Leaderboard

There is a rule of thumb that the Structural Engineers of 70's used and still used as a means of getting an idea about how steel may require. It is expressed as (story/3+7) psf.

not true in all cases. uncontrolled internal temperature has the same effects like outside sun heat on the structure. There are usually documents stating weather station data. You should use mean yearly average highs and lows not daily. It also depends on approval authority. For example in Dubai, limit is 45m. Expansion joints are nice from structural point of view only. As a structural engineer, Id try my best to avoid them. Construction isnt that easy for expansion joints. What about water leakage? Except ground floor columns and walls that will have huge forces due to restrain (supports). This is my opinion. I don't think T+E should be added.

@ZOHAIB SATTAR NAGRABefore replying to your question, I would like to clarify that I don’t know the plane of your building, you have big opening whose nature and geometry is unknown to me. Expansion joint might play an important role in your building, if there is abrupt change in the plan, I would recommend to provide expansion joint. In connection to your question, keeping in view the conditions of frame end conditions and heating of the building, briefly, I would like to explain as follows: 1. Intermediate floors will not be exposed to weather conditions; they will be much cooler than roof. Ask yourself what will happen if you will put this load on intermediate floors? Axial tensile or compressive stresses will be developed in your structure. SOLUTION: There will be no loading on intermediate floors at that time, except workers or temporarily loading, the reinforcement you already provided would be sufficient enough to cater theses build up stresses. Nothing will happen to your structure. 2. Your structure will act together, slab will not behave alone; in fact these volumetric changes will occur about Centre of Stiffness. Your frame will try to contract or expand as whole. Connection are not ideal rigid connection, the structure will have some relief from theses axial stress through joints, shrinkage/temperature steel and also through micro cracking which will not be visible.

@SALMAN CH my building is 227 ft x 170 ft with 60 ft x 60 ft opening in centre.as per ACI report 224.3 if diifference of annual mean temperature and maximum low or high temp (which ever is high ) is less than 20 C then we will give expension joint after 90m.but if it is greater than 60m then we will provide it after 60m. plz check image attached. plz explain third point I have a model file in office in which they have applied 27 degree only on roof .Why they have not applied it on buildiing exterior sides expose to climate like expterior columns and exterior beams and exterior walls on each story.? how to overcome the (axial load on beams) problem which you have explained in third point.? do we have to play with stiffness modifires? procedure?

yepp agreed with @Ayesha its depends on your layout and architectural work, but the best way to do it is place the shear wall on the place closest to centre of mass this already proved by some journals on internet as a kind of optimum place to put the shear wall on, but the internal forces of shear wall would have a bigger result cause it tends to withstand more mass you should try several numbers of model to pick which one the best in reducing structural displacement and withstand internal forces.

This is a very good question. An optimal location of shear walls in a high rise building depends on its architectural features that dictate the mass distribution of the structure as well as the lateral force resisting system of the structure. As a structural engineer, you will have to try different locations considering that optimal location will be one that shall result in centre of rigidity of structure being closet to centre of mass. This is the general principle.