Leaderboard

Mapped Spectral Accelerations Ss and S1 for 43 cities of Pakistan as per The Building codes of Pakistan 2021. Coordinates of cities have been marked on maps and respective accelerations values are tabulated. This task has been performed during the MSC structural Engineering course "Seismic Design of Structures" at UET Lahore, and was assigned by course instructor Prof.Dr.M.Burhan Sharif,CED UET Lahore. Mapped Spectral Acc.Engr.Sameer.UET.pdf

Why dont you simply assign insertion point to model this eccentricity? If you are having a frame, You can assign these insertion points to either the beam or the column a per situation? You can offset any end of member (Column or Beam) by this method to model eccentricity. If you are having a frame, and want to model the eccentricity at a specific joint, select the member at that joint (the member which is offest from center lines) and go to assign manu--> Assign insertion Point--> and assign desired offset nd desired axis. But dont forget to uncheck DON'T TRANSFORM STIFFNESS otherwise only geometry will be offset instead of stiffness i.e. required in calculations by the software. If you having only one column, You can also o the same, You want to provide eccentricity. You can either offset your load point as said by sir Rana, or you can offset your column centroidal axis by applying required offset in insertion points in desired axis. again dont forget to uncheck DON'T TRANSFORM STIFFNESS.

asad R is structural participation factor for the base shear.we make our structures in two different ways one that whole structure bears the base shear force and still remains in the elastic range there is no plastic hinge formation or non linear range... and other way is that we design our structure such that some part of base shear is resisted by structure and remaining part is shared by the ductility of the structure and structure goes into non linear range and hinges are formed. what we prefer that our structure behave the second way so it some part remains in the elastic range and other part in plastic.Plastic hinges are only preferred in the higher zones like you mentioned 3 or 4.In low zones we don't make plastic hinges as it makes structure uneconomical so we do more elastic and little bit ductile structure.. So the value of R is kept low as this value is divided by the base shear and the force which comes out is taken by the structure and remaining is taken by the ductile part of structure....In normal zones structures are low ductile and value of R is less. Now if we go to the higher zones like 3 or 4 what we want is that our structure should be flexible and it resist all the seismic forces and should not fail at any stage. So SMRF structure is preferred and Strong column weak beam structure is designed. So when we take value of R like 8 or 9 it means that base shear divided by R the value we get is resisted by structure and the remaining force is very big goes to the ductile part of the structure so just to get that much ductility or flexibility in the structure plastic hinge phenomena is introduced in the structure. What happens in the plastic hinge that our structure gets all the deformation and it goes to the plastic hinge region but it don't fail or fall down but this is only in very severe cases or very high zones. In plastic hinge we keep very close reinforcement at the beam column joint what happen with this reinforcement that concrete is more confined as we know that in concrete structures failure only occurs due to the cracking of concrete and steel fails at very very late stage so with this extra shear reinforcement we make structure flexible such that large deformations occur but no failure of structure. So i hope that you will get it now and Plastic hinges are made in SMRF structures as they are specially designed to resist severe seismic actions. and plastic hinges are formed that our structure should not fail at any cost it should go in non linear range ... I suggest you to read some thing about the push over analysis and non linear hinges in structures ... I hope that now you are much clear what i mean but still if you have any doubts please donot hesitate to ask...