To study the influence of construction interfaces on dynamic characteristics of roller compacted concrete dams(RCCDs),mechanical properties of construction interfaces are firstly analyzed. Then, the viscous-spring art...To study the influence of construction interfaces on dynamic characteristics of roller compacted concrete dams(RCCDs),mechanical properties of construction interfaces are firstly analyzed. Then, the viscous-spring artificial boundary(VSAB) is adopted to simulate the radiation damping of their infinite foundations, and based on the Marc software, a simplified seismic motion input method is presented by the equivalent nodal loads. Finally, based on the practical engineering of a RCC gravity dam, effects of radiation damping and construction interfaces on the dynamic characteristics of dams are investigated in detail. Analysis results show that dynamic response of the RCC gravity dam significantly reduces about 25% when the radiation damping of infinite foundation is considered. Hot interfaces and the normal cold interfaces have little influence on the dynamic response of the RCC gravity dam.However, nonlinear fracture along the cold interfaces at the dam heel will occur under the designed earthquake if the cold interfaces are combined poorly. Therefore, to avoid the fractures along the construction interfaces under the potential super earthquakes,combination quality of the RCC layers should be significantly ensured.展开更多
In 2007,over 24 million tons of Construction and Demolition(C&D) wastes were generated in Hong Kong.Since the local landfills will be saturated in about 6 years,it is important to find a viable way to reuse these ...In 2007,over 24 million tons of Construction and Demolition(C&D) wastes were generated in Hong Kong.Since the local landfills will be saturated in about 6 years,it is important to find a viable way to reuse these waste materials as to alleviate the demand on public fill capacity.In order to tackle the problem,the Hong Kong government has set up a temporary recycling facility in Hong Kong in 2002 for producing different sizes of recycled aggregate for use in various construction materials.The Hong Kong Polytechnic University has been studying the feasible use of recycled aggregates in Hong Kong for a number of years.A substantial amount of experimental results on the properties of recycled aggregates and the effect of recycled aggregates on the properties of concrete and other construction products(e.g.concrete blocks and granular sub-base) has been published.In this paper,the experience of Hong Kong in using recycled aggregates are summarized and a set of quality control guidelines proposed for governing the use of recycled aggregates in Hong Kong is introduced.The experience and guidelines may also be useful for the recycling of waste materials derived from the recent Sichuan earthquake in China.展开更多
The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on sin...The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.展开更多
In the construction of Three Gorges Project, the total amount of concrete is about 28 Mm\+3 , and the total amount of metal works and reinforcement is approximately 0.72 Mt . The TGP is constructed in 3 stages . The p...In the construction of Three Gorges Project, the total amount of concrete is about 28 Mm\+3 , and the total amount of metal works and reinforcement is approximately 0.72 Mt . The TGP is constructed in 3 stages . The preparation period together with the first stage is 5 years , the second stage and third stage are both 6 years .In the second stage construction of 6 years (1998～2003) , there are 18.46 Mm\+3 of concrete to be placed and 0.192 Mt of metal works and embedded parts for mechanical and electric equipment to be installed . In 1999, a world record of annual concrete placement of 4.585 Mm\+3 was set . In 2000, it is planned to place 5.4 Mm\+3 of concrete and to install 38 000 t of metal works . Construction equipments and layout of construction site , concrete production and its temperature control, metal works, mechanical and electric equipments in the second stage construction are presented.展开更多
