Cyclic modeling of cold-formed steel structures with sheathed shear panels

Abstract

The technology of cold-formed steel structures has been advanced and become one of the commonly used methods over time. However, the rate of application of the method has fallen short of the mark due to the designers have to deal with the different dimensioning principles and more failure mechanisms when the building constructed on a seismic region, such as in Turkey. Accordingly, in this study; design codes, specifications and manuals are investigated to form a general algorithm for the overall design of the shear wall as an assembly. Since the codes still need for experimental data; the previous major experimental researches are summarized. However, the tabulated design values of test results cannot be applied or extrapolated to wall assemblies in different configurations or construction details; it is tended towards to numerical methods instead of the experiments for the prediction of the lateral performance of the wall. Bouc-Wen-Baber-Noori (BWBN) model is selected for the simulation of the hysteretic behavior of the wall subjected to lateral in-plane load. It is assumed that the experimental force-displacement curve can be represented with a 4th degree polynomial. Then, the model is calibrated according to the experimental polynomial reasonably well. The model force-displacement backbone curves are interpreted with Equivalent Energy Elastic-Plastic (EEEP) method to obtain the design parameters such as, elastic limit, yield line, ductility, etc. The design limits are assigned to equivalent bracings with axial hinges which yields to similar results as the calibrated model for the single wall unit. Further, with some assumptions on the inter-story relations, nonlinear earthquake analysis of different wall configurations of multi-story structures is performed. It is observed that due to the insufficient test data provided about the selected experiment, experimental polynomial does not yield to the intended accuracy with the experiment itself. However, if more experimental studies with more data points are converted into BWBN model, the ranges for the parameters, each of which has different influence on the behavior, can be obtained for different wall configurations. Consequently, designers can perform FE analysis based on this introductory approach that needs for small number of elements to predict the lateral performance of the wall with minimized cost and time wasting of large-scale shear wall tests to be carried out for every new configuration where this construction technique is new to use such as Turkey.