Numerical simulation of the coupled tension-shear response of an innovative dissipative connection for CLT buildings

This work presents a numerical macro-element model able to simulate the dynamic response of an innovative ductile and highly dissipative bracket for assembling of cross-laminated timber structures. This bracket resists to both tensile and shear forces and has been conceived to realize all the seismic-resistant joints of the building with a unique type of connection able to maximize the seismic capacity of the entire structure. The main issue of these kinds of connection is the reliability of numerical models in reproducing the coupled tension-shear behaviour and dissipative capacity with reduced computational effort, so as to simulate the non-linear response of complex buildings. With this aim, a numerical macro-element model was developed within the finite-element framework OpenSees using an assembly of linear beams and plastic hinges capable of simulating the complete tension-shear strength domain of the connection. The macro-element model was calibrated referring to the results from quasi-static cyclic-loading tests of the connector performed in pure shear and pure tension. The coupled tension-shear behaviour of the macro-element model was then validated on the results from independent numerical simulations performed using detailed 3D models with solid finite elements, including material and geometric non-linearity. Obtained results demonstrate that the developed macro-element model is able to describe accurately the hysteretic behaviour of the bracket with a very low computational effort. Therefore, it can be conveniently adopted to simulate the seismic response of complex structures.