In the context of global emission reduction, the low-carbon sustainable development of the construction industry has become an important research content. With the vigorous development of new industrial technologies, ...In the context of global emission reduction, the low-carbon sustainable development of the construction industry has become an important research content. With the vigorous development of new industrial technologies, the application of prefabrication technology to buildings had become a mainstream. However, the research on the role of prefabricated technology in reducing building carbon emissions was not yet comprehensive, and the research on the relationship between prefabricated structure types and carbon emissions in the construction stage was not yet thorough. Guided by life cycle assessment (LCA), this paper used the scenario analysis method to set different working conditions for five different structural systems, and used SimaPro software to evaluate the carbon emissions of prefabricated buildings in order to clarify the carbon emissions of prefabricated buildings under different structural systems, and explore their impact mechanisms in depth. Finally, take the existing buildings in China as an empirical study, the results showed that: 1) The carbon emissions produced by the four common prefabricated structural systems were almost the same. Different structures had different requirements for the combination of components. The carbon emissions of individual buildings would be superimposed according to the carbon emission characteristics of various individual components to form the final total carbon emissions. 2) When the building structure system requires more combinations of components, the greater the amount of transportation invested in the transportation process, the more carbon emissions would be caused. In the calculation of all individual building construction stages, the carbon emissions generated by tower cranes almost exceed the sum of the carbon emissions of all mobile machinery. 3) Prefabricated shear wall structures and prefabricated frame-shear wall structures require a large amount of hoisting of prefabricated shear walls, so the carbon emissions of their mechanical equipment were also the highest.展开更多
The offset of geological bodies provides robust evidence of displacement along a fault or ductile shear zone. The amount of displacement along the Xuelongshan–Diancangshan–Ailaoshan structural system, southeastern T...The offset of geological bodies provides robust evidence of displacement along a fault or ductile shear zone. The amount of displacement along the Xuelongshan–Diancangshan–Ailaoshan structural system, southeastern Tibetan Plateau, is uncertain because of the lack of offset geological markers. This NNW–SSE-trending system is developed in three isolated metamorphic complexes and interjacent nonmetamorphosed rocks. They are expected to record similar post-Eocene strain, although their structural patterns should be distinct. Geological mapping in the area between the Xuelongshan and Diancangshan metamorphic complexes has revealed a small Eocene basin, the Madeng Basin, located to the west of the structural system. The sedimentary and volcanic successions of the Madeng Basin are comparable to those of the Jianchuan Basin, which is located to the east of the structural system. Zircon U–Pb geochronological and bulk geochemical data demonstrate that the volcanic rocks of both basins formed during 37–34 Ma and share the same geochemical features. These data suggest that the Madeng and Jianchuan basins previously constituted a single basin, with the distribution of high-K volcanic rocks in the basins defining an ENE–WSW-trending volcanic belt that shows a limited dextral offset of ≤20 km across the Xuelongshan–Diancangshan–Ailaoshan structural system. Therefore, the northern segment of the structural system records no evidence of large-scale lateral movement/displacement. The results suggest that the Indochina block, which is bounded by the Xuelongshan–Diancangshan–Ailaoshan structural system to the east and the Sagaing Fault to the west, has not extruded southward as a whole but rather has been deformed by pervasive crustal shortening.展开更多
The structural system failure probability(SFP) is a valuable tool for evaluating the global safety level of concrete gravity dams.Traditional methods for estimating the failure probabilities are based on defined mathe...The structural system failure probability(SFP) is a valuable tool for evaluating the global safety level of concrete gravity dams.Traditional methods for estimating the failure probabilities are based on defined mathematical descriptions,namely,limit state functions of failure modes.Several problems are to be solved in the use of traditional methods for gravity dams.One is how to define the limit state function really reflecting the mechanical mechanism of the failure mode;another is how to understand the relationship among failure modes and enable the probability of the whole structure to be determined.Performing SFP analysis for a gravity dam system is a challenging task.This work proposes a novel nonlinear finite-element-based SFP analysis method for gravity dams.Firstly,reasonable nonlinear constitutive modes for dam concrete,concrete/rock interface and rock foundation are respectively introduced according to corresponding mechanical mechanisms.Meanwhile the response surface(RS) method is used to model limit state functions of main failure modes through the Monte Carlo(MC) simulation results of the dam-interface-foundation interaction finite element(FE) analysis.Secondly,a numerical SFP method is studied to compute the probabilities of several failure modes efficiently by simple matrix integration operations.Then,the nonlinear FE-based SFP analysis methodology for gravity dams considering correlated failure modes with the additional sensitivity analysis is proposed.Finally,a comprehensive computational platform for interfacing the proposed method with the open source FE code Code Aster is developed via a freely available MATLAB software tool(FERUM).This methodology is demonstrated by a case study of an existing gravity dam analysis,in which the dominant failure modes are identified,and the corresponding performance functions are established.Then,the dam failure probability of the structural system is obtained by the proposed method considering the correlation relationship of main failure modes on the basis of the mechanical mechanism analysis with the MC-FE simulations.展开更多
