建筑结构球形支座设计分析

建筑结构中球形支座与公路桥梁中的球形支座受力形态存在显著差异,往往需要承受很大的水平荷载.针对球形支座在水平力作用下转动灵活性减弱的缺点,对传统球形支座形式提出了改进方法；对各种复杂应力状态下的球形支座进行了设计验算,所采用的实用设计方法可供结构设计人员参考；在同济大学国家重点实验室对球形支座进行了试验.     

冻融条件下公路桥梁板式氯丁橡胶支座受压试验研究

公路桥梁橡胶支座比建筑橡胶支座更容易受到气候的影响,为了研究公路桥梁板式氯丁橡胶支座经过冻融循环后的承载力变化情况,采用标准冻融试验箱对氯丁橡胶支座进行25、50、75、100次的冻融循环处理并进行轴心受压试验,研究其在不同冻融循环次数的承载力、极限抗压强度、竖向刚度、弹性模量等各项性能指标的变化,并与标准试件进行对比分析。结果表明经过冻融循环处理的氯丁橡胶支座更容易发生脆性破坏,且钢板外露、裂缝等破坏现象比标准试件更严重。随着冻融循环次数的增加,冻融程度的加深,氯丁橡胶支座极限承载力、极限抗压强度、抗压弹性模量都逐渐降低;采用最小二乘法得出50 a抗压强度和抗压弹性模量的衰减曲线和衰减公式,其变化趋势基本符合指数函数规律。冻融循环后的公路桥梁板式氯丁橡胶支座的各项力学性能指标显著降低,因此应严格控制公路桥梁板式氯丁橡胶支座的温度适用范围,并建议提高其最低适用温度,在寒冷地区尽量采用天然橡胶支座。     

夹层橡胶隔震支座长期力学性能及耐火性能试验研究

对我国生产的直径３００ｍｍ的夹层橡胶隔震支座（铅芯及非铅芯两种类型）进行了长期力学性能及耐火性能试验研究。首先,研究了隔震支座的基本力学性能。其次,对隔震支座频率、温度、压力、大变形等相关性能进行了试验研究。隔震支座的长期性能研究则针对隔震支座在使用期限６０年后（建筑物的寿命通常定为５０年）的力学性能进行了热老化及徐变试验,结果表明隔震支座在使用期限内其力学性能稳定。最后,对隔震支座进行了耐火性能研究。     

Langjährige Messung von Kraft‐ und Verformungsgrößen in Neotopf‐Gleitlagern einer Spannbetonstraßenbrücke. Brückenlager‐Monitoring

Longterm Measuring of Forces and Displacements in Elastomer Pot Sliding Bearings of a Prestressed Concrete Road Bridge. Monitoring of Bridge Bearings Two bearings of a three span prestressed concrete road bridge over the lake Aa in the City of Münster were equipped with elastomer pot sliding bearings with measuring devices during the erection in 1987/88, that are able to measure the distance between sliding slab and covering slab and the rotation of the covering slab. Moreover there are dynamometers, which measure the compression stress of the silicone oil in the pot under the elastomer. With these measuring devices the load history of the bearings during the time of erection of the bridge was monitored. In the 18 years that the bridge is in operation, the bearings have been monitored with these measuring devices. Following the completion of the bridge and further in intervals of some years the loads and displacements of the bearings were monitored especially during lorries were crossing the bridge. The bearings show only minimal attrition after 18 years in use.     

Inspection,condition evaluation and replacement of elastomeric bearings in road bridges

This paper presents the results of an inspection campaign as well as condition evaluation and replacement of more than 1000 elastomeric bridge bearings under service on the Isfahan state highway bridges constructed before 1990. It is the first comprehensive survey of this kind. The research was accomplished through inspection surveys, analysis of existing bridge maintenance data, condition evaluation and replacement of a significant portion of the inspected bearings and expert interviews. Inspection surveys and analysis of extracted data identified the problems and their causes and the merits and potential improvement of performance of each one of the inspected elastomeric bearings. Replacement of the damaged bearings with new ones was performed based on the results of this stage. The expert interviews investigated the practices of Isfahan and surrounding states regarding the selection of bearing manufacturers, the performance and the quality control of elastomeric bearings.     

