Pinned and Fixed Connections in "2 Storey X-Braced" Frames

The main objective of the present paper is to point out the influence of fixed and pinned connections, for diagonals and beams, on the seismic behaviour of concentrically braced frames. Three constructive configurations were considered for two concentrically "2 storey X-braced" frames with six and ten storey, having two spans of 6.0 m and a storey height of 3.5 m. In the first constructive configuration, fixed connections were used for all kind of structural elements. In the second configuration, pinned connections were considered at the ends of the diagonals and fixed connections were used for the beams. In the third configuration, pinned connections were considered for both diagonals and beams. Each distinct constructive configuration was subjected to dynamic nonlinear analyses using Vrancea acceleration records, calibrated to a peak ground acceleration value of about 0.3 times the acceleration of gravity. The behaviour of the different frame configurations during these analyses was compared (the extreme values for base shear forces and horizontal floor displacements, the amount of dissipated energy, the maximum inelastic deformations and member forces recorded during the analyses). The steel consumption was estimated for all analysed constructive variants.