The problem of robust active vibration control for a class of electro-hydraulic actuated structural systems with time-delay in the control input channel and parameter uncertainties appearing in all the mass, damping a...The problem of robust active vibration control for a class of electro-hydraulic actuated structural systems with time-delay in the control input channel and parameter uncertainties appearing in all the mass, damping and stiffness matrices is investigated in this paper. First, by introducing a linear varying parameter, the nonlinear system is described as a linear parameter varying （LPV） model. Second, based on this LPV model, an LMI-based condition for the system to be asymptotically stabilized is deduced. By solving these LMIs, a parameter-dependent controller is established for the closed- loop system to be stable with a prescribed level of disturbance attenuation. The condition is also extended to the uncertain case. Finally, some numerical simulations demonstrate the satisfying performance of the proposed controller.展开更多
Due to the shortage of land in cities and population growth,the significance of high rise buildings has risen.Controlling lateral displacement of structures under different loading such as an earthquake is an importan...Due to the shortage of land in cities and population growth,the significance of high rise buildings has risen.Controlling lateral displacement of structures under different loading such as an earthquake is an important issue for designers.One of the best systems is the diagrid method which is built with diagonal elements with no columns for manufacturing tall buildings.In this study,the effect of the distribution of the tuned mass damper(TMD)on the structural responses of diagrid tall buildings was investigated using a new dynamic method.So,a diagrid structural systems with variable height with TMDs was solved as an example of structure.The reason for the selection of the diagrid system was the formation of a stiffness matrix for the diagonal and angular elements.Therefore,the effect of TMDs distribution on the story drift,base shear and structural behaviour were studied.The obtained outcomes showed that the TMDs distribution does not significantly affect on improving the behaviour of the diagrid structural system during an earthquake.Furthermore,the new dynamic scheme represented in this study has good performance for analyzing different systems.Abbreviation:TMD-tuned mass damper;SATMD-semiactive-tuned mass dampers;MDOF-multiple degrees of freedom;m_(i)-mass of ith story of the building;c_(i)-damping coefficient of the ith story of the building;k_(i)-stiffness of ith story of the building;x_(i)-displacement of the ith story of the building;md-mass of damper;c_(d)-damping coefficient of the damper;k_(d)-stiffness of damper;x_(d)-displacement of TMD;M_(i)-generalized mass of the ith normal mode;C_(i)-generalized damping of the ith normal mode;K_(i)-generalized stiffness of the ith normal mode;K_(i)(t)-generalized load of the ith normal mode;Y_(i)(t)-generalized displacement of the ith normal mode;[M]-matrices of mass;[C]-matrices of damping;{P(t)}-consequence external forces;N_(i)(τ)-interpolation functions;[Ai]-mechanical properties of the structure.展开更多
The problem of active vibration control for uncertain linear structural systems with control forces input timedelay is investigated in this study.First,the original structural equation is converted to a state-space mo...The problem of active vibration control for uncertain linear structural systems with control forces input timedelay is investigated in this study.First,the original structural equation is converted to a state-space model by utilizing the matrix transformation.Second,according to the obtained model and a special Lyapunov functional,a sufficient condition is achieved for the closed-loop system to be stable with a prescribed level of disturbance attenuation.Then,in terms of solving these linear matrix inequalities（LMIs）,the state-feed controller is achieved to stabilize the structural system with the performance ‖z‖2<γ‖ω‖2.Third,by introducing the rank-1 vector to describe the system uncertainties,the uncertain system description is obtained,and the stabilizing condition is extended to the uncertain case.Finally,examples are given to show the effectiveness of the proposed methods.展开更多
Sutong Bridge,whose layout is [(100+100+300)+1 088 +(300+100+100)] m,marks the largest span of cable-stayed bridges in the world.The complex natural condition at the bridge site and the strict requirements for resista...Sutong Bridge,whose layout is [(100+100+300)+1 088 +(300+100+100)] m,marks the largest span of cable-stayed bridges in the world.The complex natural condition at the bridge site and the strict requirements for resistance of wind and seismic action make it crucial to choose a favorable structural system to assure the function and safety of the bridge.The comparison among several optional structural systems for Sutong Bridge is illustrated.After detailed analysis is carried out for viscous damper and hydraulic buffer,super liquid viscous damper with additional displacement limitation is designed for the first application in bridge engineering.The parameters for the damper is analyzed and studied and the dampers are installed successfully after quality tests.展开更多
