Seismic energy dissipation under variable amplitude loading for rectangular RC members in flexure

The energy dissipation characteristics of reinforced concrete members that exhibit both strength and stiffness deterioration under imposed displacement reversals were investigated. To do this, 24 symmetrically reinforced concrete rectangular specimens were tested under stable variable and random variable amplitude inelastic displacement cycles. Stable variable amplitude tests were employed to determine the low‐cycle fatigue behavior of specimens where the loading sequence was the major variable. A 2‐parameter fatigue model was developed in order to express the variation of the dissipated energy in displacement cycles with the cumulative hysteretic energy. This model was then used to predict the energy dissipation of test specimens subjected to random variable amplitude displacement cycles simulating severe seismic excitations. It has been demonstrated that the remaining energy dissipation capacity for the next displacement cycle was dependent on the relative relationship between the maximal displacement cycle and the energy dissipated along the completed displacement path. The plastic energy dissipation capacity of reinforced concrete members is both displacement path dependent and cumulative hysteretic energy dependent.     

钢混凝土组合梁低周反复荷载试验研究

本文基于钢－混凝土组合梁的低周反复荷载试验，对其破坏形态、滞回曲线、抗震延性、耗能能力、刚度退化、变形恢复能力等抗震性能进行了较为深入的研究，研究结果表明：钢－混凝土组合梁具有良好的抗震性能。     

摩擦消能支撑钢框架结构的弹塑性地震反应时程分析

本文分析了摩擦消能支撑及框架主体结构弹塑性本构关系，并给出了动力时程分析的计算方法。同时，对六层钢框架模型做了各种工况下的地震反应时程分析。结果表明，摩擦消能支撑钢框架（FEDBF）比抗弯钢框架（MRF）的地震作用明显降低，尤其在强震作用下效果更加明显。     

Field testing of stiffened deep cement mixing piles under lateral cyclic loading

Construction of seaside and underground wall bracing often uses stiffened deep cement mixed columns (SDCM). This research investigates methods used to improve the level of bearing capacity of these SDCM when subjected to cyclic lateral loading via various types of stiffer cores. Eight piles, two deep cement mixed piles and six stiffened deep cement mixing piles with three different types of cores, H shape cross section prestressed concrete, steel pipe, and H-beam steel, were embedded though soft clay into medium-hard clay on site in Thailand. Cyclic horizontal loading was gradually applied until pile failure and the hysteresis loops of lateral load vs. lateral deformation were recorded. The lateral carrying capacities of the SDCM piles with an H-beam steel core increased by 3-4 times that of the DCM piles. This field research clearly shows that using H-beam steel as a stiffer core for SDCM piles is the best method to improve its lateral carrying capacity, ductility and energy dissipation capacity.     

设置黏滞阻尼器的钢结构实用减震设计方法

黏滞阻尼器作为一种有效的消能减震装置,已在钢结构建筑中得到了大量应用.然而由于钢结构的延性和阻尼特征,实用的钢结构附加黏滞阻尼器设计方法仍需深度探讨.文中提出一种基于黏滞阻尼器延性需求的减震设计方法.首先,根据钢结构需求量化层间位移角性能目标及目标附加阻尼比,计算黏滞阻尼器延性需求,并确定黏滞阻尼器布置数量、进行控制效...     

考虑梁端耗能能力影响的钢框架结构易损性分析

一般采用梁柱焊接节点钢框架结构在遭遇强烈地震地震作用下,结构倒塌破坏可能由于是耗能能力不足所导致。以某钢框架结构为算例,选取20条实际地震动记录,对结构进行易损性分析,对比不同损伤指标和不同梁端构造形式的钢框架结构抗震性能差异。研究显示:对梁柱焊接的普通钢框架结构,其倒塌破坏是由于结构耗能能力不足所导致的,评价结构抗震性能不仅需考虑结构变形能力,尚需同时考虑结构耗能能力;对于改进形式的钢框架结构,结构耗能能力得到显著提高,使得位移首超破坏先于累积损伤破坏,此时基于变形的评价结果更加可靠。     

