![]() ![]() SAFE provides unmatched productivity to the engineer with its truly unique combination of power, comprehensive capabilities, and ease-of-use.SAPFire Analysis EngineĬSI solvers have been tried and tested by the industry for over 45 years. From framing layout to detail drawing production, SAFE integrates every aspect of the engineering design process in one easy and intuitive environment. However, use m11, m22, m12 = 0.70 (or 0.35) when considering the out-of-plane bending in wall.įlat Plates & Flat Slabs.0.25*Ig modeled as membrane – f11, f22, f12 = 0.25 / modeled as shell – f11, f22, f12, m11, m22, m12 = 0.SAFE is the ultimate tool for designing concrete floor and foundation systems. In this case, use a small modifier say 0.1 for m11, m22 and m12 so numerical instabilities could be avoided. Walls are generally not designed for out-of-plane bending to avoid excessive longitudinal reinforcement. Walls-Cracked.0.35*Ig similar to Walls-Uncracked (with modifiers of 0.35) Walls-Uncracked.0.70*Ig modeled as shell – f11, f22 = 0.70 If you apply the modifier to both f11 and f22 it hardly affects the results.įor slabs where bending is always in the out-of-plane direction, modifiers m11, m22 and m12 are required to model cracking behavior.Īssuming beams and columns are modeled as frame then the stiffness modifier table is as follows:īeams.0.35*Ig I22 = I33 = 0.35Ĭolumns.0.70*Ig I22 = I33 = 0.70 ![]() This means that the flexural modifier for EI should be applied to f22 for wall piers and to f11 for spandrels. When drawing in ETABS the default is to have the 1 axis horizontal and the 2 axis vertical. ![]() The above discussion applies assuming the local axes 1 and 2 of the shear wall area object are either vertical or horizontal. You should, however, note that some of our users use modifiers for f12 also, where they expect deterioration of shear stiffness and want to be realistic in their modeling. There is no recommendation about reducing the GA shear. The code recommendations in Section 10.10 of ACI 318 code are related to slenderness effects where flexural deformations govern so they have recommended modifying EI (corresponding to f11 or f22 for shear walls). In column and code terms f11 or f22 would correspond to modifications of EI or EA and f12 would correspond to modifications to GA shear. Refer to the below Figure which shows the direction of local axes and their corresponding stiffnesses:įor shear wall (both piers and spandrels), the flexural and axial behavior is modified by either f11 or f22 depending on the orientation of the local axis and the shear behavior is controlled by f12. inplane stiffness refers as f11, f22 and f12 and out-of-plane stiffness refers as m11, m22 and m12. In ETABS, shell or area element has two types of stiffnesses i.e. ![]()
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