石英丝弹性元件的研究与制作

本文介绍了烧焊熔凝石英的实验设备,拉制及焊接石英丝、石英弹簧等元件的技术。同时,还简要介绍了熔凝石英的物理、化学特性和应用情况。     

基于BOTDR的基坑变形分布式监测实验研究

在基坑开挖和支护过程中深部土体的水平位移监测是一项十分重要的工作。布里渊光时域反射计（BOTDR）是近年来国际上研发成功的一项新型的分布式光电传感技术。通过该技术,将传感光纤按照一定的工艺粘贴在埋置于土体中的测斜管上,由传感光纤实测的应变分布,可以实现深部土体水平位移的在线监测。通过室内的模型模拟试验,由实测的光纤应变可以准确地得到测斜管上任意一点的水平位移。结合南京市某深基坑进行的现场试验,探讨了基于BOTDR的分布式光纤传感器应用于基坑深部土体水平位移监测的具体施工工艺,验证了该技术在实际工程中应用的可行性。     

光纤光栅锚杆传感在隧道应变监测中的技术研究

针对隧道施工和运行长期监测的需要和当前的岩土监测所用电磁传感器的不足,基于分析了光纤布拉格光栅(FBG)传感监测原理和实现方法,在直径为22 mm的普通螺纹钢上设计和制作了隧道应力应变监测用的FBG锚杆传感器,并分析FBG探测锚杆轴向应变的原理。通过试验室和公路隧道现场对已制作的FBG锚杆进行动态测试与应用,效果良好,并突出了FBG锚杆传感灵敏度高、稳定性好、测量范围大、结构简单和能在野外岩土结构工程进行长期有效监测等优点。     

Experimental study of deformable connection consisting of friction device and rubber bearings to connect floor system to lateral force resisting system

This paper presents experimental and numerical studies of a full‐scale deformable connection used to connect the floor system of the flexible gravity load resisting system to the stiff lateral force resisting system (LFRS) of an earthquake‐resistant building. The purpose of the deformable connection is to limit the earthquake‐induced horizontal inertia force transferred from the floor system to the LFRS and thereby to reduce the horizontal floor accelerations and the forces in the LFRS. The deformable connection that was studied consists of a friction device (FD) and carbon fiber‐reinforced laminated low‐damping rubber bearings (RB), denoted as the FD + RB connection. The test results show that the force‐deformation responses of the FD + RB connection are stable under quasi‐static sinusoidal and earthquake loading histories and dynamic sinusoidal loading histories. The FD + RB connection force‐deformation response is approximated with a bilinear elastic‐plastic force‐deformation response with kinematic hardening. The FD is axially stiff, compact, easy‐to‐assemble, and able to accommodate the FD + RB connection kinematic requirements. The FD elastic stiffness controls the FD + RB connection elastic stiffness. The FD friction force controls the force when the FD + RB connection force‐deformation response transitions from elastic to post elastic. The RB provide predictable and reliable post‐elastic stiffness to the FD + RB connection. The machining tolerances for the FD components, the “break‐in” effect, the sliding history, and the dwell time affect the FD friction force. Numerical simulation results for a 12‐story reinforced concrete wall building with FD + RB connections under seismic loading show that a reduction of the FD friction force increases the FD + RB connection deformation demand.     

采用非线性纤维梁单元法的钢管混凝土组合框架动力响应分析

钢管混凝土结构已经广泛应用于我国高层和超高层建筑中,为研究该类结构的抗震性能,分别采用分离模量法和统一模量法对某13层钢管混凝土框架结构进行抗震性能分析,研究不同地震波作用下组合框架的模态和多遇地震下的弹性动力时程,对比组合框架顶点位移反应、加速度反应、层间侧移及动力放大系数等。研究结果表明,分离模量法和统一模量法建模方法在分析钢管混凝土框架抗震动力特性上总体相差不大,但前者可以考虑材料弹塑性,从而对结构弹塑性进行分析,而后者在弹塑性阶段需要用全曲线表达式,尚需进一步的研究。     

Effect of ground motion selection methods on seismic collapse fragility of RC frame buildings

