Presented By : Chirag Shah

Concrete floors in tall buildings often consist of a two-way floor system such as a flat slab, or a waffle system.

Advantages1. Optimum use of floor space2. Relatively simple construction process Disadvantages1. Generally flexible structure and lateral

deflection govern the design process.

The effective width of flat slab can be used to determine the equivalent width of slab.

The effective width depends on

1. Column aspect ratios2. Distance between

columns3. Thickness of flat

slab.

Cast in Place Concrete Building has inherent advantages of continuity at joints.

Beams framing directly into columns, can be considered rigid with the columns.

Beams carry shear and bending moments due to lateral loads often require additional construction depth.

The design and detailing of joints where beams and columns meet the special attention is required.

Advantages1. Rigid Frame systems for resisting lateral

and vertical loads have long been accepted as a standard means of designing buildings.

because they make use of the stiffness in the beams and columns that are required in any case to carry the gravity loads.

Limitation1. Rigid Frames are not Stiff as compared to

shear wall.2. Excessive depth of girder required to

make the rigid frame economical.

Disadvantages

When the Structure is of tube type and the adjacent distance between two columns are 40ft then the beam depth required is much more and this beam is called haunch beams.

If the depth of haunch beam is more then 3 ft then the posttensioning is used.

A haunch girder with more depth give the required stiffness for lateral loads without having to increase the floor to floor height.

This is achieved by making the mid section of the girder flush with the floor system.

The elevator shafts, stairwells necessary for access in a high rise must be protected by fire walls, as demanded by fire safety regulation.

It makes sense to exploit them in improving the building rigidity.

With their highly resistance to shear stress, are highly suitable for assuming the shear forces that arise through lateral loads.

Classification of Shear wall should be based on following criteria.

1. Based On Shape 2. Based on dimension3. Based on Opening

1. Rectangular2. Dumbled3. Intersection of Two Shear Walls

h/ l < 1 Square shear wall H / l > = 1 Slender Shear Wall

l

h

Solid With Opening Coupled Shear Walls

When two or more shear walls are interconnected by a system of beams or slabs, the total stiffness of the system exceeds the summation of the individual wall stiffnesses because, the connecting slab or beam restrains the individual cantilever action by forcing the system to work as composite unit.

used economically to resist lateral loads in building upto about 40 stories.

However planer shear walls are only efficient lateral carieers only in that planes hence it is necessary to provide wals in two orthogonal directions.

Most Popular System Broad Range of Application and has been

used for 10 – stories to as high as 50 stories or even taller building.

Using only shear walls to respond to lateral loads is impractival above about 500ft.

The lateral rigidity is gratly improved by using not only the shear wall system but also the rigid frame to resist lateral forces.

The total deflection of the interacting shear wall and rigid frame systems is obtained by superimposing the individual models of deformation as shown in fig.