Laying floors including base coat.

STABILITY The stability of a wall may be affected by foundation

movement, eccentric loads, lateral forces (wind) and expansion due to temperature and moisture changes

Eccentric loads, that is those not acting on the centre of the thickness of the wall, such as from floors and roofs, and lateral forces, such as wind, tend to deform and overturn walls. The greater the eccentricity of the loads and the greater the lateral forces, the greater the tendency of a wall to deform, bow out of the vertical and lose stability. To prevent loss of stability, due to deformation under loads, building regulations and structural design calculations set limits to the height or thickness ratios (slenderness ratios) to provide reasonable stiffness against loss of stability due to deformation under load.

To provide stiffness against deformation under load, lateral, that is horizontal, restraint is provided by walls and roofs tied to the wall for stiffening up the height of the wall and by intersecting walls and piers that are bonded or tied to the wall as stiffening against deformation along the length of walls.

Irregular profile walls have greater stiffness against deformation than straight walls because of the buttressing effect of the angle of the zigzag, chevron, offset or serpentine profile of the walls, illustrated in Fig. 44. The more pronounced the chevron, zigzag, offset or serpentine of the wall, the stiffer it will be

CLASSIFICATION OF WALLS

Rubble walling and random rubble - wall. Dowels. Cramps - Walls - Stones. Weathering to cornices, Cement joggle - Stones - Walls Cornice an parapet walls, Saddle joint - Walls - Stones. Openings to stone walls - Lintels. Stone Masonry Walls. Vapour barrier: Vapour

check, External insulation, Resistance to the passage of sound.

Solid walls: Mechanical fixing, Internal finish. Solid walls: Adhesive fixing. Solid walls: Thermal insulation. Internal insulation. Brick lintels - walls. Boot lintels - Walls.

Prestressed concrete lintels and Composite and non-composite lintels- Walls.

Reinforcing rods and Casting lintels - Walls. Head of openings in solid walls and Timber lintel

s. Bonding of bricks at rebated jambs - Walls. Jambs of openings and Rebated jambs - Walls. Openings in solid walls. Slate and tile hanging - Walls. External weathering to walls of brick and block a

nd Rendering. Resistance to weather - solid wall of brick. Solid Walls. Cavity wall insulation: Partial fill, Insulation Mate

rials, Insulation thickness, Total fill, Thermal bridge.

Resistance to the passage of heat – Walls. Concrete lintels Walls.