Resumen

GAXIOLA CAMACHO, Oscar D. et al. Reduction of the response produced by damping and yielding in low-, mid-, and high-rise steel moment-resisting frames. Ing. sísm [online]. 2023, n.110, pp.86-108.  Epub 05-Feb-2024. ISSN 0185-092X.  https://doi.org/10.18867/ris.110.578.

The results of a numerical study to evaluate the response reduction produced by yielding of the material and viscous damping on Steel Moment Resisting Frames (SMRFs), modeled as complex multi-degree-of-freedom systems, are presented in this paper. Three SMRFs models representing the typical configuration of low-, mid-, and high-rise steel buildings are considered. It was found that the maximum reduction produced by yielding occurs for interstorey shears, followed by those of bending moments, interstorey displacements, roof displacements and axial loads. Elastic interstorey shears, for example, may be up to 300% larger than inelastic shears, however, for axial loads this amount ranges from 0% to about 70%, showing some limitations of the lateral static and modal analysis seismic methods where both, elastic interstorey shears and forces acting on members are reduced by the same numerical amount. The implication of the above statement is that the use of simplified methods may result in unconservative designs. The reductions produced by yielding are greater than those of damping for the case of interstorey shears and bending moments; however, such reductions are higher for damping for the case of axial loads. Hence, expressing the reductions of the response produced by yielding in terms of a fixed amount of viscous damping, as usually adopted in seismic codes, is not appropriate. This practice results in conservative design for interstorey shears and bending moments, but it may be very unconservative for the case of axial loads. A value of 5% can conservatively be used for interstorey shears and bending moments.

Palabras llave : steel buildings; steel moment resisting frames; viscous damping; yielding of structural material; multi-degree-of-freedom systems; global and local response parameters.