A new type of airtight wall with the combination of foamed concrete and pier support was designed in this study. Based on the theories and models related to the foamed concrete and blasting shock load, using the numer...A new type of airtight wall with the combination of foamed concrete and pier support was designed in this study. Based on the theories and models related to the foamed concrete and blasting shock load, using the numerical analysis method, this study obtains the new material＇s mechanical and destruction laws through analyzing its reaction to different conditions of load （mining and shock waves）, airtight wall thickness （1.2, 1.5, 1.8, 2.1 m） and steel pipe diameters （400, 450, 500 and 600 mm）. The results show that： ①foamed concrete can have very good suspension, and the pier column support is the main carrier of roof pressure; ② the damaged area of foamed concrete decreases as the foamed concrete thickness increases. Under impact loading, the thickness of the foamed concrete wall plays a more obvious role in retaining its integrity; ③under the same mining pressure, the damage area increases as the steel pipe diameter increases; ④ with additional mining stress increase, under whether static load or impact load, the stress on the foamed concrete and steel pipe will also increase gradually, therefore the actual airtight wall design will need to be based on specific circumstances in steel stress.展开更多
Fibre-reinforced polymer (FRP) composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete (RC) columns. To design FRP jackets safely and economically, the behaviour of such ...Fibre-reinforced polymer (FRP) composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete (RC) columns. To design FRP jackets safely and economically, the behaviour of such columns should be predicted first. This paper is concerned with the analysis and behaviour of FRP-confined RC circular and rectangular short col- umns subjected to eccentric loading. A simple design-oriented stress-strain model for FRP-confined concrete in a section analysis was first proposed. The accuracy was then proved by two test data. Following that, a parametric study including amount of FRP confinement, FRP strain capacity, unconfined concrete strength and shape of column section is provided. Some conclusions were obtained at the end of the paper. The work here will provide a comprehensive understanding of the behaviour of FRP-confined concrete columns. The simplicity of the model also enables a simple equivalent stress block to be developed for direct use in practical design.展开更多
An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concr...An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concrete-filled steel tubular column,the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column.According to the results of the plane detection method and embedded sounding pipe method,the cementing status of steel tube and concrete can be concluded,which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.展开更多
A 4th-order low-pass filter （LPF） based on active-Gm-RC structure for multi-standard system application is presented in this paper. The performances of LPF are controlled by a 1-bit control- voltage, and the cut-off...A 4th-order low-pass filter （LPF） based on active-Gm-RC structure for multi-standard system application is presented in this paper. The performances of LPF are controlled by a 1-bit control- voltage, and the cut-off frequency, channel selectivity, and linearity of the proposed filter can be reconfigured accordingly. In order to improve the accuracy of the cut-off frequency, a binary-weigh- ted switched-capacitor array is employed as the auto-tuning circuits to calibrate the RC-time con- stant. Fabricated in TSMC 0. 18μm RF CMOS process, the proposed LPF achieves a measured cutoff frequency of 1.95 and 12.3MHz for WCDMA and GPS/Galileo application with a bandwidth de viation less than 4%. The measured l dB compression points are -3.0dBm and -5.1 dBm respectively for different modes. The core circuit of LPF consumes l mW and 1.6mW for WCDMA and GPS/Galileo respectively. And the proposed LPF occupies an area of 0.78ram2.展开更多
NLTHA （nonlinear time history analysis） is impractical for widespread used by the professional engineer because it requires long and inefficient computational time involving complexities when six DOF （degree of fre...NLTHA （nonlinear time history analysis） is impractical for widespread used by the professional engineer because it requires long and inefficient computational time involving complexities when six DOF （degree of freedom） per node is applied. The NLTHA nowadays is predicted by MPA （modal pushover analysis）. In this method, effects of higher modes on the dynamic response are considered to estimate seismic demands for structures. In this study, the effect of the reduction of number of DOF is analyzed using 3D NLTHA together with MPA of a rigid connection RC bridge under large earthquake motion. The results are compared with the 6 DOF NLTHA in terms of response of the structure and CPU time to obtain the most efficient computational effort. Result of NLTHA showed that the computational time of the structure both for 4 DOF （without two lateral torsional effects） and 3 DOF （without two lateral torsional and vertical displacements） was reduced significantly compared to the structure using 6 DOF. The reduction of computational time was close to fifty percent both for 4 and 3 DOF＇s. When the maximum responses between NLTHA and MPA are compared, it is found that the differences are insignificant.展开更多
文摘A new type of airtight wall with the combination of foamed concrete and pier support was designed in this study. Based on the theories and models related to the foamed concrete and blasting shock load, using the numerical analysis method, this study obtains the new material＇s mechanical and destruction laws through analyzing its reaction to different conditions of load （mining and shock waves）, airtight wall thickness （1.2, 1.5, 1.8, 2.1 m） and steel pipe diameters （400, 450, 500 and 600 mm）. The results show that： ①foamed concrete can have very good suspension, and the pier column support is the main carrier of roof pressure; ② the damaged area of foamed concrete decreases as the foamed concrete thickness increases. Under impact loading, the thickness of the foamed concrete wall plays a more obvious role in retaining its integrity; ③under the same mining pressure, the damage area increases as the steel pipe diameter increases; ④ with additional mining stress increase, under whether static load or impact load, the stress on the foamed concrete and steel pipe will also increase gradually, therefore the actual airtight wall design will need to be based on specific circumstances in steel stress.
