Seismic Performance Evaluation Of Infilled Rocking Wall Frame Structure

Reinforced concrete frames are prone to soft-story mechanism during earthquakes,where column hinges form prior to beam hinges.With limited energy dissipation ability and large residual deformation,it is not beneficial to fast resilience after earthquakes.This research proposes a novel infilled rocking wall frame system,which aims at controlling deformation mode in the frame and avoiding soft-story mechanism.A rocking wall with relative large stiffness will force the frame deforms uniformly along the height,which makes full use of steel and concrete.The base of rocking wall is separated from the foundation,reducing strength demand of the wall and foundation,and enlarging deformation ability of the wall.In the system,rocking walls are arranged inside the frame,which is space-saving and construction-friendly.The research investigates seismic behavior of infilled rocking wall frame from three aspects,static performance,dynamic performance and economic performance,through physical testing,theoretical derivation and numerical simulation.The layout of this research and its main contributions proceed as follows:(1)An infilled rocking wall frame model with a scaling factor of 1:2 is designed and constructed.Seismic behavior of infilled rocking wall frame is investigated through pseudo-static testing by comparison with reinforced concrete frame.Capacity is effectively enhanced and deformation mode is controlled by rocking wall.Residual drift of infilled rocking wall model is almost zero after cyclic loading up to structure drift ration of 1/50.Soft-story mechanism is successfully converted to overall yielding mechanism.Capacity of retrofitted model is further improved by wrapping steel plates and installing dampers.Deformation ability of beam-column joint is improved.The base shear does not degrade at structure drift ratio of 1/50 with unobvious damage.The base shear degrades at structure drift ratio of 1/30.(2)A distributed parameter model is proposed for pin-supported wall frame.Displacement and force distribution is solved under three kinds of external load by compatibility and equilibrium.Accuracy of the theoretical derivation is verified by finite element model.Based on the distributed parameter model,influence of wall rocking on force distribution is further discussed in the infilled rocking wall frame.(3)Design method of infilled rocking wall frame is proposed.Application scope,design principal,procedure and construction measure is given.The design method is implemented on an 8-story structure.Design force and reinforcement is compared with reinforced concrete frame.(4)Static performance,dynamic performance and economic performance of infilled rocking wall frame are assessed by static pushover analysis,time history analysis and financial loss analysis.Uniform deformation and frame shear force distribution is demonstrated in infilled rocking wall frame under both static and dynamic loads.According to capacity spectrum method and incremental dynamic analysis,infilled rocking wall frame is certified to resist earthquake of higher intensity than reinforced concrete frame under identical design conditions.Deformation response and dispersion is minimized.Repair cost in infilled rocking wall frame model is slightly larger than reinforced concrete frame under small earthquakes,and about 62% and 80% of the corresponding cost under medium and large earthquakes.The expected annual repair cost in infilled rocking wall frame model is 72% of that in reinforced concrete frame model.