Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely u...Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.展开更多
Severe damage to steel space structures is rarely reported when compared to other structural systems damaged during past major earthquakes around the world. Two gymnasiums of steel space structures in downtown Lushan ...Severe damage to steel space structures is rarely reported when compared to other structural systems damaged during past major earthquakes around the world. Two gymnasiums of steel space structures in downtown Lushan County that were damaged during the 2013 M7.0 Lushan earthquake in China were investigated and the observations are summarized in this paper. Typical damage to these two steel space structures ranges from moderate to severe. Moderate damage includes global buckling and dislocation of bolted connections of truss members, and inelastic elongation of anchor bolts and sliding of pedestal plates of supports. Severe damage includes member fracture caused by local buckling, and fracture failure of anchor bolts and welds. The distribution of structural damage to these two structures is described in detail and future research opportunities are suggested.展开更多
The seismic behavior of a school gymnasium, whose steel grid roof was heavily damaged during the Mw6.6 Lushan earthquake in 2013, is simulated through nonlinear dynamic analysis. The simulated damage is compared with ...The seismic behavior of a school gymnasium, whose steel grid roof was heavily damaged during the Mw6.6 Lushan earthquake in 2013, is simulated through nonlinear dynamic analysis. The simulated damage is compared with field observations to validate the numerical model, based on which a parametric study was performed to provide insight into the failure process and damage patterns of steel grids. The results suggest that the grid damage is strongly related to roofsubstructure interactions. These include not only the substructure's amplification of the vibration, but the uncoordinated displacement of the substructure's columns which support the grid also play an equally important role. In particular, the latter effect may significantly alter the internal force distribution in the steel grid and lead to unexpected buckling of members that are proportioned as tension-only members. While such interactions are generally not accounted for in the design practice for grid structures in China, similar seismic damage may be expected for other existing grid roofs in future earthquakes. As is also demonstrated in this study, seismic isolation of the roof is a promising solution to protect grid roof structures by mitigating the detrimental effects of roof-substructure interactions.展开更多
The damage to the masonry-infilled reinforced concrete( RC) frame buildings in Charikot,the capital city of Dolakha district in Nepal,during the 2015 April-to-May Nepal earthquake sequence is reported. Most of these b...The damage to the masonry-infilled reinforced concrete( RC) frame buildings in Charikot,the capital city of Dolakha district in Nepal,during the 2015 April-to-May Nepal earthquake sequence is reported. Most of these buildings were built by the owners with little governmental inspections regarding their structural design or constructional quality. Although they generally performed better than other structural systems such as stone-masonry houses,the RC frames sustained extensive damage ranging from cracking of infill to complete collapse. In particular,eight of the 72 inspected RC frames alongside an uphill street collapsed in different ways. In addition to the un-engineered nature of these RC frames,their collapse could also be attributed to multiple technical reasons including the effect of terrain, the pounding between adjacent buildings and the accumulative damage in the earthquake sequence.展开更多
Pin-supported(PS)walls have been proven effective in avoiding weak story failure of frame structures by increasing the height-wise continuous stiffness and producing uniform distribution of story drifts.However,little...Pin-supported(PS)walls have been proven effective in avoiding weak story failure of frame structures by increasing the height-wise continuous stiffness and producing uniform distribution of story drifts.However,little attention has been given to the floor velocity or acceleration responses of PS wall-frame structures,which predominate the seismic damage of various nonstructural components that are critical to the immediate occupancy and quick recovery of buildings.This paper presents a numerical evaluation of the floor velocity and acceleration responses of PS wall-frame structures,highlighting the effects of different types of dampers accompanying the PS walls.The results show that the PS walls alone significantly increase the peak floor velocity(PFV)and peak floor acceleration(PFA)responses.PS wall-frame structures with either steel or viscoelastic(VE)dampers are much less effective in reducing the PFV or PFA responses than they are in reducing the peak inter-story drift ratio(PIDR).The impact of this behavior is demonstrated by a seismic fragility analysis that incorporates demand parameters combining the maximum PIDR,average PFV and PFA.The results show that the use of VE dampers rather than hysteretic dampers results in better protection of nonstructural components in PS wall-frame structures.展开更多
基金Research fund for earthquake engineering of China Earthquake Administration(201508023)a project of the National Science&Technology Support Program during the Twelfth Five-year Plan Period of China(2015BAK17B03)a general program of National Natural Science Foundation of China(51578515)
文摘Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.
