Accurate estimation of the peak seismic responses of structures is important in earthquake resistant design. The internal force distributions and the seismic responses of structures are quite complex, since ground mot...Accurate estimation of the peak seismic responses of structures is important in earthquake resistant design. The internal force distributions and the seismic responses of structures are quite complex, since ground motions are multidirectional. One key issue is the uncertainty of the incident angle between the directions of ground motion and the reference axes of the structure. Different assumed seismic incidences can result in different peak values within the scope of design spectrum analysis for a given structure and earthquake ground motion record combination. Using time history analysis to determine the maximum structural responses excited by a given earthquake record requires repetitive calculations to determine the critical incident angle. This paper presents a transformation approach for relatively accurate and rapid determination of the maximum peak responses of a linear structure subjected to three-dimensional excitations within all possible seismic incident angles. The responses can be deformations, internal forces, strains and so on. An irregular building structure model is established using SAP2000 program. Several typical earthquake records and an artificial white noise are applied to the structure model to illustrate the variation of the maximum structural responses for different incident angles. Numerical results show that for many structural parameters, the variation can be greater than 100%. This method can be directly applied to time history analysis of structures using existing computer software to determine the peak responses without carrying out the analyses for all possible incident angles. It can also be used to verify and/or modify aseismic designs by using response spectrum analysis.展开更多
Pipelines have been acknowledged as the most reliable, economic and efficient means for the transportation of gas and other commercial fluids such as oil and water. The designation of pipeline system as “lifelines” ...Pipelines have been acknowledged as the most reliable, economic and efficient means for the transportation of gas and other commercial fluids such as oil and water. The designation of pipeline system as “lifelines” signifies that their operation is essential in maintaining the public safety and well being. A pipeline transmission system is a linear system which traverses a large geographical area, and soil conditions thus, is susceptible to a wide variety of hazards. This pa-per is concerned with the dynamic behavior of buried town gas pipelines. A computer model with a finite number of nodes is created to simulate the behavior of the real gas pipeline. The dynamic susceptibility method is applied for twenty mode shapes of this model, which utilizes the stress per velocity method and is an incisive analytical tool for screening the vibration modes of the system. It can be readily identified, which modes, if excited, could potentially cause large dynamic stresses. This paper discusses also two of the piping dynamic analyses, namely the effect of the response spectrum of an earthquake and the time history analysis of a truck crosses the pipeline.展开更多
基金Supported by： U.S. Federal Highway Administration Under Grant No. DTFH61-98-C-00094 U.S. National Science Foundation Under Grant No. CMS-9701471
文摘Accurate estimation of the peak seismic responses of structures is important in earthquake resistant design. The internal force distributions and the seismic responses of structures are quite complex, since ground motions are multidirectional. One key issue is the uncertainty of the incident angle between the directions of ground motion and the reference axes of the structure. Different assumed seismic incidences can result in different peak values within the scope of design spectrum analysis for a given structure and earthquake ground motion record combination. Using time history analysis to determine the maximum structural responses excited by a given earthquake record requires repetitive calculations to determine the critical incident angle. This paper presents a transformation approach for relatively accurate and rapid determination of the maximum peak responses of a linear structure subjected to three-dimensional excitations within all possible seismic incident angles. The responses can be deformations, internal forces, strains and so on. An irregular building structure model is established using SAP2000 program. Several typical earthquake records and an artificial white noise are applied to the structure model to illustrate the variation of the maximum structural responses for different incident angles. Numerical results show that for many structural parameters, the variation can be greater than 100%. This method can be directly applied to time history analysis of structures using existing computer software to determine the peak responses without carrying out the analyses for all possible incident angles. It can also be used to verify and/or modify aseismic designs by using response spectrum analysis.
文摘Pipelines have been acknowledged as the most reliable, economic and efficient means for the transportation of gas and other commercial fluids such as oil and water. The designation of pipeline system as “lifelines” signifies that their operation is essential in maintaining the public safety and well being. A pipeline transmission system is a linear system which traverses a large geographical area, and soil conditions thus, is susceptible to a wide variety of hazards. This pa-per is concerned with the dynamic behavior of buried town gas pipelines. A computer model with a finite number of nodes is created to simulate the behavior of the real gas pipeline. The dynamic susceptibility method is applied for twenty mode shapes of this model, which utilizes the stress per velocity method and is an incisive analytical tool for screening the vibration modes of the system. It can be readily identified, which modes, if excited, could potentially cause large dynamic stresses. This paper discusses also two of the piping dynamic analyses, namely the effect of the response spectrum of an earthquake and the time history analysis of a truck crosses the pipeline.
