Dynamic behavior of multifunction structural panels for multi-hazard mitigation

Abstract

<p>In this study, a novel multifunctional panel that can resist structural loads, control room temperature and dissipate vibration energy due to wind or seismic hazard is proposed. All these functions are enabled by a liquid-filled multi-capillary structure inside the panel. The free-flowing liquid in the capillaries can provide thermal exchange from external sources and liquid head loss generation when it flows through internal orifices. Two types of multifunctional panels, including a pultruded glass fiber-reinforced polymer (GFRP) panel and a reinforced concrete panel, are manufactured to assess their damping performances. Shake table tests on the GFRP multifunctional panel show that it has high resistance to ground accelerations but relatively low energy dissipation capability. Filled-in water can greatly reduce the GFRP panel’s vibration through liquid damping, with reduction effect increasing with the water amount. Dynamic tests of reinforced concrete multifunctional panel also proved that the oscillating liquid inside can enhance the total damping of the structure. The liquid motion in the multi-capillary system can be described as a tuned liquid multiple columns damper (TLMCD) model, a nonlinear dynamic model that simulates the liquid surface movement in each capillary. The friction damping and head loss damping due to the internal orifices are identified as the sources of energy dissipation in this system. Numerical solutions of the dynamic model are validated through both computational fluid dynamic (CFD) simulation and a series of dynamic tests of the manufactured reinforced concrete multifunctional panel. The nonlinear dynamic model is further linearized using energy equivalent method. Optimum parameters of a TLMCD attached to various primary systems can be obtained from the linearized model, and transfer functions indicate that optimized TLMCDs have better damping performance than single or multiple tuned liquid column dampers (TLCDs) when mitigating multiple-degree-of-freedom (MDOF) primary structures. Semi-active TLMCDs with controllable valves are proposed as well. Sliding mode control method is employed to calculate the control forces in a TLMCD. Study of a benchmark building equipped with a semi-active TLMCD under stochastic wind hazards show significant damping improvement from the passive TLMCDs.</p>