基金the National Science and Technology Supporting Program(2012BAK15B02)the National Natural Science Foundation Program(50938006)the special program for Science Field Investigation on Lushan M7.0 Earthquake from the China Earthquake Administration
文摘Severe damage to steel space structures is rarely reported when compared to other structural systems damaged during past major earthquakes around the world. Two gymnasiums of steel space structures in downtown Lushan County that were damaged during the 2013 M7.0 Lushan earthquake in China were investigated and the observations are summarized in this paper. Typical damage to these two steel space structures ranges from moderate to severe. Moderate damage includes global buckling and dislocation of bolted connections of truss members, and inelastic elongation of anchor bolts and sliding of pedestal plates of supports. Severe damage includes member fracture caused by local buckling, and fracture failure of anchor bolts and welds. The distribution of structural damage to these two structures is described in detail and future research opportunities are suggested.
基金National Science & Technology Support Program during the Twelfth Five-year Plan Period of China under Grant No.2015BAK17B02,2015BAK17B03the Scientific Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2014A01+2 种基金the Program for Innovative Research Team in China Earthquake Administrationthe International Science & Technology Cooperation Program of China under Grant No.2014DFA70950a general program of National Natural Science Foundation of China under Grant No.51578515
文摘The seismic behavior of a school gymnasium, whose steel grid roof was heavily damaged during the Mw6.6 Lushan earthquake in 2013, is simulated through nonlinear dynamic analysis. The simulated damage is compared with field observations to validate the numerical model, based on which a parametric study was performed to provide insight into the failure process and damage patterns of steel grids. The results suggest that the grid damage is strongly related to roofsubstructure interactions. These include not only the substructure's amplification of the vibration, but the uncoordinated displacement of the substructure's columns which support the grid also play an equally important role. In particular, the latter effect may significantly alter the internal force distribution in the steel grid and lead to unexpected buckling of members that are proportioned as tension-only members. While such interactions are generally not accounted for in the design practice for grid structures in China, similar seismic damage may be expected for other existing grid roofs in future earthquakes. As is also demonstrated in this study, seismic isolation of the roof is a promising solution to protect grid roof structures by mitigating the detrimental effects of roof-substructure interactions.
基金jointly sponsored by the Scientific Research Fund of Engineering Mechanics,China Earthquake Administration(2016A05)the grant from the National Natural Science Foundation of China(51478441)
文摘The damage to the masonry-infilled reinforced concrete( RC) frame buildings in Charikot,the capital city of Dolakha district in Nepal,during the 2015 April-to-May Nepal earthquake sequence is reported. Most of these buildings were built by the owners with little governmental inspections regarding their structural design or constructional quality. Although they generally performed better than other structural systems such as stone-masonry houses,the RC frames sustained extensive damage ranging from cracking of infill to complete collapse. In particular,eight of the 72 inspected RC frames alongside an uphill street collapsed in different ways. In addition to the un-engineered nature of these RC frames,their collapse could also be attributed to multiple technical reasons including the effect of terrain, the pounding between adjacent buildings and the accumulative damage in the earthquake sequence.
基金National Natural Science Foundation of China under Grant No.51878629。
文摘Pin-supported(PS)walls have been proven effective in avoiding weak story failure of frame structures by increasing the height-wise continuous stiffness and producing uniform distribution of story drifts.However,little attention has been given to the floor velocity or acceleration responses of PS wall-frame structures,which predominate the seismic damage of various nonstructural components that are critical to the immediate occupancy and quick recovery of buildings.This paper presents a numerical evaluation of the floor velocity and acceleration responses of PS wall-frame structures,highlighting the effects of different types of dampers accompanying the PS walls.The results show that the PS walls alone significantly increase the peak floor velocity(PFV)and peak floor acceleration(PFA)responses.PS wall-frame structures with either steel or viscoelastic(VE)dampers are much less effective in reducing the PFV or PFA responses than they are in reducing the peak inter-story drift ratio(PIDR).The impact of this behavior is demonstrated by a seismic fragility analysis that incorporates demand parameters combining the maximum PIDR,average PFV and PFA.The results show that the use of VE dampers rather than hysteretic dampers results in better protection of nonstructural components in PS wall-frame structures.