The paper presents a selected group of tension-strut structural systems designed for the construction of lightweight dome covers of large spans, which can be comparatively easy to assembly and have rises of which can ...The paper presents a selected group of tension-strut structural systems designed for the construction of lightweight dome covers of large spans, which can be comparatively easy to assembly and have rises of which can be relatively small. This will allow significant decrease costs of erection and maintenance of objects covered by these roof structures. The proposed systems have been obtained from the results of suitable transformations of a chosen type of double-layer space frame and an appropriate arrangement of tetrahedron modules in the space of each of the newly designed type of the structural system. All these systems are built by means of concentric hoops having their own integral spatial stiffness obtained after an appropriate pre-stressing. Particular hoops can be mounted on the ground level and then one by one will be hoisted to the designed positions where they will be connected by means of special sets of the tension members. Due to these structural features, the assembly process of each system should be relatively simple, fast and not expensive. The whole tension-strut structure has to be connected to the compression perimeter ring and suitably pre-stressed. There are presented visualizations of the proposed systems prepared on the basis of the appropriate numerical models especially defined for each particular structure.展开更多
In order to investigate the behavior of buildings and engineering structures during earthquakes, based on the data of seismic observation devices mounted on constructions with typical characteristics, results of inves...In order to investigate the behavior of buildings and engineering structures during earthquakes, based on the data of seismic observation devices mounted on constructions with typical characteristics, results of investigating the change of mechanical properties of building structural system over time and the results of examination of structural rigidity and safety change over time, depending on the dynamic characteristics of the building, determined by experimental investigations made at intervals are mentioned in this article. In addition, evaluation of earthquake acceleration acting on structures due to earthquake-induced damage characteristics of buildings and engineering constructions which are made earthquake resistant is also included here.展开更多
General regular shaped diagrid structures can express diverse shapes because braces are installed along the exterior faces of the structures and the structures have no columns. However, since irregular shaped structur...General regular shaped diagrid structures can express diverse shapes because braces are installed along the exterior faces of the structures and the structures have no columns. However, since irregular shaped structures have diverse variables, studies to assess behaviors resulting from various variables are continuously required to supplement the imperfections related to such variables. In the present study, materials elastic modulus and yield strength were selected as variables for strength that would be applied to diagrid structural systems in the form of Twisters among the irregular shaped buildings classified by Vollers and that affect the structural design of these structural systems. The purpose of this study is to conduct sensitivity analysis for axial rotation diagrid structural systems according to changes in brace angles in order to identify the design variables that have relatively larger effects and the tendencies of the sensitivity of the structures according to changes in brace angles and axial rotation angles.展开更多
A system reliability estimation method for spatial jacket platforms is developed in this paper. The jacket platform is modeled into three-dimensional assembly of spatial beam and plate elements in Finite Element Metho...A system reliability estimation method for spatial jacket platforms is developed in this paper. The jacket platform is modeled into three-dimensional assembly of spatial beam and plate elements in Finite Element Method (FEM). The limit failure states correspond to collapse of a series of structural members which are identified by engineering design criteria. In this paper the following aspects are taken into account: the punching shear and buckling failures in member failure modes for the tubular joints and tubular columns respectively; incremental loading approach for establishment of the safety margin equations of system failure; the algorithm of enumerating significant failure modes for the structural systems and other concepts, such as the false failure mode and the virtual limit state. The final work is devoted to the reliability analysis for a practical jacket platform presently put into operation on the Bohai Sea. The computed results shows that method suggested in this paper is feasible and effective for the evaluation of the system reliability of offshore platforms.展开更多
The opposition between the terms carcasse （carcass）, conceptualized by Auguste Perret, and ossature （frame）, proposed as an alternative by Le Corbusier, gives rise to the exploration of the capital contribution of...The opposition between the terms carcasse （carcass）, conceptualized by Auguste Perret, and ossature （frame）, proposed as an alternative by Le Corbusier, gives rise to the exploration of the capital contribution of the ＂Dom-ino＂ prototype as the basic and in escapable condition for an aesthetic operation. Some issues addressed are： the importance of the question of the structure--which remains implicit in Toward an Architecture--as key to a quest for the specificity of architecture; Le Corbusier＇s troublesome relationship with Perret and the debates between them, which convey two different ways of understanding the potential contributions of concrete to the redefinition of architectural vocabulary; the ＂Dom-ino＂ system considered as a new structural type in the sense ascribed to this category by Violletle Duc; the topic of the abri souverain （sovereign shelter） fit for all programs, which triggered typological invention; the ways in which Le Corbusier plays with Gottfried Semper＇s Urformen and, finally, how this new structural type anchors Le Corbusier＇s radical redefinition of the elements of the discipline, the making of a new grammar.展开更多