The special reinforced concrete composite beam consists of a steel fiber reinforced self-stressing concrete composite layer and a reinforced concrete T-beam, and constructional bars are set up at their bonding interfa...The special reinforced concrete composite beam consists of a steel fiber reinforced self-stressing concrete composite layer and a reinforced concrete T-beam, and constructional bars are set up at their bonding interface. Fatigue properties of the composite beam under the action of negative moment were experimentally studied. Through inverted loading mode the load-beating state of a composite beam was simulated under the action of negative moment. With the ratios of constructional bars being 0, 0.082% and 0.164% respectively as parameters, the effects of constructional bars on the properties of composite beam, such as fatigue life, crack propagation, rigidity loss as well as damage behavior of bonding interface, were studied. The mechanism of the constructional bars on the fatigue properties of the composite beams and the restriction mechanism of crack widths and rigidity loss were analyzed. The test results show that the constructional bars can enhance the shear resistance of the bonding interface between composite layer and old concrete beam and restrict expanding of steel fiber reinforced self-stressing concrete, which are beneficial to synergistic action of composite layer and old concrete beam, to reducing the stress amplitude of bars and the crack width of composite layer, and to increasing the durability and fatigue life of the composite beam.展开更多
利用超高性能混凝土(ultra high performance concrete, UHPC)材料特性,提出一种针对预制拼装桥墩的重力灌浆构造,即采用UHPC灌浆并依靠立柱自身重力完成拼接的插槽式连接构造。为研究该形式桥墩的抗震性能,设计完成了三个桥墩的拟静力...利用超高性能混凝土(ultra high performance concrete, UHPC)材料特性,提出一种针对预制拼装桥墩的重力灌浆构造,即采用UHPC灌浆并依靠立柱自身重力完成拼接的插槽式连接构造。为研究该形式桥墩的抗震性能,设计完成了三个桥墩的拟静力试验,分别为整体现浇墩Z1、新型插槽式连接墩P1及现有“I型”连接墩P2,并采用OpenSees有限元软件做模拟分析,与试验结果对比分析。结果表明:三个桥墩的破坏形式一致,均为弯曲破坏;Z1墩与P1墩滞回曲线呈梭形,滞回环较为饱满,且相同位移加载循环下的滞回路径较为吻合,P2墩接口处钢筋与混凝土间黏结滑移影响较大,导致滞回环面积减小,桥墩整体滞回耗能能力降低;P1墩的耗能能力较Z1墩和P2墩分别提升7.0%、10.7%,呈现峰值荷载小、失效速率慢、极限位移大、滞回耗能多的骨架趋势。试验结果与有限元模拟结果较为吻合,抗震性能参数差幅在10.0%以内,新型插槽式连接墩可应用于实际工程。展开更多
基金Projects(20120094110005,20120094130003)supported by the Research Fund for the Doctoral Program of Higher Education of ChinaProjects(51379068,51139001,51279052,51209077,51179066)supported by the National Natural Science Foundation of China+1 种基金Project(NCET-11-0628)supported by the Program for New Century Excellent Talents in University,ChinaProjects(201201038,201101013)supported by the Public Welfare Industry Research Special Fund Project of Ministry of Water Resources of China
文摘To study the influence of construction interfaces on dynamic characteristics of roller compacted concrete dams(RCCDs),mechanical properties of construction interfaces are firstly analyzed. Then, the viscous-spring artificial boundary(VSAB) is adopted to simulate the radiation damping of their infinite foundations, and based on the Marc software, a simplified seismic motion input method is presented by the equivalent nodal loads. Finally, based on the practical engineering of a RCC gravity dam, effects of radiation damping and construction interfaces on the dynamic characteristics of dams are investigated in detail. Analysis results show that dynamic response of the RCC gravity dam significantly reduces about 25% when the radiation damping of infinite foundation is considered. Hot interfaces and the normal cold interfaces have little influence on the dynamic response of the RCC gravity dam.However, nonlinear fracture along the cold interfaces at the dam heel will occur under the designed earthquake if the cold interfaces are combined poorly. Therefore, to avoid the fractures along the construction interfaces under the potential super earthquakes,combination quality of the RCC layers should be significantly ensured.
