岩石基复合材料支护采空区动力失稳声发射特征统计分析

基于声发射智能监测技术 ,对玲珑金矿 2 5 5m水平坚硬岩石复合材料支护的主运巷采空区结构失稳过程进行了实时监测 ,利用固体断裂非平衡统计理论进行统计推断 ,分析采空区围岩断裂失稳过程中微破裂的时空演化规律以及变形与声发射间的内在联系 ,同时在统计分析过程中考虑了不同因素对围岩破裂过程与失稳模式的影响 ,这对于工程安全监测与评价有很大的现实意义。     

钢结构的隐患及应对措施

影响钢结构安全的因素很多,其中钢结构的稳定问题、钢材锈蚀以及钢结构耐火性差等问题成为影响安全的主要因素。本文论述了钢结构失稳的原因,重点探讨了在设计中如何采用科学的设计理念避免失稳,介绍了钢结构防腐的各项技术措施以及结构抗火设计理念和具体的防火措施。     

山岭隧道围岩失稳的预测研究

结合大丘林2号隧道施工过程,通过长距离的TSP探测和短距离的地质雷达探测,预报前方围岩的地质条件和失稳的可能性,通过对拱顶沉降、围岩收敛、钢拱架内力和围岩压力的监测,有效的预报围岩失稳灾害的发生,其成功的经验可为类似工程提供参考.     

地下大跨度采场围岩突变失稳风险预测

提出了大跨度采场围岩突变失稳的两种形式 :构造控制型失稳和能量控制型失稳。对前者 ,提出了基于块体理论的可靠度分析理论和系统突变失稳预测方法 ;对后者 ,以突变论为理论依据 ,利用有限元分析与可靠度分析中的响应面方法相结合 ,建立了围岩突变失稳预测的可靠度分析方法。提出的预测方法应用于西石门铁矿采场失稳预测 ,获得较满意的结果     

单层球面网壳失稳区域的平衡扰动

在非线性分析的基础上,基于单层网壳结构的失稳机理,对临界点时的失稳区域进行平衡扰动。具体利用奇异值分解法对失稳区域进行几何稳定性判定,并得到相应可能发生的机构位移模态,根据最小势能原理求出失稳后的几何形态,使其进入后屈曲平衡路径。本文的方法是基于网壳结构失稳时的不稳定运动进行的,较为合理地反映了结构失稳的过程,对网壳结构稳定分析方法的进一步研究具有重要意义。     

巷道围岩失稳类型及失稳机理分析

巷道开挖后围岩应力重分布,极易发生失稳破坏。为保证井下生产安全、提高劳动生产效率,本文从工程的观点出发,基于巷道围岩失稳类型分析了影响围岩稳定性的主要因素,通过对巷道围岩应力的弹塑性分析推导出巷道开挖后围岩塑性区半径的表达式,并分析了各因素对塑性区范围的影响趋势和程度,为巷道支护设计提供参考。     

单层球面网壳失稳区域的实用研究

在非线性分析的基础上,基于单层网壳结构的失稳机理,根据作者提出的失稳区域跟踪与判别方法,研究了两种不同形式的单层网壳在不同矢跨比时失稳区域的分布规律,以及失稳之前的弹性变形与失稳区域之间的关系。本文的结论对于网壳结构的稳定性能研究和应用有实际意义。     

煤样失稳破坏的多参量监测试验

 为有效提取由于巷道掘进及工作面回采扰动所诱发的煤岩体剧烈失稳破坏的前兆信息,针对煤样在外载荷作用下失稳破坏前会伴随弹性波、电荷、温度等信号的异常变化的特性,进行包括运用声发射仪、LCR电桥、红外热像仪及静态应变仪等设备在内的监测设备对煤样在单轴加载下的失稳破坏过程进行同步监测;通过建立同一时间坐标轴对多参量监测数据进行对比分析,研究试样失稳破坏前各参量的演化规律;运用多元统计分析中的主成分分析及因子分析方法对多参量监测数据进行分析,发现声发射监测结果能较好地体现出试样破坏的前兆特征,并与应力结果相结合分析可以更好地掌握其失稳破坏的前兆信息。     