The newly proposed mega sub-controlled structure system(MSCSS)and related studies have drawn the attention of civil engineers for practice in improving the performance and enhancing the structural effectiveness of meg...The newly proposed mega sub-controlled structure system(MSCSS)and related studies have drawn the attention of civil engineers for practice in improving the performance and enhancing the structural effectiveness of mega frame structures.However,there is still a need for improvement to its basic structural arrangement.In this project,an advanced,reasonable arrangement of mega sub-controlled structure models,composed of three mega stories with different numbers and arrangements of substructures,are designed to investigate the control performance of the models and obtain the optimal model configuration(model with minimum acceleration and displacement responses)under strong earthquake excitation.In addition,the dynamic parameters that affect the performance effectiveness of the optimal model of MSCSS are studied and discussed.The area of the relative stiffness ratio RD,with different mass ratio MR,within which the acceleration and displacement of the optimal model of MSCSS reaches its optimum(minimum)value is considered as an optimum region.It serves as a useful tool in practical engineering design.The study demonstrates that the proposed MSCSS configuration can efficiently control the displacement and acceleration of high rise buildings.In addition,some analytical guidelines are provided for selecting the control parameters of the structure.展开更多
The study on the dynamic characteristics of light steel residential structural system has both theoretical and practical significance for the application and promotion of light steel residential structural system. In ...The study on the dynamic characteristics of light steel residential structural system has both theoretical and practical significance for the application and promotion of light steel residential structural system. In this paper, we analyze several common types of light steel residential structural system, describe the dynamic characteristics of the light steel residential structural system for an overview on the basis of former related studies, and then summarize the advantages of light steel residential structure system.展开更多
In the urban residential building stock, a major proportion is constituted by low-rise individual buildings. In addition to cost, quality and duration, energy consumed for the project needs to be accounted in the deci...In the urban residential building stock, a major proportion is constituted by low-rise individual buildings. In addition to cost, quality and duration, energy consumed for the project needs to be accounted in the decision making process. Minimizing the cost of construction without compromising on the architectural and structural requirements is the primary objective of the residential buildings of stake-holders, especially the owners. The choice of structural system and the materials used for construction play a crucial role in this effort. This means that the use of expensive and/or voluminous materials such as cement, steel, masonry etc. is optimized. This could lead to significant reduction in embodied energy as well, if the choice of the structural system is prudently made. In this paper, an attempt has been made to quantify the cost and embodied energy benefits for a low-rise residential building by choosing two different structural systems, namely moment resisting framed (MRF) construction system and the partly load-bearing (PLB) system. The influence of choice of materials, contributing to reduction of cost and/or energy is discussed. It is clearly noticed that, when the structural system is re-configured as a PLB system from the existing MRF system there is significant reduction in cost and embodied energy without changing the architectural form.展开更多
This study developed an optimal structural system for the hybrid cable-stayed bridge expected to have a durable lifetime of 200 years and of which major structural members are made of ultra high performance concrete (...This study developed an optimal structural system for the hybrid cable-stayed bridge expected to have a durable lifetime of 200 years and of which major structural members are made of ultra high performance concrete (UHPC) with 200 MPa-class compressive strength. This innovative cable-stayed bridge system makes it possible to reduce each of the construction and maintenance costs by 20% compared to the conventional concrete cable-stayed bridge by improving significantly the weight and durability of the bridge. Therefore, detail design is carried out considering a real 800 m cable-stayed bridge and the optimal structure of the hybrid cable-stayed bridge is proposed and verified.展开更多
Coastal lowlands have large areas of hazard impact and relatively low capacity of prevention to the water related hazards,which have been indicated by the wide_spread flood hazards,high percentages of land with high f...Coastal lowlands have large areas of hazard impact and relatively low capacity of prevention to the water related hazards,which have been indicated by the wide_spread flood hazards,high percentages of land with high flood vulnerability.Increasing population pressure and the shift of resources exploitation from land to sea will force more and more coastal lowlands to be developed in the future,further enhancing the danger of water_related hazards.In this paper,the coastal lowlands in the northern Jiangsu province,China,were selected as a case study.The Interpretation Structural Model (ISM) was employed to analyze the direct and indirect impacts among the elements within the system,and thereby,to identify the causal elements,middle linkages,their expressions,and relations.展开更多
An online method of identification of dynamic characteristics only using measured ambient response of structural dynamic system is widely focused on.The Ibrahim and ARMA (AutoRegressive Moving Average) methods are bas...An online method of identification of dynamic characteristics only using measured ambient response of structural dynamic system is widely focused on.The Ibrahim and ARMA (AutoRegressive Moving Average) methods are basic identification methods.A model on dynamic system suffered by random ambient excitation was researched into, and a subspace decomposition method being different from traditional harmonic retrieval method was introduced.Robustness and effectiveness of this approach on identification of vibration characteristics are demonstrated on numerical experiment.展开更多