Variation in the seismic collapse fragility of reinforced concrete frame buildings predicted using different ground motion (GM) selection methods is investigated in this paper. To simulate the structural collapse, a fiber‐element modelling approach with path‐dependent cyclic nonlinear material models that account for concrete confinement and crushing, reinforcement buckling as well as low cycle fatigue is used. The adopted fiber analysis approach has been found to reliably predict the loss in vertical load carrying capacity of structural components in addition to the sidesway mode of collapse due to destabilizing P–Δ moments at large inelastic deflections. Multiple stripe analysis is performed by conducting response history analyses at various hazard levels to generate the collapse fragility curves. To select GMs at various hazard levels, two alternatives of uniform hazard spectrum (UHS), conditional mean spectrum (CMS) and generalized conditional intensity measure (GCIM) are used. Collapse analyses are repeated based on structural periods corresponding to initial un‐cracked stiffness and cracked stiffness of the frame members. A return period‐based intensity measure is then introduced and applied in estimating collapse fragility of frame buildings. In line with the results of previous research, it is shown that the choice of structural period significantly affects the collapse fragility predictions. Among the GM selection methods used in this study, GCIM and CMS methods predict similar collapse fragilities for the case study building investigated herein, and UHS provides the most conservative prediction of the collapse capacity, with approximately 40% smaller median collapse capacity compared to the CMS method. The results confirm that collapse probability prediction of buildings using UHS offers a higher level of conservatism in comparison to the other selection methods. Copyright © 2017 John Wiley & Sons, Ltd.     

爆炸荷载下FRP约束钢筋混凝土结构动力响应研究现状

纤维增强复合材料（Fiber Reinforced Polymer,简称"FRP"）具有轻质高强、耐腐蚀、耐疲劳和低导热系数等优点,现已广泛应用于土木工程各领域。针对FRP约束钢筋混凝土结构的抗爆性能,通过综述近年来国内外爆炸荷载下FRP约束钢筋混凝土结构动力响应的研究现状及进展,表明FRP材料的约束对钢筋混凝土结构的抗爆性能有显著的提高作用。此外,从相关理论研究、试验研究和数值模拟3个方面介绍了主要成果。针对现有成果,对爆炸荷载下FRP约束钢筋混凝土结构动力响应研究提出了需要进一步研究和解决的问题,可为后续研究提供一定的参考。     

活性粉末混凝土板抗冲击性能试验研究

为了研究常温养护条件下活性粉末混凝土(RPC)板的抗冲击性能,对3块RPC板和3块普通钢筋混凝土(RC)板进行14 m高度下的落锤冲击试验,利用高速动态采集系统对落锤冲击过程中动态加速度和动态支座反力、混凝土板的应变进行采集,通过记录数据并对比分析了RPC板和RC板抗冲击性能的差异。试验结果表明:与普通RC板相比,RPC板的落锤冲击持续时间明显延长,冲击速度增大,冲量明显增加;冲击加速度峰值、平均冲击力及最大冲击力均减小;RPC板四角所承受的动态反力幅值明显大于RC板;RPC板的最大应变均大于RC板。分析混凝土板的破坏情况,发现RPC板正面接触冲击部位只出现较小的冲击坑,未出现RC板的穿透性破坏,且RPC板背面的裂缝数量均少于RC板,宽度也明显小于RC板。试验结果,表明常温养护条件下RPC板的抗冲击性能明显高于RC板,且随着钢纤维掺量的增加,RPC板的抗冲击性能逐渐增强,相比较于普通混凝土,RPC材料更加适用于受落石冲击危害的地区。     

基于RWTLS的Allan方差算法简化

Allan方差是现在应用最广泛的随机误差辨识方法之一。大量的试验表明Allan方差可有效地分离出导航过程中的多项随机误差,但是Allan方差也有自身的局限性。针对Allan方差在处理大数据量时计算效率低下、辨识度受粗差的影响较大的问题,本文提出了简化Allan方差算法的方案。首先,在确保Allan方差计算准确的前提下,以提高Allan方差计算效率为目的,对Allan方差算法进行简化;然后,利用抗差加权整体最小二乘（RWTLS）模型的迭代算法对简化后的Allan方差辨识结果进行抗差拟合处理;最后,以光纤式惯性测量单元（IMU）为分析对象,设计试验方案对简化后的Allan方差进行验证。     

FRP（钢绞线）加筋混凝土梁正截面受弯承载力计算

纤维增强复合筋、不锈钢绞线等高强材料作为混凝土梁的受力筋可以充分发挥强度高、耐腐蚀性能好等优点,在土木工程中得到了广泛应用。为了分析此类高强材料加筋混凝土梁的受弯性能,在平截面假定基础上,对混凝土和受力纵筋分别采用混凝土Hongnestad模型和线弹性模型,通过平衡条件,推导了FRP（钢绞线）加筋混凝土梁受弯承载力的计算公式,并与国内外82根简支梁的试验结果进行了对比。研究结果表明：加筋混凝土梁抗弯强度试验值与理论值之比的平均值为1.07,标准差为0.14。建议公式可以较好地计算FRP（钢绞线）加筋混凝土梁的受弯承载力。实际工程构件抗弯截面设计时,建议安全配筋率取1.4倍平衡配筋率,设计截面弯矩取0.625倍理论受弯承载力,以使构件具有足够安全储备。