The nonlinear behavior of a soil-foundation system may alter the seismic response of a structure by providing additional flexibility to the system and dissipating hysteretic energy at the soil-foundation interface. Ho...The nonlinear behavior of a soil-foundation system may alter the seismic response of a structure by providing additional flexibility to the system and dissipating hysteretic energy at the soil-foundation interface. However, the current design practice is still reluctant to consider the nonlinearity of the soil-foundation system, primarily due to lack of reliable modeling techniques. This study is motivated towards evaluating the effect of nonlinear soil-structure interaction （SSI） on the seismic responses of low-rise steel moment resisting frame （SMRF） structures. In order to achieve this, a Winkler- based approach is adopted, where the soil beneath the foundation is assumed to be a system of closely-spaced, independent, nonlinear spring elements. Static pushover analysis and nonlinear dynamic analyses are performed on a 3-story SMRF building and the performance of the structure is evaluated through a variety of force and displacement demand parameters. It is observed that incorporation of nonlinear SSI leads to an increase in story displacement demand and a significant reduction in base moment, base shear and inter-story drift demands, indicating the importance of its consideration towards achieving an economic, yet safe seismic design.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
In this paper,a computational approach is undertaken to determine the rotational stiffness and moment capacity provided by typical“pinned”column base-plate connections in low-rise metal buildings by analyzing a wide...In this paper,a computational approach is undertaken to determine the rotational stiffness and moment capacity provided by typical“pinned”column base-plate connections in low-rise metal buildings by analyzing a widerange of connection parameters.The most influencing details of the connections on the overall behavior were identified.First,development and validation of high-fidelity computational models using experimental data are described.Then,the validated models were used to perform a parametric study to understand the effect of configurational details on the rotational stiffness and moment capacity of the column base-plate connections with anchor rods between the flanges.Anchor rod diameter,by itself,and in combination with base-plate thickness,was found to be the most influential parameter on the moment capacity of connections with smaller web depths.For larger web depths,the number of anchor rods was influential in the moment capacity,particularly,in one of the loading directions.展开更多
Gable roofs with overhangs （eaves） are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gabl...Gable roofs with overhangs （eaves） are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative （block） pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future＇s modification of wind load codes.展开更多
This study presents a development of an advanced cyberbased database-enabled design module for low- rise buildings （DEDM-LR） which provides estimation of the wind-induced responses for main wind force resisting fram...This study presents a development of an advanced cyberbased database-enabled design module for low- rise buildings （DEDM-LR） which provides estimation of the wind-induced responses for main wind force resisting frames by making direct use of pressure time histories measured at a large number of pressure taps over a suite of building models. These responses may be considered in lieu of code-specified load effects in which the overall accuracy may be influenced by the inherent simplifications in codes. In addition, this new automated approach is particularly attractive and advantageous as it allows a web-based online analysis/design via intuitive user-friendly interfaces for both the input and output in terms of familiar web-style forms that are nowadays very common in most of web-based services. Presently, the DEDM-LR hosts an aerodynamic database developed by the Tokyo Polytechnic University （TPU）, Japan for a variety of building configurations like flat, gable, and hip roofs under suburban terrain flow condition with immediate application to other databases. The paper shows the efficacy and validity of the DEDM-LR by walking through its details and examples on selected gable-roofed buildings. The architecture of DEDM-LR platform offers the ability to pool resources by hosting other databases that may become available in the near future.展开更多
This paper presents an extensive review of existing techniques used in estimating design wind pressures considering Reynolds number and turbulence effects,as well as a case study of a reference building investigated e...This paper presents an extensive review of existing techniques used in estimating design wind pressures considering Reynolds number and turbulence effects,as well as a case study of a reference building investigated experimentally.We shed light on the limitations of current aerodynamic testing techniques,provisions in design standards,and computational fluid dynamics(CFD)methods to predict wind-induced pressures.The paper highlights the reasons for obstructing the standardization of the wind tunnel method.Moreover,we introduce improved experimental and CFD techniques to tackle the identified challenges.CFD provides superior and efficient performance by employing wall-modeled large-eddy simulation(WMLES)and hybrid RANS-LES models.In addition,we tested a large-scale building model and compared the results with published small-scale data.The findings reinforce our hypothesis concerning the scaling issues and Reynolds number effects in aerodynamic testing.展开更多
文摘The nonlinear behavior of a soil-foundation system may alter the seismic response of a structure by providing additional flexibility to the system and dissipating hysteretic energy at the soil-foundation interface. However, the current design practice is still reluctant to consider the nonlinearity of the soil-foundation system, primarily due to lack of reliable modeling techniques. This study is motivated towards evaluating the effect of nonlinear soil-structure interaction （SSI） on the seismic responses of low-rise steel moment resisting frame （SMRF） structures. In order to achieve this, a Winkler- based approach is adopted, where the soil beneath the foundation is assumed to be a system of closely-spaced, independent, nonlinear spring elements. Static pushover analysis and nonlinear dynamic analyses are performed on a 3-story SMRF building and the performance of the structure is evaluated through a variety of force and displacement demand parameters. It is observed that incorporation of nonlinear SSI leads to an increase in story displacement demand and a significant reduction in base moment, base shear and inter-story drift demands, indicating the importance of its consideration towards achieving an economic, yet safe seismic design.
