Computational investigation on effective slab strip width of flat plate structures subjected to lateral load

Abstract

There are two distinct methods (Direct Design Method and Equivalent Frame Method) for the analysis of structures for vertical loads but there is a lack of well-guided code for plane frame ideal ization of a flat plate or slab with col umn line beam structure for lateral load analysis In 2D plane frame analysis, it is / required to take an appropriate width of the panel, which is structurally representative of the actual 3D frame. (The ratio of this slab strip width to the total panel width is known as effective slab strip ratioiln this work, an investigation is made to find the effects of various geometric parameters relating to flat plate structures, so that a definite guideline on determining the effective width of slab strip can be developecjl The investigation is also continued with structures having slab with column line beams to identify the influence of geometric parameters on effective slab strip ratio as well. . (To carry out the investigation, both 2D and 3D frames were modeled using finite element methodsTApplying the appropriate wind load on the 3D frame, lateral deflections are computed. Then applying the same wind load on the 2D frame and at the same time adjusting beam width the two deflections are matched as closely as possible. The ratio of reduced width by total panel width gives the value of effective strip ratio. The process is a simple trial and error method. The whole process is carried out under various parametric conditions. It has been found that some parameters like column size; slab thickness etc. has no effect on effective slab strip width for both types of floor. On the other hand, bay width and span length have found to have significant effect on effective strip width for both types of floor system. For structures with column line beams, the beam stiffness also has significant effect. Based on the results of the analysis, a chart for values of effective strip ratios as well as an equation are developed to explicitly determine the value of the slab strip width for flat plate structures. It has been shown with the help of a few examples that the suggested chart and equation are useful in structural analysis for predicting the width of effective slab strip with acceptable accuracy.