透明黏土盾构隧道开挖面失稳扩展过程和失稳特征研究

基于透明黏土盾构隧道开挖面失稳模型试验,探究开挖面失稳扩展过程和失稳特征。在验证透明黏土可用于盾构隧道开挖面失稳破坏试验研究的基础上,从土体运动的角度分析不同埋深比条件下开挖面失稳演化过程,研究失稳分阶段、分区和形态特征以及地表沉降变化规律。基于土体运动的变化,提出盾构开挖面失稳过程实质是开挖面正前方松动土体带动上方土体向隧道内部同步运动,伴随着周围土体受扰动产生运动,并不断扩展变化,最终土体快速滑移发生整体失稳。开挖面失稳呈现明显的分区特征,影响区域包括整体滑移形成的失稳区和产生明显位移形成的扰动区,并提出失稳区的确定标准。开挖面失稳滑移时,纵截面处失稳区土体向隧道内部“流动”,横截面处失稳区呈椭圆状形态。利用对数螺旋线模型和Torus模型对黏土体失稳形态进行描述时,模型底部拟合很好,上部的偏差均较大。开挖面整体失稳前的横截面地表沉降符合高斯沉降曲线,整体失稳后与高斯沉降曲线偏差较大。     

钢结构稳定问题分析浅议

介绍了钢结构失稳的三种不同类型：平衡分岔失稳、极值点失稳、跨越失稳,结合影响钢结构稳定计算的相关因素,探讨了稳定与强度的区别,并阐述了钢结构稳定问题分析原则和特点,以期指导实践。     

钢结构健康监测技术的发展和研究

介绍了钢结构健康监测中的若干新技术和新方法,提出了有待研究的若干理论问题。分析了索杆拉力测试方法的类型、适用范围和优缺点,介绍了钢结构裂缝传感器技术和钢结构支座位移监测和报警技术;总结了结构模态参数识别的理论方法以及基于可靠度理论和模糊数学的既有结构状态评估理论方法;介绍了结构健康监测系统集成管理软件的研发、功能和应用。     

Fatigue stress monitoring and analyses for steel box girder of Runyang Suspension Bridge

The monitoring of fatigue stress of steel bridge is a key issue of bridge health monitoring and safety assessment. This paper aims to find out the strain history features of the girder components of Runyang Suspension Bridge (RYSB) under vehicle and environmental loading during its first year of service based on the strain-history data recorded by structural health monitoring system installed in the bridge. The fatigue stress spectrums of steel box girders under normal traffic load, heavy trucks and typhoon loads were studied as well as the correlation between varying strain and temperature based on real-time monitoring of temperature histories. The results show that, monitoring on local strain in health monitoring systems of RYSB can effectively provide the information on fatigue stresses. The range of the equivalent fatigue stress on the monitoring location of the bridge is currently low, mainly due to varying traffic loading and temperature. There exists significant correlation between varying temperature and mean value of fatigue stress. Effect of the passing of heavy trucks on bridge fatigue is quite significant since the value of the cumulative fatigue damage generated by heavy trucks is 10 to 100 times larger than that by normal traffic. Therefore, the effect on fatigue cumulative damage due to heavy trucks or overloaded vehicles needs to be monitored and paid much attention to. __________ Translated from Journal of Southeast University (Natural Science Edition), 2007, 37(2): 280–286 [译自: 东南大学学报(自然科学版)]     

水平双向地震作用下薄壁方形截面钢桥墩#br# 抗震性能试验及实用算法研究

钢板局部失稳破坏是钢桥墩结构典型的地震失效模式之一,但目前仍缺乏既能考虑局部失稳影响,又可方便用于工程设计的结构地震反应计算方法。通过对2个薄壁方形截面钢桥墩试件施加沿斜向的水平反复荷载,研究结构的地震破坏形式和抗震性能;在钢材修正双曲面滞回模型的基础上,通过对结构参数分析结果的数据拟合,建立考虑钢板局部失稳影响的方形截面钢桥墩纤维模型算法。结果表明：薄壁方形截面钢桥墩结构在水平双向地震作用下,首先会发生墩底钢板局部失稳,在荷载达到最高点后墩底焊缝处出现超低周疲劳破坏,在两种地震破坏的共同作用下结构承载力迅速下降;通过与试验结果的对比,验证结构地震有效损伤域Ld内的纤维单元采用等效滞回模型能准确反映钢板的局部失稳效应,为工程设计提供一种高精度的实用计算方法。     

