Study on Elastic-Plastic Design Method for Piping Supports With Outer Diagonal Brace Considering Variation of Material Properties

Abstract The design method considering elastic-plastic behavior of piping supports with a diagonal brace has not been studied because buckling may precede elastic-plastic behavior. Therefore, the stability of the response of the piping system including the elastic-plastic piping supports with outer diagonal brace was confirmed, and then, the elastic-plastic analysis evaluation method of the piping system including the piping support with an outer diagonal brace subjected to an earthquake excitation was studied. Yield stresses of actual piping supports are variable and reported to be often in the 1.0 to 1.5Sy range, where Sy is the design yield stress. Therefore, in order to confirm the effect of the variation of yield stress and second inclination of the bi-linear strain stress curve on the response of the piping system, seismic response analysis of the piping system was conducted using yield stress and second inclination as parameters. A shell model which was confirmed to be capable of simulating test results in a previous study was used for modeling piping supports with an outer diagonal brace, and the direct integration method was used for seismic response analysis of piping systems. As a result, the effect of the variation in yield stress of the elastic-plastic support on the response was confirmed. The design safety factor corresponding to the uncertainty of yield stress which is indispensable for the design method of elastic-plastic support was proposed.