Ultimate strength and ductility of stiffened steel tubular bridge piers

This paper presents the ultimate strength and ductility of steel tubular bridge piers with the inner cruciform plates, the stiffener plates, the concrete-filled sections and the outer tube subjected to monotonic and cyclic horizontal loads. Numerical analyses were carried out using the finite element package MARC. Firstly, to check the validity of the numerical analysis, the analytical results of the steel tubular columns with the inner cruciform plates, the concrete filled sections and the outer tube were compared with the previous experimental results. Secondly, the effects of the radius-to-thickness ratio parameter and the slenderness ratio parameter on seismic performance (the ductility, the ultimate strength etc.) of these steel tubular piers were examined. Numerical results indicated that the steel column with inner cruciform plates was able to improve the ultimate strength and ductility of the steel tubular piers.     

FEA on hysteretic behavior of concrete-filled round-ended stainless steel tubular bridge piers

为研究圆端形不锈钢管混凝土桥墩的滞回性能,采用有限元分析软件ABAQUS,建立了圆端形不锈钢管混凝土桥墩的精细化模型,对比研究其与圆端形普通钢管混凝土桥墩受力性能的差异,并对影响其滞回性能的主要因素进行参数分析。研究发现：采用不锈钢与普通钢的圆端形钢管混凝土桥墩承载力相当,但由于不锈钢存在较为显著的应变强化现象,前者的荷载-位移曲线下降更为平缓,圆端形不锈钢管在加载后期仍能对核心混凝土提供较好的约束作用;随截面长宽比增加,圆端形不锈钢管混凝土桥墩的水平承载力明显增加,但位移延性明显下降;随含钢率增加,桥墩的抗侧刚度、水平承载力、位移延性均明显增加;随轴压比增加,桥墩水平承载力略有降低,而位移延性明显下降;而核心混凝土强度对桥墩的滞回性能影响有限。     

内钢板中空方形钢管混凝土叠合柱轴压力学性能研究

为研究中内钢板中空方形钢管混凝土（CFST）叠合柱的轴压力学性能,以内钢板与钢管的强度和壁厚为参数对8个叠合短柱进行轴压试验,以截面尺寸、钢管内外混凝土强度、钢材强度、纵筋与钢管用钢量分配为参数对81个叠合短柱进行有限元分析,对典型构件受力全过程、各部分接触作用以及承载力进行研究。在美国结构设计规范ANSI/AISC 360-16、欧洲钢结构设计规范BS EN 1994-1-1、GB 50936—2014《钢管混凝土结构技术规范》和T/CECS 663—2020《钢管混凝土加劲混合结构技术规程》的组合柱承载力计算公式中增加内钢板承载力项,得到内钢板中空方形CFST叠合构件的轴压承载力计算式。结果表明：轴压荷载作用下,内钢板中空方形CFST叠合柱钢管外混凝土、内钢板、钢管、纵筋以及核心混凝土能协同工作;内钢板强度与壁厚对构件承载力、延性和刚度影响均较小;截面尺寸和混凝土强度对构件承载力贡献最大,但构件延性随着混凝土强度的增大而降低。在T/CECS 663—2020和ANSI/AISC 360-16的组合柱承载力计算公式中增加内钢板贡献项计算得到的承载力值与试验和有限元结果最为接近。     

Seismic performance of new-type box steel bridge piers with embedded energy-dissipating shell plates under tri-directional seismic coupling action

