Modelo momento-rotação de ligações parafusadas entre viga e coluna em aço com dupla cantoneira de alma

Abstract

A predictor model of the non-linear moment-rotation relationship of semi-rigid connections steel beam-to-column with double web-angles is proposed by this study. This predictor model is based on a mathematical function of exponential format with two parameters in which the response variable expresses the value of the relative rotation beam-to-column from the predictor variable that corresponds to the bending moment acting on the connection, which is standardized by a dimensionless factor, defined in terms of three geometric design variables. Two data sets were formed from numerical analysis by the Finite Element Method of 162 connections. The adjustment parameters of the proposed model were obtained from the nonlinear regression of the data, using a mathematical optimization method (Simulated Annealing), in order to minimize the defined objective function. The values of the adjustment parameters of the model are given by equations in terms of the height of the pair of double webangles that form the connection, specifically for the surface roughness conditions represented by the slip coefficient 0.2 and 0.4. The proposed model is presented in a simple format and the value of rotational stiffness at any point of the moment-rotation curve can be obtained directly from its derivative. The moment-rotation curves predicted by the proposed exponential model present a satisfactory predictive capacity of the behavior of the connections, when compared to the data obtained by the numerical analysis. It was evidenced that the surface roughness conditions affect directly the behavior of the connections, so that the simulated connections with a slip coefficient 0.4 presented an increase of 21% in the initial stiffness value, when compared to the simulated ones with a slip coefficient 0.2.