理想化结构单元法(ISU M )已经成为评估结构系统中承受载荷能力的一个有效工具。本文给出了最新的ISU M 板元公式,并考虑了双轴向推力和横向载荷对板元的加载。为了精确地模拟加筋板的性能,分别用梁—柱元和板元制作了肋材和板材的模型...理想化结构单元法(ISU M )已经成为评估结构系统中承受载荷能力的一个有效工具。本文给出了最新的ISU M 板元公式,并考虑了双轴向推力和横向载荷对板元的加载。为了精确地模拟加筋板的性能,分别用梁—柱元和板元制作了肋材和板材的模型。与有限元分析(FEA )的比较表明该方法对解决加筋板在横向压力和推力载荷下的问题是适用的。对箱形桁材的四点弯曲试验的分析表明与试验数据吻合良好。展开更多
Adaptive truss structures are a new kind of structures with integrated active members,whose dynamic characteristies can be beneficially modified to meet mission requirements.Active members containing actuating and sen...Adaptive truss structures are a new kind of structures with integrated active members,whose dynamic characteristies can be beneficially modified to meet mission requirements.Active members containing actuating and sensing units are the major components of adaptive truss structures.Modeling of adaptive truss structures is a key step to analyze the structural dynamic characteristics.A new experimental modal analysis approach,in which active members are used as excitatiDn sources for modal test,has been proposed in this paper.The excitation forces generated by the active members, which are different from the excitation forces exerted on structures in the conventional modal test,are internal forces for the truss structures.The relation between internal excitation forces and external forces is revealed such that the traditional identification method can be adopted to obtain modal parameters of adaptive structures.Placement problem of the active member in adaptive truss structures is also discussed in this work. Modal test and analysis are conducted with a planar adaptive truss structure by using piezoelectric active members in order to verify the feasibility and effectiveness of the proposed method.展开更多
Three types of composite stringers were impacted from two different directions.Relationships between impact energy and visible defect length were found.The critical impact energy corresponding to barely visible impact...Three types of composite stringers were impacted from two different directions.Relationships between impact energy and visible defect length were found.The critical impact energy corresponding to barely visible impact damage(BVID)of each stringer was determined.Specimens with BVID were then compressed to obtain the residual strength.Experimental results showed that for all types of stringers,the critical energy of in-plane impact is always much lower than out-plane ones.In-plane impact causes much more decrement of stringers'bearing capacity than outplane impact.For both impact directions,I-stringers own the highest defect detectability,T-stringers come second.Meanwhile,I-stringers own the better residual strength ratio than I-stringers and I-stringers.Synthetic considering impact defect detectability and residual bearing capacity after impact,T-stringers own the best compression-afterimpact(CAI)behaviors.展开更多
A numerical approach for simulating the seismic performance of steel truss structures, considering damage-induced material softening, is developed based on a ductile damage constitutive model by applying the backward ...A numerical approach for simulating the seismic performance of steel truss structures, considering damage-induced material softening, is developed based on a ductile damage constitutive model by applying the backward Euler explicit algorithm. It is implemented in ABAQUS through a user-defined material subroutine, by which damage evolution could be incorporated into the analysis of seismic performance of steel structures. The case study taken up here is the investigation of a steel connection with a reduced beam section(RBS) and a steel frame with such connections. The material softening effect during the failure process is particularly investigated. The results show that material softening in the vulnerable zone has a significant effect on the distribution of stress and strain fields, as well as on the carrying capacity of the steel connection with RBS. Further, material softening is found to have almost negligible effect on the seismic performance of the steel frame in the early stages of the loading process, but has a large effect when the steel frame is about to fail. These findings offer a practical reference for the assessment of seismic structural failure, and help in understanding the damage mechanism of steel structures under seismic loading.展开更多
With technical assistance from INBAR and the Research Institute of Wood Industry of the Chinese Academy of Forestry, the construction of the Pingbian Primary School was completed in 2004, where bamboo plywood panels a...With technical assistance from INBAR and the Research Institute of Wood Industry of the Chinese Academy of Forestry, the construction of the Pingbian Primary School was completed in 2004, where bamboo plywood panels and laminated beams were used for the roof trusses, sheathing boards and wall panels. This is the first time that bamboo-based panels are used for structural applications.展开更多
文摘理想化结构单元法(ISU M )已经成为评估结构系统中承受载荷能力的一个有效工具。本文给出了最新的ISU M 板元公式,并考虑了双轴向推力和横向载荷对板元的加载。为了精确地模拟加筋板的性能,分别用梁—柱元和板元制作了肋材和板材的模型。与有限元分析(FEA )的比较表明该方法对解决加筋板在横向压力和推力载荷下的问题是适用的。对箱形桁材的四点弯曲试验的分析表明与试验数据吻合良好。
文摘Adaptive truss structures are a new kind of structures with integrated active members,whose dynamic characteristies can be beneficially modified to meet mission requirements.Active members containing actuating and sensing units are the major components of adaptive truss structures.Modeling of adaptive truss structures is a key step to analyze the structural dynamic characteristics.A new experimental modal analysis approach,in which active members are used as excitatiDn sources for modal test,has been proposed in this paper.The excitation forces generated by the active members, which are different from the excitation forces exerted on structures in the conventional modal test,are internal forces for the truss structures.The relation between internal excitation forces and external forces is revealed such that the traditional identification method can be adopted to obtain modal parameters of adaptive structures.Placement problem of the active member in adaptive truss structures is also discussed in this work. Modal test and analysis are conducted with a planar adaptive truss structure by using piezoelectric active members in order to verify the feasibility and effectiveness of the proposed method.
基金supported in part by the National Key Basic Research and Development Plan (“973”Plan)(No. 613274)Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Three types of composite stringers were impacted from two different directions.Relationships between impact energy and visible defect length were found.The critical impact energy corresponding to barely visible impact damage(BVID)of each stringer was determined.Specimens with BVID were then compressed to obtain the residual strength.Experimental results showed that for all types of stringers,the critical energy of in-plane impact is always much lower than out-plane ones.In-plane impact causes much more decrement of stringers'bearing capacity than outplane impact.For both impact directions,I-stringers own the highest defect detectability,T-stringers come second.Meanwhile,I-stringers own the better residual strength ratio than I-stringers and I-stringers.Synthetic considering impact defect detectability and residual bearing capacity after impact,T-stringers own the best compression-afterimpact(CAI)behaviors.
文摘A numerical approach for simulating the seismic performance of steel truss structures, considering damage-induced material softening, is developed based on a ductile damage constitutive model by applying the backward Euler explicit algorithm. It is implemented in ABAQUS through a user-defined material subroutine, by which damage evolution could be incorporated into the analysis of seismic performance of steel structures. The case study taken up here is the investigation of a steel connection with a reduced beam section(RBS) and a steel frame with such connections. The material softening effect during the failure process is particularly investigated. The results show that material softening in the vulnerable zone has a significant effect on the distribution of stress and strain fields, as well as on the carrying capacity of the steel connection with RBS. Further, material softening is found to have almost negligible effect on the seismic performance of the steel frame in the early stages of the loading process, but has a large effect when the steel frame is about to fail. These findings offer a practical reference for the assessment of seismic structural failure, and help in understanding the damage mechanism of steel structures under seismic loading.
文摘With technical assistance from INBAR and the Research Institute of Wood Industry of the Chinese Academy of Forestry, the construction of the Pingbian Primary School was completed in 2004, where bamboo plywood panels and laminated beams were used for the roof trusses, sheathing boards and wall panels. This is the first time that bamboo-based panels are used for structural applications.