Accurate numerical models are necessary to evaluate the seismic performance and load-bearing mechanism of new-type box steel bridge piers with embedded energy-dissipating shell plates under tri-directional seismic coupling action. Numerical simulations of seismic performance under six types of tri-directional seismic coupling action was conducted. The effects of this stress on the seismic performance of the new-type steel bridge piers was evaluated through analysis of damage mode, hysteresis curve, skeleton curve, stiffness and strength degradation characteristic, and energy-dissipating capacity. This study also compared the numerical analysis with experimental results in order to validate the accuracy of the proposed finite element model. Based on this model, the range of relevant parameters expanded and 88 numerical specimens were analysed for seismic performance, producing further information about the influence of thickness and curvature of the embedded shell plate, spacing of transverse stiffening ribs of the shell, axial compression ratio, and slenderness ratio. Results showed that tri-directional seismic coupling action significantly affects the specimen’s deformation capacity; the embedded shell plate effectively improves the piers’ load-carrying and deformation capacity; and the thickness of the embedded shell plate, width-to-thickness ratio of the wall plate, axial compression ratio, and slenderness ratio significantly affect the seismic performance of the new-type steel bridge piers. To promote the ease of seismic design of new-type box steel bridge piers, this study used theoretical analysis and numerical simulation to calculate equations for the minimum height of the energy-dissipating zone of the bottom embedded shell plate. Finally, formulas were also established to calculate the relevant stability bearing capacity and displacement ductility factor of the new-type steel bridge piers under tri-directional seismic coupling action in order to improve their seismic design.     

不同结构形式墩柱耗能及变形能力的比较

为考察钢筋混凝土桥墩和钢管混凝土桥墩的抗震性能,基于相同的含钢率和轴压比,首次进行了两种不同结构形式的桥墩拟静力对比试验（试件包括2个钢管混凝土墩柱和1个钢筋混凝土墩柱）,并考察了轴压比对钢管混凝土桥墩抗震性能的影响。试验结果表明,相同含钢率和轴力情况下,钢管混凝土墩柱的耗能能力和变形能力都优于钢筋混凝土墩柱,前者的耗能能力约为后者的4.5倍,变形能力约为后者的1.4倍;随着轴压比的增大,钢管混凝土墩柱延性有所下降。     

单边高强螺栓连接方套方中空夹层钢管混凝土柱组合节点抗震性能试验研究

为了深入研究单边高强螺栓连接中空夹层钢管混凝土柱组合节点的抗震性能和破坏机理,对4个方套方中空夹层钢管混凝土柱与钢-混凝土组合梁单边高强螺栓端板连接节点进行了低周反复加载试验,以端板形式和柱截面空心率为主要试验参数,考察了节点破坏模式和组合楼板裂缝分布规律,研究节点滞回曲线、连接弯矩-转角关系、刚度和承载力退化、延性和...     

带肋圆管截面钢桥墩的延性影响因素研究

为研究带肋圆管截面钢桥墩在水平反复荷载作用下的延性影响因素,首先通过与试验结果对比,确认有限元分析方法的有效性,然后对承受水平反复荷载作用下的圆管钢桥墩进行一系列参数研究,详细讨论钢桥墩径厚比、纵向加劲肋数量以及纵向加劲肋长细比等对钢桥墩极限承载力和延性性能的影响。研究结果表明,随着钢桥墩径厚比和纵向加劲肋长细比的减小,圆管钢桥墩的延性性能得到很大改善。与配置4根纵向加劲肋相比,配置6根肋后的延性提高效果并不明显,而配置8根肋可以显著提高钢桥墩的延性性能。     

Strength and ductility evaluation of steel bridge piers with linearly tapered plates

Important issues on the application of linearly tapered steel plates to highway bridge piers are discussed in this paper based on extensive experimental work. The factors that affect the seismic resisting performance of tapered plate steel columns were examined. The main factors considered are: (1) types of tapering mold line (outer, central, and inside tapering); (2) tapering ratio (or the slope of thickness change); (3) stiffeners’ rigidity; and (4) tapered stiffeners. To this end, four groups of specimens were tested under cyclic lateral loads and constant axial load. The columns with the outside taper plates were found to have the best strength and ductility characteristics among the three types of mold lines. In the case of different tapering ratios, the largest ductility was observed in the specimens with the tapering ratio slightly less than or equal to unity. The stiffeners’ rigidity ratio of around 3.0 was found to give the best ductility performance in columns with both constant thickness and varying thickness stiffeners. The test results were compared with a recently proposed design equation for limit strain of box columns with tapered plates. Finally, finite element analyses were performed and comparisons between the test and the analyses’ results of several test specimens are presented.     