Parametric finite element investigation of the critical load capacity of elastomeric strip bearings

Elastomeric bearings are used in non-seismic bridge applications and for seismic isolation of structures. These bearings consist of a number of elastomeric (rubber) layers bonded to intermediate steel shim plates. For seismic isolation, the total thickness of rubber provides a low horizontal stiffness, whereas the close spacing of the intermediate shim plates provides a high vertical stiffness, relative to the horizontal, for a given bonded rubber area and shear modulus. During earthquake ground shaking, large lateral displacements will develop across the isolation interface and the individual bearings. The design of elastomeric bearings for seismic isolation requires that the stability of the individual bearings be demonstrated at the maximum bearing displacement. A component of the stability assessment is the determination of the critical load of the bearing at a given lateral displacement. Currently, the critical load is estimated using an approach whereby a ratio, that of the overlapping area between the top and bottom bearing endplates to the bonded rubber area, is used to reduce the critical load at zero lateral displacement, referred to herein as the overlapping area method. This study verifies the finite element method for predicting critical loads in elastomeric bearings, and uses the finite element method to investigate the dependency of the critical load on the bearing geometry. The results of the parametric study were also used to evaluate the predictive capabilities of the overlapping area procedure.     

Rehabilitation assessment of a steel railway bridge by dynamic field testing

The seven-span steel railway bridge crossing the River Nile near Qanater, Egypt, has been reported to have excessive sway under the current railway traffic loads. A rehabilitation plan has been made previously to preserve and enforce the structural condition of this main bridge. Dynamic testing techniques were used here to evaluate the modal properties of the bridge system at different stages of the repair plan. Ambient vibration measurements together with measurements after the passage of trains were conducted. The dynamic parameters of the bridge were extracted using both the Frequency Domain Decomposition (FDD) and the Eigen Realization Algorithm (ERA) techniques. Comparisons were made to understand the basic behaviour of the bridge and to evaluate the effectiveness of the current repair method. The modification in the stiffness of the bridge due to rehabilitation was evaluated. The current rehabilitation strategy proved effective; as a result of this study, further recommendations are made.     

中国青藏铁路北麓河路基冻土动应变速率试验研究

基于低温动三轴试验,研究中国青藏铁路北麓河路基冻结粉质黏土在轴向分级循环荷载作用下的变形特征。在不同负温、频率、围压、含水率条件下,考察冻土试件轴向残余应变时程曲线,获得轴向动应变速率受动应力幅值影响大,并随应力比增大而增大,随负温降低、频率升高、含水率增大而减小,随围压增加而线性增大的结论;据此,提出采用幂函数拟合应力比、负温、含水率、频率与轴向动应变速率之间关系,并合理解释冻土特有的振融沉陷的成因机理。有利于合理预测青藏铁路等实际工程在交通荷载作用下由冻土动力残余变形而产生的沉降量,并对于进一步研究冻土路基列车行驶振陷问题具有重要意义,且为建立冻土疲劳模型积累基础试验成果。     

新大空间交通建筑的挑战

针对交通建筑的职能和形式发生巨大变化的现状,就公路客运、高速铁路、地下铁和城市轻轨铁路等新型大空间交通建筑的发展作了阐述,并对新型大空间交通建筑实例进行了分析,以促进交通建筑的进一步发展。     

Assessment of existing steel railway bridges

A series of dynamic tests, acceleration measurements, evaluation, finite element model simulations and safety index calculations were performed on existing steel railway bridges giving service on railway network. Dynamic tests were fulfilled by using a special test train on these bridges to obtain the dynamic parameters and these parameters were then used to refine the finite element models of the bridges. Once the models have been updated to represent the actual condition, safety indices were calculated for structural components of the bridges for each proposed loading condition. These safety indices were used to calculate failure probabilities of structural members. As the final step, system reliability of the bridges was evaluated based on proposed system models of the bridges. It is believed that this study will provide a reliable background for proposed heavier axle loads resulting from new freight trains by realizing the current condition of bridge structures.     

