Non-linear simplified models for seismic response estimation of a novel tall timber-concrete hybrid structural system

Abstract

To better study the seismic performance of a novel high-rise timber-concrete (FaB) hybrid structural system, two non-linear simplified analytical models (i.e., Fixed Model and Controlled Model) are proposed in this paper. The timber-concrete FaB hybrid system mainly consists of a concrete frame-tube structure with large story height as the main structure, and several multi-story-high timber substructures on every concrete slab. The timber substructures are fixed to the main structure to form the Fixed Model (FM) or are connected by energy dissipation layers to form the Controlled Model (CM). To fully consider the different structural characteristics of the concrete main structure, timber substructures, and the connections in between, the FaB hybrid system is discretized and simulated with different non-linear parts in simplified models. For the concrete main structure, non-linear flexural springs and shear springs are adopted to simulate the flexural-shear behavior, while non-linear shear springs are used for simulating the timber substructures and energy dissipation layers. The model development procedure of the proposed simplified models is then presented in detail. Results from modal analysis, linear and non-linear time-history analyses of simplified models and refined finite element models of a 30-story timber-concrete FaB hybrid structure are compared and show good agreement. Specifically, the simplified models can satisfactorily predict the dynamic properties and seismic responses of the FaB hybrid system in linear and non-linear stages. The maximum difference between the simplified models and refined models varies from 2% to 20% for predicting the modal periods, floor displacement, acceleration, or base shear of the FaB system, which validates the accuracy of the simplified models. Moreover, by adopting the simplified models, the computation efficiency is also significantly enhanced, which is about 400 times faster than that of using the refined models. Outcomes of this study are expected to provide some references for future research and structure design for the novel timber-concrete hybrid system, which supports potential applications of such hybrid systems in tall buildings.