Seismic performance of precast hollow bridge piers with different construction details

Currently the design scheme of precast hollow concrete bridge piers will be adopted in bridge design in China, but there is no code including specific design details of precast segmental piers in high seismic risk area. For comparative study of seismic performance of the hollow bridge piers which had different design details, six specimens of hollow section bridge pier were designed and tested. The specimens consist of the monolithic cast-in-place concrete bridge pier, precast segmental prestressed pier with cast-in-place joint and precast segmental concrete bridge pier with dry joints. Results show that all specimens have good displacement capacity. The bridge pier with bonded prestressed strands exhibits better energy dissipation capacity and higher strength. The un-bonded prestressed strand bridge pier displays less residual plastic displacement and energy dissipation capacity. The bridge pier with both bonded prestressed strands at the edge of the section and un-bonded in the center of the section not only exhibits more ductility capacity and less residual plastic displacement, but also shows better energy dissipation capacity. Compared with experimental results of prestressed bridge columns, analytical result demonstrates the developed numerical analysis model would provide the reasonable and accurate results.     

高强钢筋实现低配筋铁路桥墩延性抗震研究

我国铁路桥梁目前仍在大量使用只配有护面钢筋的低配筋桥墩,这类桥墩的变形能力差,在地震作用下易发生脆性破坏。为了提高这类桥墩的抗震性能,提出了采用高强钢筋实现低配筋桥墩延性抗震的思路。对1个配置HRBF500钢筋的低配筋桥墩试件进行低周反复荷载试验,研究试件的破坏形态、滞回特性、刚度退化、耗能性能和延性等。结果表明,试件的破坏模式为延性破坏。在试验研究的基础上,进一步分析高强钢筋实现低配筋桥墩延性抗震的机理。     

局部外包钢管钢筋混凝土桥墩力学性能分析

运用大型有限元软件ABAQUS对局部钢管约束钢筋混凝土桥墩的有限元计算模型进行低周反复荷载作用下全过程的非线性有限元分析,通过分析滞回曲线、骨架曲线及等效刚度退化曲线的特点发现,局部钢管约束钢筋混凝土高桥墩具有很好的延性性能,可以作为桥墩延性抗震设计的一种备选方案。     

螺纹钢法兰连接预制装配桥墩抗震性能研究

为研究在水平荷载作用下螺纹钢法兰连接预制装配桥墩的抗震性能,设计制作一个整体现浇桥墩、两个分别采用承插式和非承插式方案的螺纹钢法兰连接预制桥墩.通过开展拟静力加载试验,对比研究螺纹钢法兰连接预制装配桥墩与整体现浇桥墩的破坏模式、荷载-位移曲线特征.基于试验,建立三个桥墩的有限元数值模型与试验进行对比,两者结果吻合较好....     

Q345中厚缺口板的断裂试验

对18个厚度为26mm的单边V型缺口钢板进行了断裂试验,研究了刻弧半径r对低合金钢Q345中厚板断裂模式的影响。试验显示:裂纹起始于三轴强约束的缺口边缘厚度中面,裂纹沿厚度贯通后迅速沿薄弱截面宽度扩展,宏观断裂面大致垂直于加载方向,断口粗糙且有大量韧窝。缺口根部刻弧愈尖锐的试件,断裂延性愈差。缺口根部刻弧平缓的试件,净截面平均开裂强度略高。     

Seismic performance improvement of circular steel columns using precompressed concrete-filled steel tube

This paper presents a new method aimed at improving seismic resisting characteristics of circular-shaped steel columns representing highway bridge piers and an experimental investigation carried out to validate it. In this method, a special compression member is placed in the middle of the pier in order to take the axial load from the superstructure. As a result, the influence of axial load on the inelastic buckling deformation of plates can be greatly controlled. The special compression member consists of a precompressed concrete-filled steel tube (PC-CFT). Six specimens were tested to check the seismic performances of the proposed column system. It was clear from the test results that the specimens with PC-CFT could deform even up to ten times of their yield displacements without significant load deterioration. They also showed improved ultimate strength, ductility and energy absorption capacities than the corresponding benchmark specimens.     