The current situation and difficulties of the structural system reliability analysis are mentioned. Then on the basis of Monte Carlo method and computer simulation, a new analysis method reduced expanding load method ...The current situation and difficulties of the structural system reliability analysis are mentioned. Then on the basis of Monte Carlo method and computer simulation, a new analysis method reduced expanding load method (RELM) is presented, which can be used to solve structural reliability problems effectively and conveniently. In this method, the uncertainties of loads, structural material properties and dimensions can be fully considered. If the statistic parameters of stochastic variables are known, by using this method, the probability of failure can be estimated rather accurately. In contrast with traditional approaches,RELM method gives a much better understanding of structural failure frequency and its reliability index β is more meaningful.To illustrate this new idea, a specific example is given.展开更多
This work aims the deterministic dynamic analysis,in the time and frequency domain,of a reinforced concrete floor supported by a pre-cast pile foundation system,when subjected to the excitation produced by a large com...This work aims the deterministic dynamic analysis,in the time and frequency domain,of a reinforced concrete floor supported by a pre-cast pile foundation system,when subjected to the excitation produced by a large compressor installed in an industry for the production of air gases.The concrete slab presents a dimension of 12 m×15 m,required to support a compressor-motor assembly weighting 1,900 kN and positioned at a height of 4m of the investigated concrete floor.In this investigation,two numerical models were developed and the difference between these models is characterized by the discretization of the support points(pre-cast concrete piles).The developed numerical model adopted the usual mesh refinement techniques present in finite element method simulations implemented in the CSi SAP2000 V.17.2.0 software.Based on the developed analysis methodology,the dynamic structural response of the foundation system is evaluated in terms of natural frequencies,vibration modes,displacements,velocities,and accelerations.The maximum values of the dynamic response of the system are compared with the limit values recommended by standards and project recommendations,aiming a careful evaluation,regarding the performance of the structure in terms of excessive vibrations and the economic aspects involved in the design of the foundation system.Finally,the obtained results of the two developed numerical models are compared,as to evaluate if there are benefits in refining the support points modelling.展开更多
文摘In the context of global emission reduction, the low-carbon sustainable development of the construction industry has become an important research content. With the vigorous development of new industrial technologies, the application of prefabrication technology to buildings had become a mainstream. However, the research on the role of prefabricated technology in reducing building carbon emissions was not yet comprehensive, and the research on the relationship between prefabricated structure types and carbon emissions in the construction stage was not yet thorough. Guided by life cycle assessment (LCA), this paper used the scenario analysis method to set different working conditions for five different structural systems, and used SimaPro software to evaluate the carbon emissions of prefabricated buildings in order to clarify the carbon emissions of prefabricated buildings under different structural systems, and explore their impact mechanisms in depth. Finally, take the existing buildings in China as an empirical study, the results showed that: 1) The carbon emissions produced by the four common prefabricated structural systems were almost the same. Different structures had different requirements for the combination of components. The carbon emissions of individual buildings would be superimposed according to the carbon emission characteristics of various individual components to form the final total carbon emissions. 2) When the building structure system requires more combinations of components, the greater the amount of transportation invested in the transportation process, the more carbon emissions would be caused. In the calculation of all individual building construction stages, the carbon emissions generated by tower cranes almost exceed the sum of the carbon emissions of all mobile machinery. 3) Prefabricated shear wall structures and prefabricated frame-shear wall structures require a large amount of hoisting of prefabricated shear walls, so the carbon emissions of their mechanical equipment were also the highest.
基金supported by the Ministry of Sciences and Technology of China(2016YFC0600306-4&2015CB452601)the Geological Survey of China(No.DD20179612&DD20160024-04)。
文摘The offset of geological bodies provides robust evidence of displacement along a fault or ductile shear zone. The amount of displacement along the Xuelongshan–Diancangshan–Ailaoshan structural system, southeastern Tibetan Plateau, is uncertain because of the lack of offset geological markers. This NNW–SSE-trending system is developed in three isolated metamorphic complexes and interjacent nonmetamorphosed rocks. They are expected to record similar post-Eocene strain, although their structural patterns should be distinct. Geological mapping in the area between the Xuelongshan and Diancangshan metamorphic complexes has revealed a small Eocene basin, the Madeng Basin, located to the west of the structural system. The sedimentary and volcanic successions of the Madeng Basin are comparable to those of the Jianchuan Basin, which is located to the east of the structural system. Zircon U–Pb geochronological and bulk geochemical data demonstrate that the volcanic rocks of both basins formed during 37–34 Ma and share the same geochemical features. These data suggest that the Madeng and Jianchuan basins previously constituted a single basin, with the distribution of high-K volcanic rocks in the basins defining an ENE–WSW-trending volcanic belt that shows a limited dextral offset of ≤20 km across the Xuelongshan–Diancangshan–Ailaoshan structural system. Therefore, the northern segment of the structural system records no evidence of large-scale lateral movement/displacement. The results suggest that the Indochina block, which is bounded by the Xuelongshan–Diancangshan–Ailaoshan structural system to the east and the Sagaing Fault to the west, has not extruded southward as a whole but rather has been deformed by pervasive crustal shortening.
