Analysis of the Application of Static Load Test in Bridge Bearing Capacity Testing

This article uses real engineering projects as examples to analyze how static load test technology is applied in testing the bridge-bearing capacity.The analysis covers aspects such as testing section layout,test load and efficiency coefficient,loading plan,evaluation optimization,test result modification,and result evaluation.The aim is to support the accurate detection and evaluation of bridge-bearing capacity.

Technical Analysis of Highway Bridge Static Load Test

Highway bridges are an important part of the transportation industry and can promote social economic construction and development.In actual operation,highway bridges are often damaged due to overload and natural factors,which tend to affect the safety and shorten the service life of these bridges.Assessing the overall state and performance of highway bridges is therefore a key element.Static load test,which is a type of sustainable detection experiment,has many advantages,including low cost,high efficiency,and high accuracy.In this paper,the bridge structure is analyzed through the application of theoretical calculations and relevant comparisons,so as to judge the operating state of the bridge.

Static Load Test Detection of Continuous Rigid- Frame Railway Bridge

The quality of the continuous rigid-frame railway bridge is related to the safety of train operation,so it is necessary to test its stiffness,strength,and other indicators.Static load test is a common technique for bridge inspection.This article summarizes the purpose of the static load test for a continuous rigid-frame railway bridge,including the required equipment,operation methods,etc.,and lists examples to analyze the operation process and precautions of static load test,hoping to provide reference information for relevant personnel.

Mechanical properties and supporting effect of CRLD bolts under static pull test conditions

A device for supporting soft rock masses combined with a constant resistance structure characterized by constant resistance and large deformation at the end of a steel bar, known as the constant resistance and large deformation（CRLD） bolt, has recently been developed to counteract soft rock swelling that often occurs during deep mining. In order to further study the mechanical properties of the CRLD bolt, we investigated its mechanical properties by comparison with the conventional strength bolt（rebar） using static pull tests on many aspects, including supporting capacity, elongation, radial deformation, and energy absorption. The tests verified that the mechanical defects of the rebar, which include the decrease of bolt diameter, reduction of supporting capacity, and emergence and evolution of fracture until failure during the whole pull process, were caused by the Poisson＇s ratio effect. Due to the special structure set on the CRLD bolt, the bolt presents a seemingly unusual phenomenon of the negative Poisson＇s ratio effect, i.e., the diameter of the constant resistance structure increases while under-pulling. It is the very effect that ensures the extraordinary mechanical properties, including high resistance, large elongation, and strong energy absorption. According to the comparison and analysis of numerical simulation and field test, we can conclude that the CRLD bolt works better than the rebar bolt.

Application of bi-directional static loading test to deep foundations

Bi-directional static loading test adopting load cells is widely used around the world at present, with increase in diameter and length of deep foundations. In this paper, a new simple conversion method to predict the equivalent pile head load-settlement curve considering elastic shortening of deep foundation was put forward according to the load transfer mechanism. The proposed conversion method was applied to root caisson foundation in a bridge and to large diameter pipe piles in a sea wind power plant. Some new load cells, test procedure, and construction technology were adopted based on the applications to different deep foundations, which could enlarge the application scopes of bi-directional loading test. A new type of bi-directional loading test for pipe pile was conducted, in which the load cell was installed and loaded after the pipe pile with special connector has been set up. Unlike the conventional bi-directional loading test, the load cell can be reused and shows an evident economic benefit.

Research on Dynamic and Static Test Methods for Evaluating the Poisson's Ratio of Orien ted Strand Board

In this article,dynamic method and static method of testing Poisson's ratio of OSB(Oriented Strand Board)were proposed.Through modal and static numerical analyses,the position where the transverse stress is equal to zero was determined.The binary linear regression method was applied to express the gluing position of the strain gauge as a relational express ion that depended on the length-width ratio and width-thickness ratio of the canti-lever plate.Then the longitudinal and transverse Poisson's ratios of OSB were mea sured by the given dynamic and static methods.In addition,the test results of OSB Poisson's ratio were analyzed with the probability distribution of random variables.The results showed that using the proposed dynamic method and static method,the test results for longitudinal and transverse Poisson's ratios of OSB were quite consistent,despite the gluing position of the strain gauges being different.And these OSB Poisson's ratios were accorded with that obtained by the axial tensile method and the four-point bending method.OSB longitudinal and transverse Poisson's ratios followed Weibull distribution.

