Prediction of the combination of failure modes for an arch bridge system

An innovative prediction method for the combination of failure modes of an arch bridge is proposed for its probabilistic risk assessment and is compared with the conventional system reliability analysis method. The suggested method reveals various combinations of failure modes in significantly reduced time and efforts in comparison to the previous permutation method or the conventional system reliability analysis method. Additionally, the suggested method can be used for the verification of the system reliability with more specific predictions of the failure modes.Component reliabilities of girders have been evaluated by using response surfaces of the design variables at the selected critical sections, i.e. the maximum shear and negative moment locations. Response Surface Method (RSM) is successfully applied for the reliability analyses of complex structure with relatively small probability of failure. Previous methods such as Monte Carlo Simulations or First Order Second Moment method cannot easily calculate the derivative terms of implicit limit state functions. Hence, the target bridge system is modeled as a series-connection system for the analysis of its system reliability. The upper and lower bound of the probabilities of failure for the structural system have been evaluated and are compared with the suggested prediction method for all possible combination of failure modes.     

Transverse displacement capacity and stiffness of steel plate girder bridge superstructures for seismic loads

Ductile end cross frames have been shown to reduce the transverse seismic demand in composite steel plate girder bridge superstructures. However, the effectiveness of these cross frames is strongly influenced by the transverse flexibility of the superstructure and its capacity for potentially large relative transverse displacements between the deck slab and bearing supports. A simplified method is developed in this paper for the calculation of these displacements based on the elastic girder stresses and transverse girder stiffnesses, which are shown to compare well with results given by the finite element method. In addition the method is shown to give results that compare well with experimental data from a 0.4 scale model subject to shake table excitation. Parametric studies are then described that show typical I-girder superstructures are able to accommodate large transverse drifts (up to 17% of the girder height) while remaining in the elastic range. These large drifts are possible without distress to the slab-to-girder connection, by omitting shear studs over a short length of the girder at the support cross frame locations. Based on the above, a step-by-step procedure is proposed for evaluating the transverse displacement, stiffness and capacity of the steel girder superstructures in the region of the end and intermediate supports.     

斜拉桥方案及其景观环境适应性探讨--以长沙劳动大桥为例

本文介绍了劳动大桥桥位环境及部分斜拉桥方案，并对部分斜拉桥方案在此特殊位置的景观环境适应性作了初步探讨。     

钢筋混凝土桥墩地震弯剪破坏机理与震后快速修复技术研究

为研究钢筋混凝土桥墩的地震弯剪破坏机理与震后快速修复技术,首先进行了6个圆形截面桥墩试件的拟静力试验,试件均发生严重弯剪破坏,然后利用高流动性早强混凝土和CFRP布对其进行快速修复并在1周内重新进行加载试验,将原桥墩与修复后试件的破坏形态、承载力、延性与耗能能力、刚度退化等进行了对比分析。研究表明:塑性铰区配箍满足我国《公路桥梁抗震设计细则》(JTG/T B02-01—2008)及美国Caltrans规范要求的钢筋混凝土桥墩试件,最终仍有可能因塑性铰区抗剪强度不足发生弯剪破坏。由于初始损伤的存在,震后修复桥墩试件的初始刚度偏低、屈服位移偏大,但极限承载力较原试件均有不同程度的提高,延性与耗能能力达到或超过原试件,刚度可有效恢复至原桥墩试件水平,震后修复试件呈弯曲破坏形态,显示出修复方法的有效性。     

青岛市同三线某桥25mT梁载荷试验及分析

为保证既有桥梁青岛市同三线某预应力T梁桥能够继续正常使用,对其主要受力构件——主梁进行了载荷试验并对试验数据进行了分析,最终得出该桥现阶段能够满足行车要求的结论。     

河曲县禹庙拱桥爆破拆除施工方案

针对旧桥拆除,由于周围有建筑物和住户,常规爆破无法完成的情况,阐述了在确保安全的前提下,成功实施定向控制爆破的施工方案,提出了具体的防护措施及防护原则,积累了拱桥爆破拆除施工经验。     

Relationship between earthquake disturbance,tropical rainstorms and debris movement: an overview from Taiwan

The tectonically active island of Taiwan experiences numerous earthquakes and some four major typhoons each year. The paper considers the development of debris movements, especially those associated with Typhoon Toraji which passed over the island in 2001, 2 years after the M_L 7.3 Chi-Chi earthquake. The ratio of new and reactivated landslides before and after the Chi-Chi earthquake is discussed and an explanation put forward for the movement of very large blocks down the river valleys.     