基金Projects(51409167,51139001,51179066)supported by the National Natural Science Foundation of ChinaProjects(201401022,201501036)supported by the Ministry of Water Resources Public Welfare Industry Research Special Fund,ChinaProjects(GG201532,GG201546)supported by the Scientific and Technological Research for Water Conservancy,Henan Province,China
文摘The structural system failure probability(SFP) is a valuable tool for evaluating the global safety level of concrete gravity dams.Traditional methods for estimating the failure probabilities are based on defined mathematical descriptions,namely,limit state functions of failure modes.Several problems are to be solved in the use of traditional methods for gravity dams.One is how to define the limit state function really reflecting the mechanical mechanism of the failure mode;another is how to understand the relationship among failure modes and enable the probability of the whole structure to be determined.Performing SFP analysis for a gravity dam system is a challenging task.This work proposes a novel nonlinear finite-element-based SFP analysis method for gravity dams.Firstly,reasonable nonlinear constitutive modes for dam concrete,concrete/rock interface and rock foundation are respectively introduced according to corresponding mechanical mechanisms.Meanwhile the response surface(RS) method is used to model limit state functions of main failure modes through the Monte Carlo(MC) simulation results of the dam-interface-foundation interaction finite element(FE) analysis.Secondly,a numerical SFP method is studied to compute the probabilities of several failure modes efficiently by simple matrix integration operations.Then,the nonlinear FE-based SFP analysis methodology for gravity dams considering correlated failure modes with the additional sensitivity analysis is proposed.Finally,a comprehensive computational platform for interfacing the proposed method with the open source FE code Code Aster is developed via a freely available MATLAB software tool(FERUM).This methodology is demonstrated by a case study of an existing gravity dam analysis,in which the dominant failure modes are identified,and the corresponding performance functions are established.Then,the dam failure probability of the structural system is obtained by the proposed method considering the correlation relationship of main failure modes on the basis of the mechanical mechanism analysis with the MC-FE simulations.
基金National Natural Science Foundation Under Grant No.61074045,60721062the 973 Program 2006CB705400 of China
文摘The problem of robust active vibration control for a class of electro-hydraulic actuated structural systems with time-delay in the control input channel and parameter uncertainties appearing in all the mass, damping and stiffness matrices is investigated in this paper. First, by introducing a linear varying parameter, the nonlinear system is described as a linear parameter varying （LPV） model. Second, based on this LPV model, an LMI-based condition for the system to be asymptotically stabilized is deduced. By solving these LMIs, a parameter-dependent controller is established for the closed- loop system to be stable with a prescribed level of disturbance attenuation. The condition is also extended to the uncertain case. Finally, some numerical simulations demonstrate the satisfying performance of the proposed controller.
文摘Due to the shortage of land in cities and population growth,the significance of high rise buildings has risen.Controlling lateral displacement of structures under different loading such as an earthquake is an important issue for designers.One of the best systems is the diagrid method which is built with diagonal elements with no columns for manufacturing tall buildings.In this study,the effect of the distribution of the tuned mass damper(TMD)on the structural responses of diagrid tall buildings was investigated using a new dynamic method.So,a diagrid structural systems with variable height with TMDs was solved as an example of structure.The reason for the selection of the diagrid system was the formation of a stiffness matrix for the diagonal and angular elements.Therefore,the effect of TMDs distribution on the story drift,base shear and structural behaviour were studied.The obtained outcomes showed that the TMDs distribution does not significantly affect on improving the behaviour of the diagrid structural system during an earthquake.Furthermore,the new dynamic scheme represented in this study has good performance for analyzing different systems.Abbreviation:TMD-tuned mass damper;SATMD-semiactive-tuned mass dampers;MDOF-multiple degrees of freedom;m_(i)-mass of ith story of the building;c_(i)-damping coefficient of the ith story of the building;k_(i)-stiffness of ith story of the building;x_(i)-displacement of the ith story of the building;md-mass of damper;c_(d)-damping coefficient of the damper;k_(d)-stiffness of damper;x_(d)-displacement of TMD;M_(i)-generalized mass of the ith normal mode;C_(i)-generalized damping of the ith normal mode;K_(i)-generalized stiffness of the ith normal mode;K_(i)(t)-generalized load of the ith normal mode;Y_(i)(t)-generalized displacement of the ith normal mode;[M]-matrices of mass;[C]-matrices of damping;{P(t)}-consequence external forces;N_(i)(τ)-interpolation functions;[Ai]-mechanical properties of the structure.
基金National Natural Science Foundation under Grant No.61305019&51365017Jiangxi Provincial Natural Science Foundation under Grant No.GJJ13430&GJJ13385the Natural Science Foundation of Jiangxi University of Science and Technology of China under Grant No.NSFJ2014-K16
文摘The problem of active vibration control for uncertain linear structural systems with control forces input timedelay is investigated in this study.First,the original structural equation is converted to a state-space model by utilizing the matrix transformation.Second,according to the obtained model and a special Lyapunov functional,a sufficient condition is achieved for the closed-loop system to be stable with a prescribed level of disturbance attenuation.Then,in terms of solving these linear matrix inequalities（LMIs）,the state-feed controller is achieved to stabilize the structural system with the performance ‖z‖2<γ‖ω‖2.Third,by introducing the rank-1 vector to describe the system uncertainties,the uncertain system description is obtained,and the stabilizing condition is extended to the uncertain case.Finally,examples are given to show the effectiveness of the proposed methods.