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In this paper,a computational approach is undertaken to determine the rotational stiffness and moment capacity provided by typical“pinned”column base-plate connections in low-rise metal buildings by analyzing a widerange of connection parameters.The most influencing details of the connections on the overall behavior were identified.First,development and validation of high-fidelity computational models using experimental data are described.Then,the validated models were used to perform a parametric study to understand the effect of configurational details on the rotational stiffness and moment capacity of the column base-plate connections with anchor rods between the flanges.Anchor rod diameter,by itself,and in combination with base-plate thickness,was found to be the most influential parameter on the moment capacity of connections with smaller web depths.For larger web depths,the number of anchor rods was influential in the moment capacity,particularly,in one of the loading directions.
文摘Gable roofs with overhangs （eaves） are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative （block） pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future＇s modification of wind load codes.
文摘This study presents a development of an advanced cyberbased database-enabled design module for low- rise buildings （DEDM-LR） which provides estimation of the wind-induced responses for main wind force resisting frames by making direct use of pressure time histories measured at a large number of pressure taps over a suite of building models. These responses may be considered in lieu of code-specified load effects in which the overall accuracy may be influenced by the inherent simplifications in codes. In addition, this new automated approach is particularly attractive and advantageous as it allows a web-based online analysis/design via intuitive user-friendly interfaces for both the input and output in terms of familiar web-style forms that are nowadays very common in most of web-based services. Presently, the DEDM-LR hosts an aerodynamic database developed by the Tokyo Polytechnic University （TPU）, Japan for a variety of building configurations like flat, gable, and hip roofs under suburban terrain flow condition with immediate application to other databases. The paper shows the efficacy and validity of the DEDM-LR by walking through its details and examples on selected gable-roofed buildings. The architecture of DEDM-LR platform offers the ability to pool resources by hosting other databases that may become available in the near future.
基金The second author(A.M.Aly)received financial support from the Louisiana Board of Regents(RCS,LEQSF(2021-22)-RD-A-30)Also,the second author received funds from the NSF I-Corps program at Louisiana State University.The findings are those of the authors and do not necessarily reflect the position of the funding sponsors.
文摘This paper presents an extensive review of existing techniques used in estimating design wind pressures considering Reynolds number and turbulence effects,as well as a case study of a reference building investigated experimentally.We shed light on the limitations of current aerodynamic testing techniques,provisions in design standards,and computational fluid dynamics(CFD)methods to predict wind-induced pressures.The paper highlights the reasons for obstructing the standardization of the wind tunnel method.Moreover,we introduce improved experimental and CFD techniques to tackle the identified challenges.CFD provides superior and efficient performance by employing wall-modeled large-eddy simulation(WMLES)and hybrid RANS-LES models.In addition,we tested a large-scale building model and compared the results with published small-scale data.The findings reinforce our hypothesis concerning the scaling issues and Reynolds number effects in aerodynamic testing.
