In recent years, precast segmental concrete bridge columns became prevalent because of the benefits of accelerated construction, low environmental impact, high quality and low life cycle costs. The lack of a detailed ...In recent years, precast segmental concrete bridge columns became prevalent because of the benefits of accelerated construction, low environmental impact, high quality and low life cycle costs. The lack of a detailed configuration and appropriate design procedure to ensure a comparable performance with monolithic construction has impeded this structural system from being widely used in areas of high seismicity. In this study, precast segmental bridge column cyclic loading tests were conducted to investigate the performance of unbonded post-tensioned segmental bridge columns. One monolithic and two precast segmental columns were tested. The preeast segmental column exhibited minor damage and small residual displacement after the maximum 7% cyclic drift; energy dissipation （ED） can be enhanced byadding ED bars. The experimental results were modeled by a simplified pushover method （SPOM）, as well as a fiber model （FIBM） finite element method. Forty-five cases of columns with different aspect ratios, axial load ratios and ED bar ratios were analyzed with the SPOM and FIBM, respectively. Using these parametric results, a simplified design method was suggested by regressive analysis. Satisfactory correlation was found between the experimental results and the simplified design method for preeast segmental columns with different design parameters.展开更多
Based on the Biot’s wave equation and theory of thermodynamic, Darcy law of fluid and the modified Fourier law of heat conduction, a nonlinear fully coupled thermo-hydro-elastodynamic response model (THMD) for satura...Based on the Biot’s wave equation and theory of thermodynamic, Darcy law of fluid and the modified Fourier law of heat conduction, a nonlinear fully coupled thermo-hydro-elastodynamic response model (THMD) for saturated porous medium is derived. The compressibility of the medium, the influence of fluid flux on the heat flux, and the influence of change of temperature on the fluid flux are considered in this model. With some simplification, the coupled nonlinear thermo-hydro-elastodynamic response model can be reduced to the thermo-elastodynamic (TMD) model based on the traditional Fourier law and, further more, to the Biot’s wave equation without considering the heat phase. At last, the problem of one dimensional cylindrical cavity subjected to a time-dependent thermal/mechanical shock is analyzed by using the Laplace technique, the numerical results are used to discuss the influence of Biot’s modulus M and coefficient of thermoos-mosis on displacement and to compare with the results of thermo-elastodynamic response to ascertain the validity of this model.展开更多
基金National Natural Science Foundation of China under Grants Nos.51208268 and 51178429K.C.Wong Magna Fund in Ningbo University+1 种基金Transportation Science and Technology Project of Ningbo City under Grant No.201507Natural Science Foundation of Ningbo City under Grant No.2015A610293
文摘In recent years, precast segmental concrete bridge columns became prevalent because of the benefits of accelerated construction, low environmental impact, high quality and low life cycle costs. The lack of a detailed configuration and appropriate design procedure to ensure a comparable performance with monolithic construction has impeded this structural system from being widely used in areas of high seismicity. In this study, precast segmental bridge column cyclic loading tests were conducted to investigate the performance of unbonded post-tensioned segmental bridge columns. One monolithic and two precast segmental columns were tested. The preeast segmental column exhibited minor damage and small residual displacement after the maximum 7% cyclic drift; energy dissipation （ED） can be enhanced byadding ED bars. The experimental results were modeled by a simplified pushover method （SPOM）, as well as a fiber model （FIBM） finite element method. Forty-five cases of columns with different aspect ratios, axial load ratios and ED bar ratios were analyzed with the SPOM and FIBM, respectively. Using these parametric results, a simplified design method was suggested by regressive analysis. Satisfactory correlation was found between the experimental results and the simplified design method for preeast segmental columns with different design parameters.
基金Supported by the National Natural Science Foundation of China (Grant No. 50679074) ZJ(NB)NSF (Grant Nos. Y107637, 2007A6100626)
文摘Based on the Biot’s wave equation and theory of thermodynamic, Darcy law of fluid and the modified Fourier law of heat conduction, a nonlinear fully coupled thermo-hydro-elastodynamic response model (THMD) for saturated porous medium is derived. The compressibility of the medium, the influence of fluid flux on the heat flux, and the influence of change of temperature on the fluid flux are considered in this model. With some simplification, the coupled nonlinear thermo-hydro-elastodynamic response model can be reduced to the thermo-elastodynamic (TMD) model based on the traditional Fourier law and, further more, to the Biot’s wave equation without considering the heat phase. At last, the problem of one dimensional cylindrical cavity subjected to a time-dependent thermal/mechanical shock is analyzed by using the Laplace technique, the numerical results are used to discuss the influence of Biot’s modulus M and coefficient of thermoos-mosis on displacement and to compare with the results of thermo-elastodynamic response to ascertain the validity of this model.
