On the behaviour of mid-connection in off-centre bracing system

This paper presents theoretical and experimental investigations on the behaviour of mid-connections in an off-centre bracing system. This braced system is preferred by architects because of the eccentricity introduced by the diagonal brace members, which allows a wider area of opening in the frame panel. Assumptions when designing the system in two dimensions has led to severe damage of structures based on observations of the recent Bam earthquake. In this regard, the assumption of mid-connection of the brace elements has a significant effect on the behaviour, stability and lateral buckling load resistance of the system. In order to investigate the effect of mid-connection types on the behaviour of the system, two possible implementations of this connection were considered. Based on the slope-deflection method and equilibrium equation at the connection point, the stiffness matrix was obtained to calculate the lateral buckling load of the system. In addition, to validate the theoretical calculation and practical consideration of the system, two frames of one-third scale were fabricated and tested. A good agreement between the experimental results and the theoretical calculations was obtained