基金National Science and Technology Support Program of China(No.2006BAG04B01)
文摘Sutong Bridge,whose layout is [(100+100+300)+1 088 +(300+100+100)] m,marks the largest span of cable-stayed bridges in the world.The complex natural condition at the bridge site and the strict requirements for resistance of wind and seismic action make it crucial to choose a favorable structural system to assure the function and safety of the bridge.The comparison among several optional structural systems for Sutong Bridge is illustrated.After detailed analysis is carried out for viscous damper and hydraulic buffer,super liquid viscous damper with additional displacement limitation is designed for the first application in bridge engineering.The parameters for the damper is analyzed and studied and the dampers are installed successfully after quality tests.
文摘The paper presents a selected group of tension-strut structural systems designed for the construction of lightweight dome covers of large spans, which can be comparatively easy to assembly and have rises of which can be relatively small. This will allow significant decrease costs of erection and maintenance of objects covered by these roof structures. The proposed systems have been obtained from the results of suitable transformations of a chosen type of double-layer space frame and an appropriate arrangement of tetrahedron modules in the space of each of the newly designed type of the structural system. All these systems are built by means of concentric hoops having their own integral spatial stiffness obtained after an appropriate pre-stressing. Particular hoops can be mounted on the ground level and then one by one will be hoisted to the designed positions where they will be connected by means of special sets of the tension members. Due to these structural features, the assembly process of each system should be relatively simple, fast and not expensive. The whole tension-strut structure has to be connected to the compression perimeter ring and suitably pre-stressed. There are presented visualizations of the proposed systems prepared on the basis of the appropriate numerical models especially defined for each particular structure.
文摘In order to investigate the behavior of buildings and engineering structures during earthquakes, based on the data of seismic observation devices mounted on constructions with typical characteristics, results of investigating the change of mechanical properties of building structural system over time and the results of examination of structural rigidity and safety change over time, depending on the dynamic characteristics of the building, determined by experimental investigations made at intervals are mentioned in this article. In addition, evaluation of earthquake acceleration acting on structures due to earthquake-induced damage characteristics of buildings and engineering constructions which are made earthquake resistant is also included here.
文摘General regular shaped diagrid structures can express diverse shapes because braces are installed along the exterior faces of the structures and the structures have no columns. However, since irregular shaped structures have diverse variables, studies to assess behaviors resulting from various variables are continuously required to supplement the imperfections related to such variables. In the present study, materials elastic modulus and yield strength were selected as variables for strength that would be applied to diagrid structural systems in the form of Twisters among the irregular shaped buildings classified by Vollers and that affect the structural design of these structural systems. The purpose of this study is to conduct sensitivity analysis for axial rotation diagrid structural systems according to changes in brace angles in order to identify the design variables that have relatively larger effects and the tendencies of the sensitivity of the structures according to changes in brace angles and axial rotation angles.
文摘A system reliability estimation method for spatial jacket platforms is developed in this paper. The jacket platform is modeled into three-dimensional assembly of spatial beam and plate elements in Finite Element Method (FEM). The limit failure states correspond to collapse of a series of structural members which are identified by engineering design criteria. In this paper the following aspects are taken into account: the punching shear and buckling failures in member failure modes for the tubular joints and tubular columns respectively; incremental loading approach for establishment of the safety margin equations of system failure; the algorithm of enumerating significant failure modes for the structural systems and other concepts, such as the false failure mode and the virtual limit state. The final work is devoted to the reliability analysis for a practical jacket platform presently put into operation on the Bohai Sea. The computed results shows that method suggested in this paper is feasible and effective for the evaluation of the system reliability of offshore platforms.
文摘The opposition between the terms carcasse （carcass）, conceptualized by Auguste Perret, and ossature （frame）, proposed as an alternative by Le Corbusier, gives rise to the exploration of the capital contribution of the ＂Dom-ino＂ prototype as the basic and in escapable condition for an aesthetic operation. Some issues addressed are： the importance of the question of the structure--which remains implicit in Toward an Architecture--as key to a quest for the specificity of architecture; Le Corbusier＇s troublesome relationship with Perret and the debates between them, which convey two different ways of understanding the potential contributions of concrete to the redefinition of architectural vocabulary; the ＂Dom-ino＂ system considered as a new structural type in the sense ascribed to this category by Violletle Duc; the topic of the abri souverain （sovereign shelter） fit for all programs, which triggered typological invention; the ways in which Le Corbusier plays with Gottfried Semper＇s Urformen and, finally, how this new structural type anchors Le Corbusier＇s radical redefinition of the elements of the discipline, the making of a new grammar.
基金National Natural Science Foundation of China under Grant No.51878274。
文摘The newly proposed mega sub-controlled structure system(MSCSS)and related studies have drawn the attention of civil engineers for practice in improving the performance and enhancing the structural effectiveness of mega frame structures.However,there is still a need for improvement to its basic structural arrangement.In this project,an advanced,reasonable arrangement of mega sub-controlled structure models,composed of three mega stories with different numbers and arrangements of substructures,are designed to investigate the control performance of the models and obtain the optimal model configuration(model with minimum acceleration and displacement responses)under strong earthquake excitation.In addition,the dynamic parameters that affect the performance effectiveness of the optimal model of MSCSS are studied and discussed.The area of the relative stiffness ratio RD,with different mass ratio MR,within which the acceleration and displacement of the optimal model of MSCSS reaches its optimum(minimum)value is considered as an optimum region.It serves as a useful tool in practical engineering design.The study demonstrates that the proposed MSCSS configuration can efficiently control the displacement and acceleration of high rise buildings.In addition,some analytical guidelines are provided for selecting the control parameters of the structure.
