Ductility Evaluation of Concrete-Encased Steel Bridge Piers Subjected to Lateral Cyclic Loading

An experimental and analytical study was conducted to investigate the ductility of concrete-encased steel piers, referred to as “steel-reinforced concrete (SRC) construction.” Based on the cyclic lateral loading tests of SRC column specimens, the restorable and ultimate limit states are defined as the point when concrete cover spalling occurs (equivalent to longitudinal bar buckling) and the point when flange buckling of the H-shaped steel occurs, respectively. To estimate the lateral displacement capacity at both the restorable and ultimate limit states, the curvature distribution of the column was calculated based on the buckling analysis of the longitudinal bar, which was restrained by a concrete cover and transverse reinforcement, and of the steel flange encased in concrete. The lateral displacement was obtained by integrating the curvature distribution. Comparison of the computed results with experimental results, including other writers’ reports, confirmed that the proposed method can appropriately estimate the lateral displacement at the restorable and ultimate limit states, and it can accurately evaluate the buckling characteristics of the longitudinal bar and steel flange components of SRC column specimens.     

Experimental Dynamic Response of a Short-Span Composite Bridge to Military Vehicles

A continued desire for increased mobility in the aftermath of natural disasters or on the battlefield has lead to the need for improved lightweight bridging solutions. Currently, within the U.S. military, there is a need for a lightweight bridging system for crossing short-span gaps up to 4 m (13.1 ft) in length. This paper describes the field testing of a newly developed lightweight fiber-reinforced polymer bridging system to meet the U.S. militaries needs. The study investigates dynamic impact loads of track and wheel vehicles at different crossing speeds to increase understanding of appropriate impact factors used in design. It was found that the impact loads for the bridge treadways were most sensitive to vehicle crossing speed and vehicle type (wheel versus track and axle spacing) with observed impact factors as high as 1.71.     

通信机房楼面等效均布活荷载计算及相关问题探讨

简要介绍了通信机房等效活荷载的一般计算方法,对采用有限元法确定井字梁、双向板楼面等效均布活荷载进行了探索研究,并就计算中相关问题进行了探讨,提出了一些观点.     

FPSO系泊系统载荷计算与分析——基于南海"奋进号"FPSO运动特性实船测量结果

通过实船测量获得了"天鹅"和"彩虹"台风过境过程中南海"奋进号"FPSO运动响应数据.根据实船测量数据,对业界普遍采用的FPSO水动力性能分析数值模型进行了修正.利用修正后的模型,将实船测量获得的船体运动响应数据作为输入项,采用非耦合数值分析技术对南海"奋进号"FPSO系泊系统在实际海况下的载荷进行了计算,并对其在恶劣...     

齐家—鸳鸯沟地区沙河街组油气富集规律研究

针对油气勘探中存在的油水关系复杂问题,采用油气藏解剖和油气分布与成藏条件之间的空间匹配关系,对齐家—鸳鸯沟地区沙河街组油气富集规律及控制因素进行了研究,结果表明:齐家—鸳鸯沟地区油气在纵向上主要分布在沙二段,平面上主要分布在Ⅲ号台阶上,并以断层-岩性油气藏类型居多;油气富集主要受到砂体储层是否发育、圈闭是否发育、断层侧向封闭性强弱、断裂后期活动性强弱4个因素的控制;不同层段油气富集的主控因素不同,沙二段、沙三1亚段和沙四段圈闭不发育是造成失利井的最主要原因,而沙三2亚段和沙三3亚段砂体储层不发育也是造成失利井的最主要原因。     

