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Thankyou

You may find the following topic of interest too: http://www.sepakistan.com/topic/1545-what-would-be-the-proper-choice-between-shell-and-frame-for-modelling-12m-x-06m-vertical-element/?p=3577 Thanks.

There are different ways in which your question can be answered. I will try to explain how existing code provisions team up to satisfy statement posted above or how the analysis steps taken by a Structural Engineer work to meet the 21.1.1 Clause. Here is the response in-terms of code clauses enforcing integrity: 1) The seismic-load-resisting system must have sufficient strength to limit ductility demand. R implies level of accepted ductility but code also imposes maximum period to be used for strength check T< CuTa. The reason: Over-estimate of period results in lower required strength. This indirectly puts a requirement for minimum strength. So code is enforcing minimum strength. 2) Similarly, the seismic-load-resisting system must have sufficient stiffness to control drift. Drift control indirectly puts a requirement for minimum stiffness. Code wants you to have minimum stiffness. 3) Critical elements are required to be designed for amplified load. (Use of Omega for collectors, elements supporting discontinuous frames etc. See AISC 341 for more detail). This is damage control. 4) The seismic-load-resisting system must have sufficient integrity to prevent separation of elements and components. This is satisfied by ensuring deformation compatibility and designing all elements for tie/ anchorage forces. 5) Stability is satisfied by requiring the seismic-load-resisting system to have sufficient strength and stiffness to ensure that second order effects are not significant. Second order check is performed. See equation below. This ensures that even under large seismic displacements, we have sufficient ability to resist seismic load. When doing your structural analysis to code/ ASCE 7, you are indirectly striving to achieve integrity that would satisfy much higher forces than what you have designed for. The above points just provide summary of some of the checks built in the code to ensure that. Thanks.

Some general concepts, regarding shear reinforcement output of ETABS, are discussed in following thread: http://www.sepakistan.com/topic/1584-shear-reinforcement-in-etabs/ In your case for IS 456-2000 code, the shear reinforcement value should be in 'mm2/m' units. You may verify this manually, using critical shear force values of relevant members (beam or columns) output by ETABS. To provide required shear reinforcement, select a suitable rebar size (e.g., 10 or 12 mm diameter) and calculate required bar spacing as per normal procedure per IS 456. Shear reinforcement may be higher for a cantilever beam (compared to a beam supported at both ends), as all the shear force of a cantilever beam is transferred to a single support (instead of of two supports as for a beam supported on two supports). You may check & verify this from the shear force diagrams of the two beams. HTH

W salam, These concepts need some fundamental theory of development of seismic analysis procedures (static procedures) in codes as briefed below, When engineers decided to go for an earth quake resistant design,then they initially proposed to assign a horizontal load of "0.1 x Weight of structure" to cater for seismic forces.With the passage of time several geo-technical and site specific response characteristics were included in analysis for evaluation of seismic forces and structural members were designed to resist these forces in their elastic range i.e to not yield under these forces. Structures designed accordingly surprised engineers, as they were observed to show little tolerable non structural damages in seismic events considerably greater then those considered in evaluation of seismic forces.This leads to the development of concept of energy dissipation and over strength factor i.e under cyclic seismic loading structures have the ability of resistance beyond the elastic range of stresses in members (after yield), in proportion to their ductility.Since then started consideration of this structural over strength characteristics that consists in reduction of design seismic forces in accordance with their energy dissipation characteristics or mathematically reduction of base shear by division with over strength factor. For ex in accordance with UBC97, if on a structure the actual seismic force i.e Cv.I/W=550 & over strength or ductility factor is R=5.5 then Seismic shear will be 550/5.5 = 100, then structural members will be designed to remain elastic or not yield under the lateral force of 100, whereas they will dissipate the remaining 450 in inelastic range or in terms of energy it can be said that this structure is able to dissipate 450/550x100 = 81% seismic forces through its ductility and is required to design elastic only for 19% of actual seismic forces. In the lights of above these clauses could be defined as follows, ") 21.1.1 says, ........................................For which, design forces , related to earth quack forces, have been determined on the bases of ENERGY DISSIPATION IN NONLINEAR RANGE OF RESPONSE". For every structure,seismic forces are evaluated in accordance with corresponding over strength factor that indicates the extent of probable energy dissipation. 2) Commentary of R 21.1.1 says, The integrity of the structure in the inelastic range of response should be maintained because the design earth quack forces, defined in documents such as ASCE/SEI 7, the IBC, the UBC and NEHRP provisions are considered less than those corresponding to linear response at the anticipated earthquack intensity. As defined above, structures are designed for seismic forces that are reduced by over strength factor however actual fores are times greater than that, therefore code requires that when structure is subjected to actual seismic forces(plastic state),then although structural damages in members are tolerable but integrity of structural members should necessarily be maintained so that structure will not collapse.This condition is another form of philosophy of safety in code under seismic events that says "Under major earth quake,structure should be designed to have structural & non structural damages but should not collapse".