Towards Lateral Performance of CBF with Unwanted Eccentric Connection: A Finite Element Modeling Approach

摘要

This paper presents a parametric investigation into lateral performance analysis of Concentrically Braced Frames (CBFs) having in-plane eccentricities at the connection of their braces. Nonlinear behavior analyses of a single bay, two-story steel frames with single diagonal concentric braces are taken as numerical examples. Static pushover analyses is carried out to show the impact of eccentricity values (5, 10, and 15 cm), location of the meeting point of brace and frame member axes, and the angle of brace with respect to beam axis. Finite element modeling of the whole members is conducted. Fine meshes are used in regions where inelastic deformations are expected. Numerical results show that in-plane eccentricities can be acceptable within a safe region (max. 10 cm for this specific case). However, no safe region exists for in-plane eccentricity in columns since the strength loss may be significant. Stiffeners are recommended in column web to reduce the strength loss. Their impact is less in strength loss but high in plastic strain developed in the critical region. Eccentricities have positive or negative effects on seismic behavior depending on the geometric properties of the frame, type of eccentricity and bracing configuration.