土木工程专业考查课发散式教学方法探讨与实践——以桥涵水文课程为例

土木工程专业考查课为专业人才培养不可或缺的环节之一,但在教学中并未得到足够重视。对国内具有代表性的10所高校土木工程专业考查课进行了调查,针对其教学弊端,提出发散式教学方法,并以桥涵水文课程为例对该教学方法进行了探讨。实践表明,该方法改变了专业考查课教学方法单一、学生学习被动和课程考核单一的现状,有效实现了教学互动。     

Top management support—almost always necessary and sometimes sufficient for success: Findings from a fuzzy set analysis

This paper builds on the work of Young and Jordan (2008) to provide stronger empirical evidence of the importance of top management support for project success. Fuzzy set analysis of 15 cases showed top management support to be much more necessary than any other success factor and sometimes being sufficient for success. The research adds to the evidence that current practice emphasizing project methodologies may be misdirecting effort.     

Regional growth and spatial spillovers: Evidence from an SpVAR for the Spanish regions

This paper provides a spatial vector autoregressive (SpVAR) analysis of growth spillovers for the Spanish regions over the period 1965–2003. First, a spatial Granger causality analysis is performed that indicates the relevant impact of spatial spillover effects across regions in Spain. Second, the empirical research offers a contribution in the context of the SpVAR modelling estimating the push‐in (from the neighbours to the region) and push‐out (from the region to its neighbours) effects of growth spillovers within a regional economic system. Finally, the proposed methodology reveals empirical evidence about both the short‐run and long‐term regional growth adjustment processes in space and time. The results for the Spanish regional panel data suggest the existence of strong spatiotemporal regional spillovers of growth output. This has important implications for the choice of regional policy goals and regional policy instruments.     

Ammonia volatilization from a paddy field following applications of urea: rice plants are both an absorber and an emitter for atmospheric ammonia

Ammonia (NH(3)) volatilization from a paddy field following applications of urea was measured. Two lysimeters of Gray Lowland soil with a pH (H(2)O) of 5.7 were used for the experiment. Urea was applied at a rate of 50 kg N ha(-1) by incorporation as the basal fertilization (BF) and at rates of 30 and 10 kg N ha(-1) by top-dressing as the first (SF1) and second (SF2) supplemental fertilizations, respectively. Two wind tunnels per lysimeter were installed just after BF; one was transplanted with rice plants (PR plot), and the other was without rice plants (NR plot). Weak volatilization was observed at the PR plots after BF. By contrast, strong volatilization was observed at the PR plots after SF1 with a maximum flux of 150 g N ha(-1) h(-1); however, almost no volatilization was observed after SF2. The NH(3) volatilization loss accounted for 2.1%, 20.9%, 0.5%, and 8.2% of the applied urea at each application, BF, SF1, SF2, and the total application, respectively, for which only the net fluxes as volatilization were accumulated. The NH(3) volatilization fluxes from the paddy water surface (F(vol)) at the NR plots were estimated using a film model for its verification. After confirmation of good correlation, the film model was applied to estimate F(vol) at the PR plots. The NH(3) exchange fluxes by rice plants (F(ric)) were obtained by subtracting F(vol) from the observed net NH(3) flux. The derived F(ric) showed that the rice plants emitted NH(3) remarkably just after SF1 when a relatively high rate of urea was applied, although they absorbed atmospheric NH(3) in the other periods. In conclusion, rice plants are essentially an absorber of atmospheric NH(3); however, they turn into an emitter of NH(3) under excess nutrition of ammoniacal nitrogen.