福州海峡国际会展中心结构健康监测系统设计与分析研究

结构健康监测已成为重大建筑结构工程安全监测重要技术手段,是当前土木工程界研究热点。福州海峡国际会展中心结构健康监测系统包括了四大系统:传感器系统、数据采集和传输系统、数据处理及控制系统和结构健康评估系统。研究总体的设计原则和各子系统设计原则和方法,给出了基于钢屋盖结构体系的安全评估方法。     

黄河口模型试验厅钢屋架健康监测系统研究

介绍了黄河口模型试验厅钢屋架结构健康监测系统研究的主要成果,综合评述了该钢屋架工程健康监测的主要进展和关键问题,主要内容包括:构成系统的各个主要子系统、监测项目的确定和布点策略、监测仪器的选择、数据的采集、数据的传输和处理、结构损伤状态识别等。     

Health monitoring of flexural steel structures based on distributed fibre optic sensors

In our previous study, a distributed long-gauge fibre optic sensing system (with the ability to obtain effective average strain, or macro-strain, distributions) for practical adaptation in civil structural health monitoring was developed and verified. The present paper is devoted to proposing an integrated health monitoring scheme for elastic beam-like structures, where flexure dominates structural responses, based on static testing and measurements using the developed sensors. A series of experimental investigations on steel beams with different levels of damage are first carried out. The static strain measurements from distributed sensors are characterised and some concerns on the data processing and feature extraction are discussed. On the basis of the extracted features, structural health monitoring (SHM) investigations are deployed in three parts: damage identification with no requirement for a structural analytical model, parametric estimation based on finite element (FE) models, and evaluation of structural global behaviour. By comparing to traditional transducers such as linear variable displacement transducers (LVDTs) and foil ‘point’ strain gauges, the ability and ascendancy of the sensors developed here for SHM purposes are verified. A comprehensive health monitoring strategy for steel flexural structures based on the distributed strain sensors array is proposed finally.     

Structural parameter identification and damage detection for a steel structure using a two-stage finite element model updating method

A two-stage eigensensitivity-based finite element (FE) model updating procedure is developed for structural parameter identification and damage detection for the IASC-ASCE structural health monitoring benchmark steel structure on the basis of ambient vibration measurements. In the first stage, both the weighted least squares and Bayesian estimation methods are adopted for the identification of the connection stiffness of beam-column joints and Young’s modulus of the structure; then the damage detection is conducted via the FE model updating procedure for detecting damaged braces with different damage patterns of the structure. Comparisons between the FE model updated results and the experimental data show that the eigensensitivity-based FE model updating procedure is an effective tool for structural parameter identification and damage detection for steel frame structures.     

重庆奥林匹克体育中心钢网架安全监测及数据分析

本文介绍了重庆市奥林匹克体育中心体育场钢结构安全检测系统的构成特点．分析了钢桁架在吊装、塔架拆除、屋面设备安装后的应变监测数据,在结构形成后进行了连续温度监测,并分析了温度对结构内力的影响。     

Corrosion damage assessment and monitoring of large steel space structures

Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.     

Seismic performance and collapse prevention of concrete-filled thin-walled steel tubular arches

The primary objective of this paper is to investigate the seismic behaviour of concrete-filled steel tubular (CFST) arches using incremental dynamic analysis (IDA). A nonlinear elastic–plastic finite element model is developed using OpenSees software and is verified with a shaking table test. Single-record IDA studies indicate that a CFST arch undergoes global dynamic instability when subjected to ground motions of increasing intensity levels. During this process, either dynamic elastic buckling or dynamic elastic–plastic buckling may occur. Dynamic strength, which is defined as the capacity for preventing global dynamic instabilities of CFST arches, is determined with a series of multi-record IDA calculations. A lower bound equation that takes into account the effect of slenderness ratio, axial compression ratio, and included angle is proposed for the prediction of the dynamic strength of CFST arches.