消能支撑框架结构的低周往复水平荷载试验仿真分析方法

本文提出了低周往复水平荷载试验仿真分析方法，该法既不同于弹塑性地震反应时程分析，又不同于常见的弹塑性静力分析。它能模拟低周往复水荷载试验的过程，既避免了地震波频谱的影响又体现了水平荷载的往复作用，可用于计算结构和构件的滞回曲线、截面的屈服顺序及相应的荷载和位移，尤其适用于分析消能支撑框架结构等耗能减震结构。本文用此方法分析了在框架柱轴压比超过限值要求时消能支撑的作用。     

基础隔震结构的减震耗能特性分析

根据基础隔震理论,在钢筋沥青隔震礅的基础上,提出一种新型钢结构隔震礅,设计和制作了缩尺房屋模型,并对其进行振动台试验。通过对隔震结构模型的动力特性、地震响应及能量平衡分析,绘制试验过程中的加速度及能量时程曲线,研究钢隔震礅应用于低层框架结构的减震耗能能力。大量工程实例可以看出该隔震礅隔震效果显著,制作简单、价格低廉、耐久性好,适于在广大村镇地区低层框架结构中推广使用。试验表明:隔震结构模型在不同的地震作用下,加速度折减系数处在0.24~0.51之间,且结构的阻尼耗能在振动台试验中占总输入能量的60%~70%,对结构耗能起主导作用,说明该基础隔震装置不仅具有较好的减震耗能特性能,对于控制隔震层的位移也有好的效果。     

反复荷载下型钢混凝土柱受扭损伤试验研究

为研究型钢混凝土柱在反复荷载下的受扭损伤,完成了11根型钢混凝土柱和1根钢筋混凝土柱复合受扭试验。通过试验观察了构件的受力过程和破坏特征,研究两种不同型钢混凝土柱的裂缝开展与分布规律。基于能量守恒定律,考察了柱截面配钢形式、扭弯比、轴压比、混凝土强度等级、配箍率以及配钢率对累积损伤的影响。研究结果表明:型钢混凝土柱的损伤演变分为3个阶段:弹性阶段、弹塑性阶段和破坏阶段;配钢形式、扭弯比和配箍率是影响型钢混凝土柱损伤程度的重要因素;配型钢,降低扭弯比和提高配箍率对于损伤指标分别最大降低了22.1%、14.3%和14.0%;损伤指标受轴压比、配钢率和混凝土强度等级影响程度较小。     

Cyclic behavior and failure mechanism of self‐centering energy dissipation braces with pre‐pressed combination disc springs

A new type of bracing system composed of friction energy dissipation devices for energy dissipation, pre‐pressed combination disc springs for self‐centering and tube members as guiding elements is developed and experimentally studied in this paper. The mechanics of this system are explained, the equations governing its hysteretic responses are outlined and large‐scale validation tests of two braces with different types of disc springs are conducted under the condition of low cyclic reversed loading. The experimental results demonstrate that the proposed bracing system exhibits a stable and repeatable flag‐shaped hysteretic response with an excellent self‐centering capability and effective energy dissipation throughout the loading protocol. Furthermore, the maximum bearing force and stiffness are predicted well by the equations governing its mechanical behavior. Fatigue and destructive test results demonstrate that the proposed bracing system can maintain stable energy dissipation and self‐centering capabilities under large deformation cyclic loading even when the tube members exceed the elastic limit and that a larger bearing capacity is achieved by the system that has disc springs without a bearing surface. Copyright © 2016 John Wiley & Sons, Ltd.     

加劲圆环耗能器性能的试验研究

本文提出了“耗能器应具有多道耗能减震防线”的思想,研究了设计了国圆环耗能器,并对其进行了循环加试验,考察了耗能器的工作用耗能性能。     

Cyclic shear behaviour of steel box girders: experiment and analysis

An experimental investigation of the cyclic shear behaviour of steel box girders was conducted on one‐quarter scale models, comprising of two specimens with longitudinally unstiffened webs and one specimen with longitudinally stiffened webs. All the specimens exhibited ductile behaviour. The tests evidenced significant increases in the shear strength and energy dissipation capacity regarding the use of thicker webs and the provision of longitudinal web stiffeners. The web stiffeners also enhanced the stable hysteresis behaviour without substantial degradation in the energy dissipation due to pinching. The test results are compared with the shear behaviour simulated by inelastic large deformation analysis incorporated with a sophisticated constitutive model. The hysteresis behaviour, peak cyclic shear stresses, energy dissipation, and deformation shapes of the three specimens are satisfactorily predicted by the analysis. It is verified that the presented analytical method can be used precisely for further investigations of box girders in shear. Copyright © 2002 John Wiley & Sons, Ltd.     