中空型外壁钢板-混凝土组合桥塔塔柱承载力研究

以某跨海大桥原型设计提出的一种新型中空型外壁钢板-混凝土组合桥塔塔柱为背景,设计制作了4个中空型外壁钢板-混凝土组合塔柱试件。通过轴心受压试验,研究中空型外壁钢板-混凝土组合桥塔塔柱破坏过程,并分析混凝土强度、钢板厚度、连接件型式等参数对试件轴压性能的影响。采用ABAQUS软件进行有限元模拟,分析不同结构型式和设计参数(混凝土强度、钢板强度和钢板厚度)对组合塔柱受力性能的影响。研究表明：中空型外壁钢板-混凝土组合塔柱具有优异的承载能力和延性,其承载能力和延性与内外壁钢板-混凝土组合塔柱相当,明显优于普通钢筋混凝土柱;提高混凝土强度、钢板强度和增加钢板厚度均能够提高组合塔柱承载力,但对结构刚度提高不明显。研究成果可为大跨桥梁设计提供参考。     

内置十字加强板圆形钢管短柱在轴压作用下的力学性能研究

通过运用有限元分析软件MARC,分析了内置十字加强板圆形钢管短柱在轴压作用下弹塑性力学性能,目的是为了确定该类桥墩的有效失稳长度和短柱极限承载力及极限应变。分析时考虑了焊接残余变形和残余应力的影响,考察的参数有径厚比、Ls/D等参数。通过研究提出了短柱的有效失稳长度、极限强度和极限应变的关系式,为桥墩抗震性能评价提供了理论基础。     

桥梁拉吊索用不锈钢钢丝腐蚀性能及斜拉索时变可靠度研究

对零应力普通镀锌钢丝和施加0%,20%,30%,40%强度的应力不锈钢钢丝,分7,20,40 d进行中性盐雾试验,研究零应力普通镀锌钢丝和不同应力水平下不锈钢钢丝的质量损失率、强度、延性和断口形貌的变化。通过算例分析了分别采用普通镀锌钢丝和不锈钢钢丝作斜拉桥拉索时可靠指标随时间的变化。结果表明:零应力下普通镀锌钢丝的质量损失率是不锈钢钢丝的30倍以上;不锈钢钢丝的质量损失率随着应力的增加而增加,高应力下的不锈钢钢丝更容易腐蚀;短期腐蚀对钢丝的极限强度影响不大,不锈钢钢丝随着应力的增加延性变差;随着腐蚀的增加,普通镀锌钢丝和不锈钢钢丝的拉伸端口呈现出脆性增加的趋势,普通钢丝的端口形貌由微裂纹向长宽裂纹发展,而不锈钢钢丝由于腐蚀较轻,只是出现了微裂纹;采用普通镀锌钢丝作斜拉桥拉索时可靠指标随时间的下降速度比采用不锈钢钢丝快。     

内填部分混凝土箱形截面钢桥墩的滞回性能研究

首先,利用试验方法对内填部分混凝土箱形截面钢桥墩在承受水平反复荷载作用下的滞回性能进行研究,探讨翼缘宽厚比参数和混凝土填充率对钢桥墩滞回性能的影响。然后,采用弹塑性有限元分析方法,对试验结果进行数值模拟。研究结果表明,钢桥墩的延性随着翼缘宽厚比的减小和混凝土填充率的提高而得到显著提高。由数值模拟得到的试件的滞回曲线、钢板局部屈曲模态等,与试验结果吻合较好。     

碳纤维增强复合材料约束矩形空心墩抗震性能试验研究

为了研究纤维增强复合材料(FRP)约束钢筋混凝土(RC)空心截面桥墩的抗震性能,对水平单向和双向荷载作用下,剪跨比分别为4和8的CFRP约束RC矩形空心墩进行拟静力试验。分析不同试件的破坏形态、滞回曲线、水平力和位移延性。结果表明:通过CFRP布环包约束试验空心墩的塑性铰区,可降低墩柱的破坏位置、减轻损伤程度,并改变剪跨比较小墩柱的破坏形态;明显改善水平双向荷载作用下剪跨比较大矩形空心墩的滞回性能和延性,但是对水平力的提高小于20%。