Intermittent disturbance mechanical behavior and fractional deterioration mechanical model of rock under complex true triaxial stress paths

Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensional high-stress and even causing disasters.Therefore,a novel complex true triaxial static-dynamic combined loading method reflecting underground excavation damage and then frequent intermittent disturbance failure is proposed.True triaxial static compression and intermittent disturbance tests are carried out on monzogabbro.The effects of intermediate principal stress and amplitude on the strength characteristics,deformation characteristics,failure characteristics,and precursors of monzogabbro are analyzed,intermediate principal stress and amplitude increase monzogabbro strength and tensile fracture mechanism.Rapid increases in microseismic parameters during rock loading can be precursors for intermittent rock disturbance.Based on the experimental result,the new damage fractional elements and method with considering crack initiation stress and crack unstable stress as initiation and acceleration condition of intermittent disturbance irreversible deformation are proposed.A novel three-dimensional disturbance fractional deterioration model considering the intermediate principal stress effect and intermittent disturbance damage effect is established,and the model predicted results align well with the experimental results.The sensitivity of stress states and model parameters is further explored,and the intermittent disturbance behaviors at different f are predicted.This study provides valuable theoretical bases for the stability analysis of deep mining engineering under dynamic loads.

模拟骨骼应变测试系统搭建及其标定研究

为研究人体骨骼损伤的力学机理和应变测试方法,建立了适用于40%玻璃纤维增强的聚苯硫醚(PPS)模拟骨的应变测试系统,并对测试系统进行了标定试验研究。本文对测试系统各组成部分原理和技术指标进行分析,利用万能试验机对试件进行多次加载,分析应变测试系统在拉伸、压缩及三点弯曲3种工况下的静态标定参数,结果表明:本文构建的PPS模拟骨应变测试方法可有效表征骨损伤的应变情况,本文研究可为创伤弹道学和病理学中的骨损伤试验研究提供参考。

风电叶片多点分级静力加载无模型自适应控制及实现

兆瓦级风电叶片静力加载试验目前一般采用多点同步逐级加载的方法实现。为解决静力加载试验多点同步协调控制及各加载点力耦合的问题,提出了一种不基于加载对象数学模型的静力加载自适应控制算法,并通过伺服绞车+力传感器+三坐标测量仪+控制采集装置搭建了试验系统,通过PLC根据算法调整伺服电机的转速以实时调整加载载荷的变化率,从而实现各加载点载荷同步、匀速、稳定变化。加载系统采用竖向加载方式,在满足试验要求的基础上大大节约了占地面积,经现场试验,加载时间控制在3 min以内,加载同步性控制在1%以内,最大载荷可达300 kN,对各种叶片适应性良好,具有一定的通用性。

径向箔片气体轴承静态刚度影响因素试验分析

箔片气体轴承的静态刚度直接影响气体轴承工作过程中的稳定性和可靠性。针对影响径向箔片气体轴承静态刚度的因素进行试验研究,通过对比测试比较不同因素对径向箔片气体轴承静态刚度数值的影响。试验结果表明:测试位置、底层箔片的厚度、轴承的种类和底层箔片的拱高均对气体轴承的静态刚度有一定的影响。

基于工业数据挖掘的ESD软失效分析

针对电子产品出货后出现ESD软失效而导致的退货现象,文章通过机器学习算法分析产品ICT电性能测试参数、生产线ESD防护监控数据和产品ESD软失效的相关性。集成算法模型经过优化,分类准确率达到0.88,可以用于量产电子产品的ESD软失效的识别和出货风险管控。同时,利用ESD防护监控点风险指数数据集可以提高产品ESD软失效的识别准确率(8.6%)。安装部署基于物联网技术的静电放电防护监控系统,对管控电子产品生产过程中的ESD软失效风险以及控制出货风险是很有帮助的,可以提高电子制造业防静电管控的智慧化水平。

