In order to achieve better mechanical performance and construction efficiency, the outrigger bracket with a "through type" interior diaphragm (OBTID) connection is proposed for application in semi-rigidly connected composite structures. The mechanical behaviour of OBTID connections in two frame tests under lateral cyclic loads is investigated to reveal the failure mechanism. Based on the test observations, a component-based model is proposed to analyse the nonlinear behaviour of semi-rigid connections by decomposing the connection components and putting forward the constitutive law of each component. Furthermore, the proposed model is implemented in a general commercial finite element package and a program for nonlinear analysis of semi rigidly connected composite structures is developed by combining the component-based model with the previous fiber beam-column model. Then, a comparison between the numerical results and experimental results in both connection level and frame level indicates that the proposed component-based model can predict the complex nonlinear behaviour of semi-rigid connections with good accuracy. Additionally, the contribution of bolt slip to connection rotation is analysed to clarify the pinching effect, and the semi-rigidity of OBTID connections are compared with provisions of Eurocode 3 and that of other similar semi-rigid connections.
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