Seismic Performance Evaluation And Seismic Design Of Hinged Wall With Brbs At Base

The main characteristics of building industrialization is standardization in structural design,precast manufacturing of components,mechanization of construction,and scientific management.However,several factors exist in current equivalent cast-in-situ manufacture which have restricted the development of building industrialization,such as different categories of beams and columns,complex joint connection and expensive lifting cost due to the heavy weight of precast components.To overcome the above factors,a separated load bearing system is proposed which is composed of Hinged Wall with BRBs at Base(HWBB)and hinged frame.HWBB is a resilient lateral force resisting system.In the hinged frame,the categories of beams and columns are reduced,which is good for developing standardization in precast manufacturing.Besides,high-strength concrete could be used for manufacture columns to reduce the weight of columns,resulting in a lower cost.What’s more,the beam to column joint is hinged and bears no moment resistance,making it easier for construction in site.The seismic capacity,seismic performance as well as the design method of HWBB are investigated through numerical analysis and a shake table test.Then a performancebased seismic design method is proposed for HTBB-hinged frame system.To provide the second seismic defense,gapped tendons are installed at two sides of HWBB.The seismic performance and seismic capacity of HWBB installed with gapped tenondons-hinged frame system are evaluated through test,numerical modelling as well as theoretical analysis.The main work and conclusions are summarized as follows:(1)The separated load bearing system which combines passive damping with precast manufacturing is proposed.Numerical methods are introduced in detail.Numerical investigations were performed utilizing nonlinear response history analyses to simulate the response of HWBB system to earthquake excitation.The displacement during both elastic and plastic states is controlled by the first mode,revealing that HWBB is able to effectively control the deformation mode of the whole structure.Besides,the peak roof displacements under three seismic levels(i.e.,Frequent Earthquake,Local Fortification Intensity Earthquake,and Rare Earthquake)fulfil the equal displacement principle.The moment demand of the hinged wall increased after BRBs yielded,indicating that higher mode effect must be considered.Moreover,the low-cycle fatigue property of a HWBB-hinged frame example is excellent to resist earthquakes due to small cumulative damage after consecutively excited to frequent earthquake,local fortification intensity earthquake and rare earthquake.(2)To evaluate the seismic performance and seismic capacity of HWBB-hinged frame structure,a distributed parameter model is developed for HWBB-hinged frame system.Frequency equation was derived and the displacement and forces equations have been derived based on the response spectrum method.The analyses results demonstrate that the displacement is controlled by the first mode,while the inner forces in the hinged wall is influenced by higher mode effects,revealing that higher mode effects must be considered in the strength design of the hinged wall.(3)A shake table test program on a 1:5 scaled HWBB system was presented and discussed.The objective of this study was to evaluate the seismic performance of the proposed HWBBhinged frame system.In general,the seismic test results confirmed the behavior and reliability of the HWBB system.In particular,the tests demonstrated the damage control capabilities of the HWBB system as the hinged wall remained in elastic and damage was concentrated in BRBs.BRB remained in elastic under Frequent Earthquake and yielded under Rare Earthquake.What’s more,the global hysteretic curve is stable and fat.The design objective was met.The deformation mode both in elastic and plastic states was controlled by the first mode,indicating HWBB is a high-ductile and resilient lateral force resisting system.The peak roof displacement under three seismic levels fulfils the equal displacement principle.Numerical modeling of the HWBB test model was developed and validated with shake table test results.Comparisons between numerical predictions and experimental results for the HWBB test specimen are presented.It revealed that the numerical model is able to capture the seismic response of the test specimen.(4)A seismic displacement-based design procedure for HWBB system was developed.The equal displacement principle is verified by a series of Single-Degree-of-Freedom system(SDOF)with elastic perfect plasticity hysteresis rule under different damping and ductile factors.It revealed that equal displacement principle is fulfilled when the period is larger than 0.7s.The rule of increase in the moment of hinged wall is described in detail.The seismic intensity superposition method is proposed to calculate the moment demand in the hinged wall.Design procedures of the seismic displacement-based design procedure is summarized in detail.Nonlinear time history analysis was conducted on two examples designed according to the design method to verify the effectiveness of the design procedure.It revealed that the design flowchart is simple and accurate,where elastic displacement spectrum is conveniently used for design.(5)To improve the anti-collapse capacity of HWBB,gapped tendons are installed in HWBB to provide the second seismic defense.To investigate the seismic capacity of HWBB installed with gapped tendons,a 1:5 scaled test specimen was conducted on a shake table test.It demonstrated that gapped tendons provided the third stiffness for the test model.Besides,the maximum strain in BRB is reduced,indicating that gapped tendons were able to protect BRBs.What’s more,the maximum inter-story displacement was reduced due to gapped tendons.Limit states of HWBB installed with gapped tendons-hinged frame were derived based on the Pushover curve.In addition,a parametric study was conducted to evaluate the effect of different parameters of the gapped tendons on the seismic performance of HWBB through IDA.The less the gap,the earlier that gapped tendons will work to provide the third stiffness for HWBB.The larger the area of the gapped tendon,the higher seismic capacity of HWBB will be achieved.