Solid Model Bridge Static Damage Monitoring Based on GBSAR

Bridge deformation monitoring usually adopts contact sensors,and the implementation process is often limited by the environment and observation conditions,resulting in unsatisfactory monitoring accuracy and effect.Ground-Based Synthetic Aperture Radar(GBSAR)combined with corner reflectors was used to perform static load-loaded deformation destruction experiments on solid model bridges in a non-contact manner.The semi parametric spline filtering and its optimization method were used to obtain the monitoring results of the GBSAR radar’s line of sight deformation,and the relative position of the corner reflector and the millimeter level deformation signals under different loading conditions were successfully extracted.The deformation transformation model from the radar line of sight direction to the vertical vibration direction was deduced.The transformation results of deformation monitoring and the measurement data such as the dial indicator were compared and analyzed.The occurrence and development process of bridge deformation and failure were successfully monitored,and the deformation characteristics of the bridge from continuous loading to eccentric loading until bridge failure were obtained.The experimental results show that GBSAR combined with corner reflector can be used for deformation feature acquisition,damage identification and health monitoring of bridges and other structures,and can provide a useful reference for design,construction and safety evaluation.

Mechanical properties of rock under coupled static-dynamic loads

Rock drilling machine,INSTRON testing system,and SHPB device are updated to investigate the characteristics of rocks at great depth,with high loads from overburden,tectonic stresses and dynamic impacts due to blasting and boring.It is verified that these testing systems can be used to study the mechanical properties of rock material under coupled static and dynamic loading condition and give useful guidance for the deep mining and underground cavern excavation.Various tests to determine the rock strength,fragmentation behavior,and energy absorption were conducted using the updated testing systems.It is shown that under coupled static-dynamic loads,if the axial prestress is lower than its elastic limit,the rock strength is higher than the individual static or dynamic strength.At the same axial prestress,rock strength under coupled loads rises with the increasing strain rates.Under coupled static and dynamic loads,rock is observed to fail with tensile mode.While shear failure may exist if axial prestress is high enough.In addition,it is shown that the percentage of small particles increases with the increasing axial prestress and impact load based on the analysis of the particle-size distribution of fragments.It is also suggested that the energy absorption ratio of a specimen varies with coupled loads,and the maximum energy absorption ratio for a rock can be obtained with an appropriate combination of static and dynamic loads.

Effects of Microstructure on Quasi⁃Static Transverse Loading Behavior of 3D Circular Braided Composite Tubes

The effects of microstructure on quasi-static transverse loading behavior of 3D circular braided composite tubes were studied. Transverse loading tests were conducted. Transverse load-deflection curves were obtained to analyze the effects of braiding parameters including the braiding angle, the wall thickness, and the diameter on the transverse loading of 3D circular braided composite tubes. Breaking loads, moduli and strengths had also been used to describe the transverse loading behaviors. The failure morphologies were shown to reveal damage mechanisms. From the results, the increase in braiding angle, wall thickness and diameter increases the ability of anti-deformation and breaking load of braided tubes. The breaking load of specimen with a braiding angle of 45° is about 1.68 times that of specimen with a braiding angle of 15°. The breaking load of specimen with 4 layers of yarns is about 2.15 times that of specimen with 2 layers of yarns. The breaking load of the tube with a diameter of 25.5 mm is about 2.39 times that of the tube with a diameter of 20.5 mm.

北斗Ⅲ变形观测系统性能测试与工程应用

针对传统工程观测方法存在的基准点选取困难、自动化程度低及可靠性差等问题,设计了北斗Ⅲ高精度变形观测系统。为验证该系统在地表变形观测中的观测精度及应用效果,通过模拟试验分析观测精度与通视条件、定位时段的关系,并将上述观测系统与传统方法进行对比。结果表明,在试验区域内,保证通视条件且定位时段为12∶00~16∶00时,BDS-Ⅲ变形观测系统垂直向定位精度优于1.5 mm,水平向定位精度优于1 mm,相同条件下,水平向定位精度由于垂直向定位精度;该系统能很好的保证观测数据的完整性,得到的观测值与传统水准观测值基本一致,适合用于高精度、自动化地表变形观测工程。