新型方钢管混凝土框架节点抗震性能试验研究

本文介绍了新型方钢管混凝土柱与钢梁节点在低周反复荷载作用下的试验结果,研究了内填混凝土、加劲肋长度和梁柱相对尺寸等对节点抗震性能的影响,并提出了有关的设计建议。     

轻钢龙骨房屋足尺模型低周反复试验

对一个具有完整边界条件的轻钢龙骨体系房屋足尺模型进行了低周反复试验。试验主要考虑转角墙对轻钢龙骨体系房屋抗震性能的影响,以及龙骨壁厚对复合承载墙体破坏模式的影响,研究房屋在低周反复荷载作用下的变形过程、破坏特征和滞回性能等。试验结果表明:轻钢龙骨房屋的抗震性能与自攻螺钉连接性能密切相关。自攻螺钉的连接性能决定了轻钢龙骨房屋的耗能机制、耗能能力以及破坏形态。由于螺钉在该结构中分布广泛,使得结构的侧向变形能力和耗能能力较好,同时,试验验证了轻钢龙骨复合墙体抗剪承载力计算时关于自攻螺钉连接受力方向的假设和受力大小分析结果的正确性。     

Experimental and analytical investigations of steel panel dampers for seismic applications in steel moment frames

A ductile Vierendeel frame can be constructed by incorporating steel panel dampers (SPDs) into a moment‐resisting frame (MRF). Thus, the stiffness, strength, and ductility of the lateral force–resisting system can be enhanced. The proposed 3‐segment SPD possesses a center inelastic core (IC) and top and bottom elastic joints. This paper discusses the mechanical properties, capacity design method, and buckling‐delaying stiffeners for the SPDs through the use of cyclic loading tests on 2 specimens. Tests confirm that SPDs' cyclic force vs deformation relationships can be accurately predicted using either the Abaqus or PISA3D model analyses. The paper also presents the capacity design method for boundary beams connected to the SPDs of a typical SPD‐MRF. The seismic performance of an example 6‐story SPD‐MRF is evaluated using nonlinear response history analysis procedures and 240 ground accelerations at 3 hazard levels. Results indicate that under 80 maximum considered earthquake ground accelerations, the mean‐plus‐one standard deviation of the shear deformation of the ICs in the SPDs is 0.055 rad, substantially less than the 0.11 rad deformational capacity observed from the SPD specimens. The experimental cumulative plastic deformation of the proposed SPD is 242 times the yield deformation and is capable of sustaining a maximum considered earthquake at least 8 times before failure. This paper introduces the method of using one equivalent beam‐column element for effective modeling of the 3‐segment SPD. The effects of the IC's relative height and stiffness on the overall SPD's elastic and postelastic stiffness, elastic deformation limits, and inelastic deformational demands are discussed.     

往复荷载作用下矩形钢管混凝土压弯构件承载力计算

本文基于往复荷载作用下矩形钢管混凝土压弯构件的实验结果，比较了国内外比较典型的设计规范(程)，包括英国BS5400(1979)、美国ACI318—99(1999)和AISC-LRFD(1999)、日本AIJ(1997)、欧洲EC4(1994)、中国GJB4142-2000(2001)和福建省地方标准(送审稿)，及本文数值方法在计算往复荷载作用下矩形钢管混凝土压弯构件承载力的差异。结果表明，在进行往复荷载作用下矩形钢管混凝土压弯构件承载力计算时，各种计算方法获得的承载力都偏于安全，其中，数值计算结果与实验结果最接近，GJB4142—2000(2001)的计算结果与实验结果吻合程度稍差，ACI318—99(1999)，EC4(1994)和福建省地方标准(送审稿)的计算结果比实验结果约低20％，而BS5400(1979)、AISC—LRFD(1999)和AIJ(1997)的计算结果比实验结果总体上低30％以上。本文结果可供进行矩形钢管混凝土结构设计时参考。     

Low cyclic fatigue and hysteretic behavior of U‐shaped steel dampers for seismically isolated buildings under dynamic cyclic loadings