外高桥保税物流园大跨拉杆拱壳桥设计

上海外高桥保税物流园区进出口检查桥采用大跨度空间拉杆拱壳结构。就检查桥钢结构的结构选型、计算模型的选取、支座布置、荷载取值及组合、构件的控制内力及位移限制、非线性分析、节点设计等作了详细介绍,可供类似工程参考。     

现有铁路钢桥的评估

对现有铁路钢桥进行一系列的动力试验、加速度测量、评估、有限元模拟和安全指数计算。采用专门列车进行动力试验,并获取动力参数。这些参数还可用于建立桥梁的有限元模型。如果模型能够反映实际工况,就能用于计算每种工况下桥梁结构的安全指数。这些安全指数可用于计算杆件的破坏可能性,因此可采用本模型评估桥梁的可靠性。通过了解现有桥梁结构的实际工况,本研究可为新的货运列车重级荷载研究提供可靠依据。     

Real-time wireless vibration monitoring for operational modal analysis of an integral abutment highway bridge

Remote structural health monitoring systems employing a sensor-based quantitative assessment of in-service demands and structural condition are perceived as the future in long-term bridge management programs. However, the data analysis techniques and, in particular, the technology conceived years ago that are necessary for accurately and efficiently extracting condition assessment measures from highway infrastructure have just recently begun maturation. In this study, a large-scale wireless sensor network is deployed for ambient vibration testing of a single-span integral abutment bridge to derive in-service modal parameters. Dynamic behavior of the structure from ambient and traffic loads was measured with accelerometers for experimental determination of the natural frequencies, damping ratios, and mode shapes of the bridge. Real-time data collection from a 40-channel single network operating with a sampling rate of 128 Hz per sensor was achieved with essentially lossless data transmission. Successful acquisition of high-rate, lossless data on the highway bridge validates the proprietary wireless network protocol within an actual service environment. Operational modal analysis is performed to demonstrate the capabilities of the acquisition hardware with additional correlation of the derived modal parameters to a Finite Element Analysis of a model developed using as-built drawings to check plausibility of the mode shapes. Results from this testing demonstrate that wireless sensor technology has matured to the degree that modal analysis of large civil structures with a distributed network is a currently feasible and a comparable alternative to cable-based measurement approaches.     

临时拉力装置在桥梁支座应急更换中的应用

在连续梁桥中,边墩支座失效会导致桥梁受力体系改变,带来重大的安全隐患。如何在不影响桥面交通的情况下,对失效桥梁支座进行维修或更换应急处理,恢复桥梁的受力状态是桥梁安全维护和加固设计的一个重要课题。本文结合北京市某三跨连续梁桥的边墩支座应急抢险,设计了一种新型支座更换临时拉力装置,在不中断交通的前提下实现支座的更换,且可精确控制桥梁边墩反力,具有安全可靠、安装方便、可重复利用等优点,可为同类桥梁支座应急抢险及支座更换提供参考。     

轴颈温度对弹性可倾瓦推力轴承润滑性能的影响

求出了无限长可倾瓦推力轴承的热弹性流体动力润滑数值解，并详细考查了轴颈温度对轴承性能的影响．结果指出．降低轴颈温度可显著增加轴承的承载量，但不会明显改变摩擦系数．     

