Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a ...Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a strokelimited AMD control system with a fixed limited area shortens the available AMD stroke and leads to significant control power.To solve this problem,the design approach with variable gain and limited area(VGLA)is proposed in this study.First,the boundary of variable-limited areas is calculated based on the real-time status of the moving mass.The variable gain(VG)expression at the variable limited area is deduced by considering the saturation of AMD stroke.Then,numerical simulations of a stroke-limited AMD control system with VGLA are conducted on a high-rise building structure.These numerical simulations show that the proposed approach has superior strokelimitation performance compared with a stroke-limited AMD control system with a fixed limited area.Finally,the proposed approach is validated through experiments on a four-story steel frame.展开更多
The design code for each country is revised and updated based on an expected zone’s seismic intensities,geotechnical site classifications,structural systems,construction materials and methods of construction in order...The design code for each country is revised and updated based on an expected zone’s seismic intensities,geotechnical site classifications,structural systems,construction materials and methods of construction in order to provide more realistic considerations of seismic demand,seismic response,and seismic capacity.Based on the aforementioned provisions,structures designed according to different seismic codes may yield different performances for the same level of hazard.This study aims to investigate and compare the induced responses related to the earthquake-resistant design of reinforced concrete(RC)buildings according to the Saudi building code(SBC-301),American code(ASCE-7),uniform building code(UBC-97),and European code(EC-8).In order to account for the provision regarding the hazard specification and its effect on the induced seismic responses,four regions in the Kingdom of Saudi Arabia with different seismic levels are selected.The code provisions related to the specification of site classification and its effect on the induced design base shear are investigated as well.Significant differences are observed in the induced responses with the variation in seismic design codes for the considered seismic hazards and site classifications.展开更多
To improve the performance of an active mass damper control system,the controller should be designed based on a reduced-order model. An improved method based on balanced truncation method was proposed to reduce the di...To improve the performance of an active mass damper control system,the controller should be designed based on a reduced-order model. An improved method based on balanced truncation method was proposed to reduce the dimension of high-rise buildings,and was compared with other widely used reduction methods by using a framework with ten floors. This optimized method has improvement of reduction process and choice of the order. Based on the reduced-order model obtained by the improved method and pole-assignment algorithm,a controller was designed. Finally,a comparative analysis of structural responses,transfer functions,and poles was conducted on an actual high-rise building. The results show the effectiveness of the improved method.展开更多
The paper is a contribution to the technical discussion concerning the collapses of the WTC buildings. It returns to the problem of the dynamics of the collapses;it does not concern the reason why the buildings starte...The paper is a contribution to the technical discussion concerning the collapses of the WTC buildings. It returns to the problem of the dynamics of the collapses;it does not concern the reason why the buildings started collapsing, but investigates the dynamics of the collapse itself. It works with the same assumptions as the official NIST report [1], i.e. that the falling mass hits the motionless mass beneath;the supporting columns loose stability and the mass of the pertinent floor starts to fall together with the falling mass. The aim was to derive the theoretical upper limit of the speed of the collapse, supposing that influence of the columns which resist the fall, is neglected. The differential equation of the fall was obtained using two independent laws of mechanics, with the identical result. Its solution can be found from a very simple explicit formula. The theoretical upper limit acceleration of the fall obtained by such formula is one third of the gravitational acceleration, which is faster than it was observed in the case of the collapses of WTC1 and WTC2. This leads to the conclusion that the mechanism of the collapse must be different from the assumed and the falling mass must not hit the motionless mass bellow it, but rather a mass which had started to fall before the impact of the falling mass occurred.展开更多
The field of earthquake engineering and seismology is of great importance to structural engineers around the world. The location, size and consequences of an earthquake are variable depending on several conditions. Su...The field of earthquake engineering and seismology is of great importance to structural engineers around the world. The location, size and consequences of an earthquake are variable depending on several conditions. Surface conditions, boundary/fault type, distance from the boundary and hypocenter are all elements that dictate the outcome of a seismic event. The paper presents a comparison of seismic provisions of two seismic design codes--EC8 （Eurocode 8） and IBC （International Building Code） 2006, to a high-rise reinforced concrete building. The building is irregular and composes of 20 floors. The equivalent lateral force analysis was performed using the well-known structure program--ETABS （Extended 3D Analysis of Building Systems）. Based on the analysis results （inter-storey index, global damage index, storey displacement, inter-storey drift ratio and base shear）, EC8 was found to be conservative when compared with IBC 2006. The conclusion is that for the design and analysis of high-rise reinforced concrete buildings with certain irregularity, EC8 provisions were considered to be conservative.展开更多
益中花园1号楼为一超高层住宅,地上50层,建筑高度177.85m,采用全部落地剪力墙结构体系,超过 B 级最大适用高度18.5%。针对结构高度超限,采取了基于性能的抗震设计和比现行规范要求更为严格的抗震措施。采用 SATWE,PMSAP,ETABS 程序对结...益中花园1号楼为一超高层住宅,地上50层,建筑高度177.85m,采用全部落地剪力墙结构体系,超过 B 级最大适用高度18.5%。针对结构高度超限,采取了基于性能的抗震设计和比现行规范要求更为严格的抗震措施。采用 SATWE,PMSAP,ETABS 程序对结构进行多遇地震作用下的计算并对整体结构进行了弹性动力时程补充计算和罕遇地震作用下静力弹塑性分析。结果表明,工程抗震性能较好,结构体系安全可行。展开更多
基金This research was founded by the Funds for Creative Research Groups of National Natural Science Foundation of China(Grant No.51921006)the National Natural Science Foundations of China(Grant No.51978224)+2 种基金the National Major Scientific Research Instrument Development Program of China(Grant No.51827811)the National Natural Science Foundation of China,(Grant No.52008141)the Shenzhen Technology Innovation Program(Grant Nos.JCYJ20170811160003571,JCYJ20180508152238111 and JCYJ20200109112803851).
