A wide open bottom story of a frame building is often expected by owners for use as a garage or shops.However,this leads to weak stories due to abrupt changes in lateral stiffness and often results in unexpected story...A wide open bottom story of a frame building is often expected by owners for use as a garage or shops.However,this leads to weak stories due to abrupt changes in lateral stiffness and often results in unexpected story collapse as observed in many previous earthquakes.To retrofit frame buildings that have experienced weak story damage,a tendon system is proposed in this study,which consists of a set of swaying columns and tendons.The swaying columns are used to uniformly redistribute the lateral deformation along the height,while the tendons provide extra lateral stiffness and renders the entire structural system a re-centering capability.To avoid unnecessary forces to swaying columns,pin-connections are used at the bottom.Tendons are placed over the entire story to gain large elastic displacements.Parametric analysis reveals that the swaying column,with a stiffness of about 0.9 times that of the weak story,and the tendons attached at the roof,with a stiffness of 0.04 times that of the weak story,can provide the optimal performance with a maximum residual story drift angle of less than 0.5%.Online hybrid tests were carried out,which demonstrated that uniformly distributed story drifts and acceptable residual deformation could be achieved by the proposed tendon system.展开更多
The most critical drawback in currently used steel reinforcement in reinforced concrete(RC)structures is susceptibility to accumulation of plastic deformation under excessive loads.Many concrete structures due to dama...The most critical drawback in currently used steel reinforcement in reinforced concrete(RC)structures is susceptibility to accumulation of plastic deformation under excessive loads.Many concrete structures due to damaged(yielded)steel reinforcement have undergone costly repairs and replacements.This research presents a new type of shape memory alloy(SMA)-based composite reinforcement with ability to withstand high elongation while exhibiting pseudoelastic behavior.In this study,small diameter SMA wires are embedded in thermoset resin matrix with or without additional glass fibers to develop composite reinforcement.Manufacturing technique of new proposed composite is validated using microscopy images.The proposed SMA-FRP composite square rebars are first fabricated and then embedded in small scale concrete T-beam.3-point bending test is conducted on manufactured RC beam using a cyclic displacement controlled regime until failure.It is found that the SMA-FRP composite reinforcement is able to enhance the performance of concrete member by providing re-centering and crack closing capability.展开更多
基金National Science Foundation for Distinguished Young Scholars under Grant No.52125806the Heilongjiang Touyan Innovation Team Program under Grant No.3016。
文摘A wide open bottom story of a frame building is often expected by owners for use as a garage or shops.However,this leads to weak stories due to abrupt changes in lateral stiffness and often results in unexpected story collapse as observed in many previous earthquakes.To retrofit frame buildings that have experienced weak story damage,a tendon system is proposed in this study,which consists of a set of swaying columns and tendons.The swaying columns are used to uniformly redistribute the lateral deformation along the height,while the tendons provide extra lateral stiffness and renders the entire structural system a re-centering capability.To avoid unnecessary forces to swaying columns,pin-connections are used at the bottom.Tendons are placed over the entire story to gain large elastic displacements.Parametric analysis reveals that the swaying column,with a stiffness of about 0.9 times that of the weak story,and the tendons attached at the roof,with a stiffness of 0.04 times that of the weak story,can provide the optimal performance with a maximum residual story drift angle of less than 0.5%.Online hybrid tests were carried out,which demonstrated that uniformly distributed story drifts and acceptable residual deformation could be achieved by the proposed tendon system.
文摘The most critical drawback in currently used steel reinforcement in reinforced concrete(RC)structures is susceptibility to accumulation of plastic deformation under excessive loads.Many concrete structures due to damaged(yielded)steel reinforcement have undergone costly repairs and replacements.This research presents a new type of shape memory alloy(SMA)-based composite reinforcement with ability to withstand high elongation while exhibiting pseudoelastic behavior.In this study,small diameter SMA wires are embedded in thermoset resin matrix with or without additional glass fibers to develop composite reinforcement.Manufacturing technique of new proposed composite is validated using microscopy images.The proposed SMA-FRP composite square rebars are first fabricated and then embedded in small scale concrete T-beam.3-point bending test is conducted on manufactured RC beam using a cyclic displacement controlled regime until failure.It is found that the SMA-FRP composite reinforcement is able to enhance the performance of concrete member by providing re-centering and crack closing capability.