文摘In 2007,over 24 million tons of Construction and Demolition(C&D) wastes were generated in Hong Kong.Since the local landfills will be saturated in about 6 years,it is important to find a viable way to reuse these waste materials as to alleviate the demand on public fill capacity.In order to tackle the problem,the Hong Kong government has set up a temporary recycling facility in Hong Kong in 2002 for producing different sizes of recycled aggregate for use in various construction materials.The Hong Kong Polytechnic University has been studying the feasible use of recycled aggregates in Hong Kong for a number of years.A substantial amount of experimental results on the properties of recycled aggregates and the effect of recycled aggregates on the properties of concrete and other construction products(e.g.concrete blocks and granular sub-base) has been published.In this paper,the experience of Hong Kong in using recycled aggregates are summarized and a set of quality control guidelines proposed for governing the use of recycled aggregates in Hong Kong is introduced.The experience and guidelines may also be useful for the recycling of waste materials derived from the recent Sichuan earthquake in China.
基金Project (2007H03) supported by Communications Department of Zhejiang Province
文摘The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.
文摘In the construction of Three Gorges Project, the total amount of concrete is about 28 Mm\+3 , and the total amount of metal works and reinforcement is approximately 0.72 Mt . The TGP is constructed in 3 stages . The preparation period together with the first stage is 5 years , the second stage and third stage are both 6 years .In the second stage construction of 6 years (1998～2003) , there are 18.46 Mm\+3 of concrete to be placed and 0.192 Mt of metal works and embedded parts for mechanical and electric equipment to be installed . In 1999, a world record of annual concrete placement of 4.585 Mm\+3 was set . In 2000, it is planned to place 5.4 Mm\+3 of concrete and to install 38 000 t of metal works . Construction equipments and layout of construction site , concrete production and its temperature control, metal works, mechanical and electric equipments in the second stage construction are presented.
基金Project(50578027) supported by the National Natural Science Foundation of China
文摘The special reinforced concrete composite beam consists of a steel fiber reinforced self-stressing concrete composite layer and a reinforced concrete T-beam, and constructional bars are set up at their bonding interface. Fatigue properties of the composite beam under the action of negative moment were experimentally studied. Through inverted loading mode the load-beating state of a composite beam was simulated under the action of negative moment. With the ratios of constructional bars being 0, 0.082% and 0.164% respectively as parameters, the effects of constructional bars on the properties of composite beam, such as fatigue life, crack propagation, rigidity loss as well as damage behavior of bonding interface, were studied. The mechanism of the constructional bars on the fatigue properties of the composite beams and the restriction mechanism of crack widths and rigidity loss were analyzed. The test results show that the constructional bars can enhance the shear resistance of the bonding interface between composite layer and old concrete beam and restrict expanding of steel fiber reinforced self-stressing concrete, which are beneficial to synergistic action of composite layer and old concrete beam, to reducing the stress amplitude of bars and the crack width of composite layer, and to increasing the durability and fatigue life of the composite beam.
文摘利用超高性能混凝土(ultra high performance concrete, UHPC)材料特性,提出一种针对预制拼装桥墩的重力灌浆构造,即采用UHPC灌浆并依靠立柱自身重力完成拼接的插槽式连接构造。为研究该形式桥墩的抗震性能,设计完成了三个桥墩的拟静力试验,分别为整体现浇墩Z1、新型插槽式连接墩P1及现有“I型”连接墩P2,并采用OpenSees有限元软件做模拟分析,与试验结果对比分析。结果表明:三个桥墩的破坏形式一致,均为弯曲破坏;Z1墩与P1墩滞回曲线呈梭形,滞回环较为饱满,且相同位移加载循环下的滞回路径较为吻合,P2墩接口处钢筋与混凝土间黏结滑移影响较大,导致滞回环面积减小,桥墩整体滞回耗能能力降低;P1墩的耗能能力较Z1墩和P2墩分别提升7.0%、10.7%,呈现峰值荷载小、失效速率慢、极限位移大、滞回耗能多的骨架趋势。试验结果与有限元模拟结果较为吻合,抗震性能参数差幅在10.0%以内,新型插槽式连接墩可应用于实际工程。