文摘Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a strokelimited AMD control system with a fixed limited area shortens the available AMD stroke and leads to significant control power.To solve this problem,the design approach with variable gain and limited area(VGLA)is proposed in this study.First,the boundary of variable-limited areas is calculated based on the real-time status of the moving mass.The variable gain(VG)expression at the variable limited area is deduced by considering the saturation of AMD stroke.Then,numerical simulations of a stroke-limited AMD control system with VGLA are conducted on a high-rise building structure.These numerical simulations show that the proposed approach has superior strokelimitation performance compared with a stroke-limited AMD control system with a fixed limited area.Finally,the proposed approach is validated through experiments on a four-story steel frame.
文摘The design code for each country is revised and updated based on an expected zone’s seismic intensities,geotechnical site classifications,structural systems,construction materials and methods of construction in order to provide more realistic considerations of seismic demand,seismic response,and seismic capacity.Based on the aforementioned provisions,structures designed according to different seismic codes may yield different performances for the same level of hazard.This study aims to investigate and compare the induced responses related to the earthquake-resistant design of reinforced concrete(RC)buildings according to the Saudi building code(SBC-301),American code(ASCE-7),uniform building code(UBC-97),and European code(EC-8).In order to account for the provision regarding the hazard specification and its effect on the induced seismic responses,four regions in the Kingdom of Saudi Arabia with different seismic levels are selected.The code provisions related to the specification of site classification and its effect on the induced design base shear are investigated as well.Significant differences are observed in the induced responses with the variation in seismic design codes for the considered seismic hazards and site classifications.
文摘To improve the performance of an active mass damper control system,the controller should be designed based on a reduced-order model. An improved method based on balanced truncation method was proposed to reduce the dimension of high-rise buildings,and was compared with other widely used reduction methods by using a framework with ten floors. This optimized method has improvement of reduction process and choice of the order. Based on the reduced-order model obtained by the improved method and pole-assignment algorithm,a controller was designed. Finally,a comparative analysis of structural responses,transfer functions,and poles was conducted on an actual high-rise building. The results show the effectiveness of the improved method.
基金supported from the project of Ministry of Educa-tion,Youth and Sports of the Czech Republic AdMaS UP(Advanced Materials,Structures and Technologies),National Sustainability Programme I,LO1408.
文摘The paper is a contribution to the technical discussion concerning the collapses of the WTC buildings. It returns to the problem of the dynamics of the collapses;it does not concern the reason why the buildings started collapsing, but investigates the dynamics of the collapse itself. It works with the same assumptions as the official NIST report [1], i.e. that the falling mass hits the motionless mass beneath;the supporting columns loose stability and the mass of the pertinent floor starts to fall together with the falling mass. The aim was to derive the theoretical upper limit of the speed of the collapse, supposing that influence of the columns which resist the fall, is neglected. The differential equation of the fall was obtained using two independent laws of mechanics, with the identical result. Its solution can be found from a very simple explicit formula. The theoretical upper limit acceleration of the fall obtained by such formula is one third of the gravitational acceleration, which is faster than it was observed in the case of the collapses of WTC1 and WTC2. This leads to the conclusion that the mechanism of the collapse must be different from the assumed and the falling mass must not hit the motionless mass bellow it, but rather a mass which had started to fall before the impact of the falling mass occurred.
文摘The field of earthquake engineering and seismology is of great importance to structural engineers around the world. The location, size and consequences of an earthquake are variable depending on several conditions. Surface conditions, boundary/fault type, distance from the boundary and hypocenter are all elements that dictate the outcome of a seismic event. The paper presents a comparison of seismic provisions of two seismic design codes--EC8 （Eurocode 8） and IBC （International Building Code） 2006, to a high-rise reinforced concrete building. The building is irregular and composes of 20 floors. The equivalent lateral force analysis was performed using the well-known structure program--ETABS （Extended 3D Analysis of Building Systems）. Based on the analysis results （inter-storey index, global damage index, storey displacement, inter-storey drift ratio and base shear）, EC8 was found to be conservative when compared with IBC 2006. The conclusion is that for the design and analysis of high-rise reinforced concrete buildings with certain irregularity, EC8 provisions were considered to be conservative.
文摘益中花园1号楼为一超高层住宅,地上50层,建筑高度177.85m,采用全部落地剪力墙结构体系,超过 B 级最大适用高度18.5%。针对结构高度超限,采取了基于性能的抗震设计和比现行规范要求更为严格的抗震措施。采用 SATWE,PMSAP,ETABS 程序对结构进行多遇地震作用下的计算并对整体结构进行了弹性动力时程补充计算和罕遇地震作用下静力弹塑性分析。结果表明,工程抗震性能较好,结构体系安全可行。