Energy dissipation devices are necessary for base‐isolated buildings to control the deformation in the isolation system and to dissipate the earthquake‐induced energy. U‐shaped steel dampers (also known as U‐dampers) dissipate energy through plastic deformation of specially designed U‐shaped steel elements. This type of device can be installed at several locations in the isolation system. U‐dampers have been widely used in Japan for different types of isolated structures, such as hospitals, plants and residential buildings, since the 1995 Kobe Earthquake. Previous research has used static tests to estimate the performance of U‐dampers. However, the ultimate plastic deformation capacities and hysteretic behaviors of full‐scale U‐dampers under dynamic excitations still remain unclear. In addition, it is unclear whether the initial temperature has an effect on the hysteretic behavior and plastic deformation capacity of U‐dampers. In this paper, two series of dynamic loading tests of U‐dampers were conducted to evaluate the issues described earlier. The major findings of the study are (i) the loading speed has little effect on the plastic deformation capacity of U‐dampers; (ii) method to evaluate the ultimate plastic deformation capacities of U‐shaped steel dampers of different sizes is established using a Manson–Coffin relation‐based equation that is based on the peak‐to‐peak horizontal shear angle γ_t, which is defined as the lateral deformation amplitude (peak‐to‐peak amplitude) divided by the height of the dampers; (iii) the loading rate and the initial temperature have a minimal effect on the hysteretic behavior of the U‐dampers; and (iv) a bilinear model is proposed to simulate the force‐deformation relationships of the U‐dampers. Copyright © 2014 John Wiley & Sons, Ltd.     

Experimental study of the seismic behavior of partially concrete‐filled steel bridge piers under bidirectional dynamic loading

The seismic behavior of steel bridge piers partially filled with concrete under actual earthquake conditions was investigated by using 20 square section specimens subjected to static cyclic loading tests and single‐directional and bidirectional hybrid loading tests. Acceleration records of two horizontal NS and EW directional components for hard (GT1), medium (GT2), and soft grounds (GT3), obtained during the 1995 Kobe earthquake, were adopted in dynamic tests. Experimental results clearly showed that maximum and residual displacements under actual earthquake conditions cannot be accurately estimated by conventional single‐directional loading tests, especially for GT2 and GT3. A modified admissible displacement was proposed on the basis of bidirectional loading test results. The concrete fill can effectively improve the seismic resistance performance if the concrete inside the steel bridge piers is sufficiently high in quantity. Copyright © 2013 John Wiley & Sons, Ltd.     

圆不锈钢管混凝土短柱轴压承载力性能研究

为了研究圆不锈钢管混凝土柱轴压承载力性能,在试验的基础上,利用有限元软件ABAQUS建立合理的有限元模型,并进行不同混凝土强度和约束效应系数参数化分析及不锈钢管和核心混凝土的轴力分配研究.结果表明:壁厚相同时,CFSST短柱的极限荷载增大幅度由大到小为:30MPa增加到40 MPa,50 MPa增加到60 MPa,40...     

Test and analysis of reinforced concrete (RC) precast shear wall assembled using steel shear key (SSK)

Reinforced concrete (RC) precast shear walls are extensively applied in practical engineering, owing to their fast construction speed. However, because of the transport conditions, RC precast shear walls have to be separated into small wall segments during the factory prefabrication procedure before being assembled on site. Typically, wet-type jointing methods are adopted to link the segments, which is time-consuming and results in unreliable post-pouring area strength. To overcome this problem, the novel scheme of the steel shear key (SSK) featuring steel shear panels and combined fillet and plug welding is proposed. Three RC precast shear wall specimens with different linking strength, termed as weakened SSK wall, standard SSK wall, and strengthened SSK wall, respectively, and an integrated shear wall specimen were designed. Quasi-static cyclic loading was applied to investigate the specimens' dynamic properties. The test results suggest the prefabricated wall segments equipped with SSKs showed reliable stiffness and bearing capacity and were improved in energy dissipation ability, compared with conventional shear walls. As the shear stiffness and number of equipped SSKs increased, the specimens exhibited higher strength, but their ductility and energy dissipation were slightly decreased. Most importantly, the standard SSK wall specimen could achieve satisfactory bearing capacity and deformability and is thus recommended for precast building structures. Finite element method (FEM) models were established to validate the test results, and parametric study analysis was conducted based on the coupling ratio of the SSK walls. Finally, an appropriate coupling ratio range is recommended for practical engineering applications.