一种消除AFM中悬臂梁横向扭转串扰误差的修正技术

串扰效应始终存在于原子力显微镜(AFM)的测量过程中,并影响其测量精度.在对串扰效应的产生机理进行分析,并建立了悬臂梁形变与光斑位置检测器(PSPD)输出信号之间的数学关系的基础上,提出了一种可消除横向扭转串扰影响的修正方法.在该方法中AFM系统可由输出信号直接获得悬臂梁的实际形变量,进而获得原子间作用力的实际值,并通过保持作用力的恒定对样品进行测量.该方法可有效地将悬臂梁扭转导致的纵向信号的变化从系统测得的纵向信号中剔除出去.仿真结果表明,在恒力接触模式下,串扰效应严重影响测量结果,导致测量误差,且针尖.样品夹角导致的串扰效应比摩擦力导致的串扰效应更严重.为验证本文方法消除串扰效应的效果,在应用该修正方法前后分别对标准梯形样品进行测量.实验对比结果表明,在普通恒力接触模式下的样品表面最大测量误差范围为21.2 nm～32.0 nm;对串扰效应进行修正后,最大测量误差范围降低至5.5 nm～10.2 nm.这表明该方法可有效降低AFM中串扰效应导致的测量误差,提高其测量精度.     

缓冲器在钢包车上的应用

介绍了缓冲器在钢包车上的应用及效果.炼钢生产中,钢包车是运输钢水的重要设备.但钢包车的使用工况存在较大的冲击载荷,常出现车轮轴断裂、联轴器断齿及车体开焊等故障.钢包车在使用过程中的故障率较高.针对这一状况,提出了在钢包车罐架部位及端梁部位设置不同类型的缓冲器来减小冲击载荷,从而消除因冲击载荷对钢包车设备造成的危害,使钢...     

Anti slip security assessment between main cable and saddle of the middle pylon under extreme vehicle loads

The traffic condition of Taizhou Yangtze River Bridge is obtained to a certain extent, according to the traffic investigation nearby Taizhou Bridge. The statistical characteristics of the traffic conditions are acquired by statistical analysis. Simulation of the extreme vehicle loads and the sensitive analysis of load parameters are carried out based on these data complemented, which would guide the determination of the frictional coefficient between the main cables and the saddle.     

Special Lateral Increase in a Permian Rugose Coral Kepingophyllum aksuence Wu et Chow

Well-preserved specimens of Kepingophyllum aksuence Wu et Chow were collected from Early Permian strata in western Tarim Basin, Xinjiang. More than 100 serial thin sections were made for this study. Kepingophyllum aksuence displays a unique increase pattern. The bud appears in lonsdaleoid dissepiments between the corallites where the wall of parent corallite disappears and the area becomes aphroid. This increase pattern is different from other lateral increases of most colonial rngose corals, and therefore has taxonomic significance to differentiate Kepingophyllidae from other compound rugose corals. It is also discussed that Kepingophyllum aksuence has a high "reproductive integration", which means a rapid growth of buds during the offsetting process. Kepingophyllum was possibly originated from Ivanovia and was also a probable ancestor of Wentzellophyllum, which is supported here by more or less the similarity of the blastogeny in different stages of three taxa.     

Seismic Behavior of As-Built, ACI-Complying, and CFRP-Repaired Exterior RC Beam-Column Joints

In this paper, the efficiency and effectiveness of carbon-fiber-reinforced polymer (CFRP) sheets for upgrading the shear strength and ductility of a seismically deficient exterior beam-column joint were studied and compared with an American Concrete Institute (ACI)-based design joint specimen. One as-built joint specimen, representing the preseismic code design and construction practice for joints and one ACI-based design joint specimen, satisfying the seismic design requirements of the current code of practice were cast. The as-built specimen was used as baseline (control) specimen. These two specimens (i.e., the as-built control and the ACI-based specimens) were subjected to cyclic lateral load histories to induce damage equivalent to damage expected from a severe earthquake. The damaged control specimen was then repaired by filling its cracks with epoxy and externally bonding CFRP sheets to the joint, the beam, and part of the column regions. This specimen was identified as the repaired specimen. The repaired specimen was subjected to a similar cyclic lateral load history, and its response history was recorded. The response histories of the as-built control, the repaired, and the ACI-based design specimen were then compared. The test results demonstrated that externally bonded CFRP sheets can effectively improve both the shear strength and the deformation capacity of seismically deficient and damaged beam-column joints to a state comparable to the ACI-based design joint.