文摘The study on the dynamic characteristics of light steel residential structural system has both theoretical and practical significance for the application and promotion of light steel residential structural system. In this paper, we analyze several common types of light steel residential structural system, describe the dynamic characteristics of the light steel residential structural system for an overview on the basis of former related studies, and then summarize the advantages of light steel residential structure system.
文摘In the urban residential building stock, a major proportion is constituted by low-rise individual buildings. In addition to cost, quality and duration, energy consumed for the project needs to be accounted in the decision making process. Minimizing the cost of construction without compromising on the architectural and structural requirements is the primary objective of the residential buildings of stake-holders, especially the owners. The choice of structural system and the materials used for construction play a crucial role in this effort. This means that the use of expensive and/or voluminous materials such as cement, steel, masonry etc. is optimized. This could lead to significant reduction in embodied energy as well, if the choice of the structural system is prudently made. In this paper, an attempt has been made to quantify the cost and embodied energy benefits for a low-rise residential building by choosing two different structural systems, namely moment resisting framed (MRF) construction system and the partly load-bearing (PLB) system. The influence of choice of materials, contributing to reduction of cost and/or energy is discussed. It is clearly noticed that, when the structural system is re-configured as a PLB system from the existing MRF system there is significant reduction in cost and embodied energy without changing the architectural form.
文摘This study developed an optimal structural system for the hybrid cable-stayed bridge expected to have a durable lifetime of 200 years and of which major structural members are made of ultra high performance concrete (UHPC) with 200 MPa-class compressive strength. This innovative cable-stayed bridge system makes it possible to reduce each of the construction and maintenance costs by 20% compared to the conventional concrete cable-stayed bridge by improving significantly the weight and durability of the bridge. Therefore, detail design is carried out considering a real 800 m cable-stayed bridge and the optimal structure of the hybrid cable-stayed bridge is proposed and verified.
文摘Coastal lowlands have large areas of hazard impact and relatively low capacity of prevention to the water related hazards,which have been indicated by the wide_spread flood hazards,high percentages of land with high flood vulnerability.Increasing population pressure and the shift of resources exploitation from land to sea will force more and more coastal lowlands to be developed in the future,further enhancing the danger of water_related hazards.In this paper,the coastal lowlands in the northern Jiangsu province,China,were selected as a case study.The Interpretation Structural Model (ISM) was employed to analyze the direct and indirect impacts among the elements within the system,and thereby,to identify the causal elements,middle linkages,their expressions,and relations.
文摘An online method of identification of dynamic characteristics only using measured ambient response of structural dynamic system is widely focused on.The Ibrahim and ARMA (AutoRegressive Moving Average) methods are basic identification methods.A model on dynamic system suffered by random ambient excitation was researched into, and a subspace decomposition method being different from traditional harmonic retrieval method was introduced.Robustness and effectiveness of this approach on identification of vibration characteristics are demonstrated on numerical experiment.
文摘The current situation and difficulties of the structural system reliability analysis are mentioned. Then on the basis of Monte Carlo method and computer simulation, a new analysis method reduced expanding load method (RELM) is presented, which can be used to solve structural reliability problems effectively and conveniently. In this method, the uncertainties of loads, structural material properties and dimensions can be fully considered. If the statistic parameters of stochastic variables are known, by using this method, the probability of failure can be estimated rather accurately. In contrast with traditional approaches,RELM method gives a much better understanding of structural failure frequency and its reliability index β is more meaningful.To illustrate this new idea, a specific example is given.
文摘This work aims the deterministic dynamic analysis,in the time and frequency domain,of a reinforced concrete floor supported by a pre-cast pile foundation system,when subjected to the excitation produced by a large compressor installed in an industry for the production of air gases.The concrete slab presents a dimension of 12 m×15 m,required to support a compressor-motor assembly weighting 1,900 kN and positioned at a height of 4m of the investigated concrete floor.In this investigation,two numerical models were developed and the difference between these models is characterized by the discretization of the support points(pre-cast concrete piles).The developed numerical model adopted the usual mesh refinement techniques present in finite element method simulations implemented in the CSi SAP2000 V.17.2.0 software.Based on the developed analysis methodology,the dynamic structural response of the foundation system is evaluated in terms of natural frequencies,vibration modes,displacements,velocities,and accelerations.The maximum values of the dynamic response of the system are compared with the limit values recommended by standards and project recommendations,aiming a careful evaluation,regarding the performance of the structure in terms of excessive vibrations and the economic aspects involved in the design of the foundation system.Finally,the obtained results of the two developed numerical models are compared,as to evaluate if there are benefits in refining the support points modelling.