文摘Fibre-reinforced polymer (FRP) composites were widely utilized in civil engineering structures as the retrofit of reinforced concrete (RC) columns. To design FRP jackets safely and economically, the behaviour of such columns should be predicted first. This paper is concerned with the analysis and behaviour of FRP-confined RC circular and rectangular short col- umns subjected to eccentric loading. A simple design-oriented stress-strain model for FRP-confined concrete in a section analysis was first proposed. The accuracy was then proved by two test data. Following that, a parametric study including amount of FRP confinement, FRP strain capacity, unconfined concrete strength and shape of column section is provided. Some conclusions were obtained at the end of the paper. The work here will provide a comprehensive understanding of the behaviour of FRP-confined concrete columns. The simplicity of the model also enables a simple equivalent stress block to be developed for direct use in practical design.
文摘An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concrete-filled steel tubular column,the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column.According to the results of the plane detection method and embedded sounding pipe method,the cementing status of steel tube and concrete can be concluded,which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.
基金Supported by the National Basic Research Program of China(No.2010CB327404)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A 4th-order low-pass filter （LPF） based on active-Gm-RC structure for multi-standard system application is presented in this paper. The performances of LPF are controlled by a 1-bit control- voltage, and the cut-off frequency, channel selectivity, and linearity of the proposed filter can be reconfigured accordingly. In order to improve the accuracy of the cut-off frequency, a binary-weigh- ted switched-capacitor array is employed as the auto-tuning circuits to calibrate the RC-time con- stant. Fabricated in TSMC 0. 18μm RF CMOS process, the proposed LPF achieves a measured cutoff frequency of 1.95 and 12.3MHz for WCDMA and GPS/Galileo application with a bandwidth de viation less than 4%. The measured l dB compression points are -3.0dBm and -5.1 dBm respectively for different modes. The core circuit of LPF consumes l mW and 1.6mW for WCDMA and GPS/Galileo respectively. And the proposed LPF occupies an area of 0.78ram2.
文摘NLTHA （nonlinear time history analysis） is impractical for widespread used by the professional engineer because it requires long and inefficient computational time involving complexities when six DOF （degree of freedom） per node is applied. The NLTHA nowadays is predicted by MPA （modal pushover analysis）. In this method, effects of higher modes on the dynamic response are considered to estimate seismic demands for structures. In this study, the effect of the reduction of number of DOF is analyzed using 3D NLTHA together with MPA of a rigid connection RC bridge under large earthquake motion. The results are compared with the 6 DOF NLTHA in terms of response of the structure and CPU time to obtain the most efficient computational effort. Result of NLTHA showed that the computational time of the structure both for 4 DOF （without two lateral torsional effects） and 3 DOF （without two lateral torsional and vertical displacements） was reduced significantly compared to the structure using 6 DOF. The reduction of computational time was close to fifty percent both for 4 and 3 DOF＇s. When the maximum responses between NLTHA and MPA are compared, it is found that the differences are insignificant.
