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991.
992.
PAN Shaohua XIAQiyi LIN Shiqing XU Lunhuan
Professor Dept. of Coastal Engineering College of Harbour Waterway Coastal Engineering Hohai University Nanjing P. R. China.
Senior Engineer Dept. of Coastal Engineering College of Harbour Waterway Coastal Engineering Hohai University Nanjing P. R. China.
Senior Engineer Fujian Province Ports Shipping Administration Bureau Fuzhou P. R. China. 《中国海洋工程》1999,(2)
Test studies on the wave pressure on a breakwater pier show that the influence of transmissivewave pressure on the outside wall of the breakwater pier is considerable,when the width of the pier is notvery large.The variations of transmissive wave pressure on the breakwater pier with different widths arecompared and the relationship is obtained between relative transmitting distance b/L and wave pressurereduction factor K,which may be used in the design of similar breakwater piers. 相似文献
993.
总结了6种半主动控制算法,采用黏滞阻尼器,对一座三跨简支梁桥进行了不同地震动输入下的半主动控制地震反应计算分析,比较分析了不同地震动输入和半主动控制算法对简支梁桥地震反应控制效果的影响。结果表明,半主动控制能有效地减小桥梁结构的大部分地震反应,同时可能会放大另外部分地震反应,这与地震动输入密切相关,不同地震动输入下的控制效果各不相同。所提六种半主动控制算法中,算法2、5、6对该简支梁桥地震反应的减震效果相对最好,这与各种算法的阻尼器耗能大小有关。 相似文献
994.
环境温度对桥梁结构动力特性影响的试验研究 总被引:2,自引:0,他引:2
本文以两跨钢-混凝土连续组合梁模型和刚架拱桥的环境振动测试为基础,分析了环境温度变化对桥梁动力特性的影响。结果表明:环境温度变化会引起桥梁动力特性的显著变化,同时温度变化对结构动力特性的影响受到桥梁边界约束条件的很大影响,此类测试和分析对桥梁健康监测与损伤识别具有借鉴意义。 相似文献
995.
飘浮体系斜拉桥纵向抗震计算的单塔模型 总被引:1,自引:0,他引:1
通过全桥模型计算结果与单塔模型计算结果的对比,讨论了集中质量在塔上锚固区处堆聚位置,定义了一个结构动力特性和结构地震反应的修正系数,提出了飘浮体系斜拉桥塔纵桥向地震反应计算的单塔模型。多个工程实例的分析结果表明,采用单塔模型的典型误差在15%左右,精度可以满足工程抗震设计的要求,使桥塔的抗震计算得到简化。 相似文献
996.
装配式预制混凝土框架结构拟动力试验研究 总被引:4,自引:0,他引:4
本文对2个采用橡胶垫螺栓连接梁柱节点的单层两跨的装配式预制混凝土框架结构进行拟动力试验,考察结构的破坏模式,研究结构的强度、刚度、滞回、耗能等抗震性能。试验结果表明:此类装配式预制混凝土框架结构具有较好的抗震性能,当层间位移角达到1/25时,结构仍具有一定的承载能力,采用橡胶垫螺栓连接的梁柱节点抗震性能良好,结构体系破坏模式为柱底弯曲破坏。 相似文献
997.
Structural health monitoring of long-span suspension bridges using wavelet packet analysis 总被引:1,自引:0,他引:1
During the service life of civil engineering structures such as long-span bridges, local damage at key positions may continually accumulate, and may finally result in their sudden failure. One core issue of global vibration-based health monitoring methods is to seek some damage indices that are sensitive to structural damage. This paper proposes an online structural health monitoring method for long-span suspension bridges using wavelet packet transform (WPT). The WPT- based method is based on the energy variations of structural ambient vibration responses decomposed using wavelet packet analysis. The main feature of this method is that the proposed wavelet packet energy spectrum (WPES) has the ability to detect structural damage from ambient vibration tests of a long-span suspension bridge. As an example application, the WPES-based health monitoring system is used on the Runyang Suspension Bridge under daily environmental conditions. The analysis reveals that changes in environmental temperature have a long-term influence on the WPES, while the effect of traffic loadings on the measured WPES of the bridge presents instantaneous changes because of the nonstationary properties of the loadings. The condition indication indices VD reflect the influences of environmental temperature on the dynamic properties of the Runyang Suspension Bridge. The field tests demonstrate that the proposed WPES-based condition indication index VD is a good candidate index for health monitoring of long-span suspension bridges under ambient excitations. 相似文献
998.
A wide variety of near-fault strong ground motion records were collected from various tectonic environments worldwide and were used to study the peak value ratio and response spectrum ratio of the vertical to horizontal component of ground motion, focusing on the effect of earthquake magnitude, site conditions, pulse duration, and statistical component. The results show that both the peak value ratio and response spectrum ratio are larger than the 2/3 value prescribed in existing seismic codes, and the relationship between the vertical and horizontal ground motions is comparatively intricate. In addition, the effect of the near-fault ground motions on bridge performance is analyzed, considering both the material nonlinear characteristics and the P~? effect. 相似文献
999.
1000.
The addition of controllable hardware to structures to mitigate vibration that results from dynamic loads is an emerging area of technological development. The paper describes the results of a research project that was conducted to test a relatively new approach to structural control: an adjustable semi-active hydraulic actuation system that was attached to an in service interstate bridge. The system, which is powered by a 12-volt automative battery, has been tested over a 2- year period. Data indicates that the system reduces truck induced peak stresses by over 50 per cent, and calculations, per NCHRP 299, indicate that the safe life of the structure is increased by approximately 50 yr. The installed cost of the system represents less than 10 per cent of the cost to replace the bridge. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献