框架结构外围护墙酚醛板保温饰面层抗震性能试验研究

制作了4榀钢筋混凝土框架试件,并砌筑填充墙和粘贴酚醛板保温饰面层。通过拟静力试验,研究了不同砌体填充墙的框架,在采用不同粘贴方式和不同粘贴率时粘贴酚醛板保温饰面层的抗震性能及框架的受力特性。试验表明:1)酚醛板保温饰面层和填充墙与框架共同工作,形成斜撑效应共同承担水平地震作用。若框架的受力机理发生改变,将发生框架柱剪切破坏或节点破坏。2)由于酚醛板强度低,地震作用时,粘贴在框架梁柱上的酚醛板发生破坏,保温饰面层与基层脱离,粘贴在顶层梁和边柱上的饰面层,以及填充墙为加气混凝土砌块砌体且粘贴率为20%时粘贴在其他各层梁上的饰面层,地震作用时将会脱落,其余构件上饰面层虽然已与基层脱离但未脱落,应适当增加顶层梁及边柱上塑料锚钉或保持粘贴率不小于50%。3)填充墙为加气混凝土砌块砌体时,填充墙角部砌体受压破坏,粘贴在填充墙上的饰面层空鼓脱落。粘贴形式对饰面层的破坏程度影响不大,粘贴率越小破坏程度越严重。

Process Monitoring and Terminal Verification of Cable-Stayed Bridges with Corrugated Steel Webs under Contruction

In this paper,the construction process of a cable-stayed bridge with corrugated steel webs was monitored.Moreover,the end performance of the bridge was verified by load test.Owing to the consideration of the bridge structure safety,it is necessary to monitor the main girder deflection,stress,construction error and safety state during construction.Furthermore,to verify whether the bridge can meet the design requirements,the static and dynamic load tests are carried out after the completion of the bridge.The results of construction monitoring show that the stress state of the structure during construction is basically consistent with the theoretical calculation and design requirements,and both meet the design and specification requirements.The final measured stress state of the structure is within the allowable range of the cable-stayed bridge,and the stress state of the structure is normal and meets the specification requirements.The results of load tests show that the measured deflection values of the mid-span section of the main girder are less than the theoretical calculation values.The maximum deflection of the girder is−20.90 mm,which is less than−22.00 mm of the theoretical value,indicating that the girder has sufficient structural stiffness.The maximum impact coefficient under dynamic load test is 1.08,which is greater than 1.05 of theoretical value,indicating that the impact effect of heavy-duty truck on this type of bridge is larger.This study can provide important reference value for construction and maintenance of similar corrugated steel web cable-stayed bridges.

基于列车制动防滑原理的静态防滑测试系统

针对地铁列车制动系统防滑测试,设计了一种基于制动防滑原理的静态防滑测试系统。该静态防滑测试系统通过向列车制动系统发送对应的速度方波信号来模拟列车运行过程中检测到的速度信号。通过观察和对比输入模拟的滑行速度和采集到的防滑阀的压力变化,判断和检测列车制动系统的防滑性能是否正常工作,从而实现列车制动系统的静态防滑测试。

考虑地震动持时效应的加载制度对结构的影响

历次大地震震害表明,地震动持时对工程结构累积损伤有显著影响,长持时地震动作用下结构损伤明显加重,因此,确定地震动持时对结构地震反应及损伤的定量影响成为热门研究课题。拟静力试验是模拟结构地震反应的重要手段,但目前其加载制度未考虑地震动持时影响。选取考虑俯冲区长持时地震动作用的加载制度和规范建议的加载制度,利用OpenSees有限元软件建立RC柱结构模型,对比分析了FB、DB、HB梁柱单元,选择与试验符合较好的HB梁柱单元进行模拟,结果分析表明:长持时加载制度会不同程度增大结构的耗能退化和刚度退化,规范建议的加载制度不能体现长持时地震动作用下结构的反应。

角度扭矩传感器标定与检测系统设计

针对某企业角度扭矩传感器输出性能标定和检测的需求,设计一种角度扭矩传感器标定与检测系统。该系统能够实现对角度扭矩传感器角度和扭矩信号的标定、自动检测。采用基于工控机PCI接口的数据采集控制系统,实现对标定和检测过程数据的实时采集以及对伺服电机的精确控制;采用基于双位置气缸的装载系统,实现对传感器标定对象的自动切换;使用LabVIEW编程软件完成对传感器标定检测流程实时控制和显示等功能的设计。在角度扭矩传感器的角度和扭矩完成灵敏度标定后,对其静态输出性能进行检测,得出角度扭矩传感器的非线性误差、迟滞误差等均在允许范围内。大量重复性试验结果表明,角度的合成标准不确定度为0.0720°,扭矩的合成标准不确定度为0.0413 N·m,说明所设计系统能够满足企业对于角度扭矩传感器性能标定和检测功能的测试要求。