不同频率循环荷载下公路路基粗粒填料长期动力特性试验研究

 交通荷载作用频率随着车辆运行速度等因素变化而变化,目前对不同频率荷载下路基长期性能还缺乏一致性认识。为揭示不同频率荷载下路基粗粒土填料长期动力特性,利用GDS大型三轴试验系统对路基填料进行饱和排水循环荷载试验,分析不同应力路径下荷载频率对路基粗粒填料长期动力特性影响规律。试验结果表明,荷载频率增加使路基填料在密实阶段产生更大累积体缩应变而更密实,进而路基动力回弹模量随荷载频率增加显著增加。路基填料轴向累积变形在不同频率循环荷载下也呈现不同发展规律,路基填料密实阶段轴向累积变形在高循环应力比(ζ = 3,5)下随荷载频率增加显著增大,但在低循环应力比(ζ = 1)下,荷载频率对轴向累积变形影响较小;当填料进入变形稳定阶段,荷载频率对轴向累积变形基本无影响。该研究揭示了路基填料层在不同频率荷载下长期动力特性,发现降低路基中循环应力比,可大大减小荷载频率对路基长期动力特性影响,本研究可为准确预测和控制道路工后沉降提供参考。     

Uplift of elastomeric bearings in isolated bridges subjected to longitudinal seismic excitations

Bearings are used to isolate bridge substructures from the lateral forces induced by creep, shrinkage and seismic displacements. They are set in one or two support lines parallel to the transverse axis of the pier cap and are typically anchored to the deck and to the pier cap. This detailing makes them susceptible to possible tensile loading. During an earthquake, the longitudinal displacements of the deck induce rotations to the pier caps about a transverse axis, which in turn cause tensile (uplift) and compressive displacements to the bearings. Tensile displacements of bearings, due to the pier rotations, have not been addressed before and questions about the severity of this uplift effect arise, because tensile loading of bearings is strongly related to elastomer cavitation and ruptures. An extended parametric study revealed that bearing uplift may occur in isolated bridges, while uplift effect is more critical for the bearings on shorter piers. Tensile displacements of bearings were found to be significantly increased when the isolators were eccentrically placed with respect to the axis of the pier and when flexible isolators were used for the isolation of the bridge. The results of this study cannot be generalised as bridge response is strongly case-dependent and the approach has limitations, which are related to the modelling approach and to the fact that emphasis was placed on the longitudinal response of bridges.     

Management system for road bridge structural bearings

Support bearings used in road bridges frequently account for a major part of the maintenance budget of the corresponding bridges. In addition, there are considerable indirect costs and inconveniences resulting from rehabilitation operations and consequent interruption of traffic. This paper presents an innovative management system for support bearings used in road bridges. The system encompasses the development of a classification system of bridge support bearings, their anomalies and possible causes, inspection and diagnosis methods, and maintenance and rehabilitation techniques, linked by appropriately validated correlation matrixes. Based on a set of parameters that define degradation levels, the system allows evaluating each defect in terms of physical and functional deterioration and social impact. Priorities for action can then be set according to the parameter considered most critical: anomaly, bearing, bridge or road section.     

静压支承等效面积的近似计算及误差分析

对液体静压支承等效面积的近似计算进行了详尽的误差分析，提出了一种更为精确的近似计算方法．这种方法有较大的实用价值，它不仅适用于普通液体静压支承，而且也能满足大长径比开式静压支承这类特殊的静压支承工程设计的要求．     

利用地下空间改善铁路客运站交通组织的探讨

国内现有的大型铁路客运站,除个别新建的大型交通枢纽外,多数利用地面广场进行旅客集散、车辆停靠、与公共交通接驳等交通组织。随着城市铁路交通运输的发展,地面空间变得局促和紧张,利用地下空间成为发展和扩建的选择。天津海河东路地道及主广场地下工程是天津站交通枢纽工程的重要组成部分,是一个整合了城市地道、城铁出站集散、公交车站、停车场等功能的综合性地下空间。该工程解决了原天津站站前广场停车、车辆进出站、旅客进出站的矛盾,并改善了天津站及附近海河沿岸城市景观。笔者将通过该工程的介绍探讨如何利用地下空间改善铁路客运站的交通组织方式。