预压低碳钢和不锈钢空心钢管与钢管混凝土柱的冲击性能

研究受静力横向荷载和预压轴向冲击荷载下低碳钢和不锈钢空心钢管与钢管混凝土柱的性能。在柱中部或1/4处施加横向荷载。近来,在University of Western Sydney和University of Wollongong进行了3组试验,获得了受横向静力荷载和预压或无预压冲击荷载下的低碳钢和不锈钢空心钢管与钢管混凝土柱的性能。介绍关于对柱施加轴向和横向荷载的第三组试验的试验结果。研究静力和冲击荷载下低碳钢和不锈钢空心钢管与钢管混凝土柱的有限元建模方法。使用有限元分析软件ABAQUS建立一个包括非线性材料性能、钢的加强角性能和预压荷载三维的非线性有限元模型,从而模拟静力和冲击试验。研究主要目的是比较低碳钢和不锈钢空心钢管与钢管混凝土柱性能的试验结果和数值结果。此外,比较冲击荷载下内填钢管和空心钢管的性能。荷载-挠度响应和极限强度的试验结果与有限元结果较为一致。同时,比较静力和冲击荷载下空心与不锈钢钢管混凝土柱和空心与低碳钢钢管混凝土柱的结果。一般来讲,与低碳钢试验构件相比,不锈钢试验构件的强度更高,耗能能力更好。     

装配式空心剪力墙抗震性能研究

对4个装配式空心剪力墙试件进行拟静力试验,模拟了不同的轴压比和剪跨比对试件抗震性能的影响。通过低周往复加载试验得到试件的滞回曲线,并分析其延性、耗能性能和刚度特征。试验结果表明:装配式空心剪力墙的抗震性能和普通钢筋混凝土剪力墙抗震性能相似,且空心孔洞和水平拼接缝不会削弱墙体的受力性能,各个试件均表现出良好的延性和耗能能力,因此可以通过提高水平拼接缝的位置改善墙体抗震性能。     

预制装配式钢筋混凝土一体化剪力墙抗震性能研究及构造方案优化

针对预制装配式剪力墙结构,提出了内置空心管的混凝土填充墙与实体剪力墙墙肢一同浇筑生产、安装施工的预制一体化剪力墙结构。通过5个外形尺寸、墙肢和连梁配筋相同的混凝土双肢剪力墙的拟静力试验,探究了无填充、砌块砌体填充和一体化整体填充的剪力墙抗震性能,总结了这三类墙体的破坏形态、受力特点、承载与变形能力、刚度、延性和耗能能力的特点。试验结果表明：预制一体化剪力墙在水平往复荷载作用下发生弯剪破坏,相比于无填充墙试件和砌体填充试件,其抗侧刚度和受剪承载力有明显提高,同时具有良好的抗震性能。最后,基于OpenSEES平台对拟静力试验结果进行了有限元验证,得到了吻合程度较好的滞回曲线、骨架曲线及墙肢纵筋应变;根据试验结果与有限元分析,提出了预制一体化混凝土剪力墙结构合理的填充墙构造方案。     

钢管混凝土组合节点的抗震性能及其影响因素研究

采取柱端加载模式进行了4组钢管混凝土柱单边螺栓端板连接节点的拟静力加载试验,考察了柱截面空心率和端板连接形式对节点破坏模式、柱端载荷-位移滞回曲线、弯矩-转角关系曲线和耗能能力的影响。结果表明,平齐端板连接和外伸端板连接节点试件的破坏模式基本相同;在相同空心率条件下,平齐端板连接节点柱边缘的裂缝相较于外伸端板连接节点试件更少,外伸端板连接节点试件的极限承载力、耗能能力、初始刚度、抗弯承载力和初始转动刚度要高于平齐端板连接节点试件;在相同端板连接条件下,空心率较低的节点试件的极限承载力、耗能能力、初始刚度、抗弯承载力和初始转动刚度要高于空心率较高的节点试件。在极限状态下,4种节点试件的等效粘滞阻尼系数ξ_c都保持在0.204～0.235之间,耗能能力优于钢筋混凝土柱节点,并与钢管混凝土柱外加强环节点的耗能能力相当,4种节点试件具有较强的耗能能力。     

开孔板式屈曲约束支撑拟静力滞回性能试验研究

提出一种开孔板式屈曲约束支撑(PPBRB),该支撑核心单元为开孔的一字形钢板,约束套管采用钢板焊接而成,并在端部加设加劲套箍。设计制作4支PPBRB试件,对其进行拟静力滞回性能试验,研究开孔板式屈曲约束支撑滞回耗能能力、承载力性能以及累积塑性变形能力。研究结果表明:该支撑构造合理,滞回曲线饱满,滞回性能稳定,耗能性能优良;支撑端部构造设计合理,能够保证支撑正常工作;铰接与固接的连接方式均能保证支撑性能得到有效发挥。     

FRP加固桥梁RC短柱拟静力及网络拟动力试验

针对桥梁钢筋混凝土(RC)短柱刚度大而剪跨比小的特点,通过试验方法研究其抗震性能。制作了7个受剪承载力不足的短柱试件,在恒定轴力作用下分别进行未加固短柱、碳纤维(CFRP)加固短柱和玻璃纤维(GFRP)加固短柱的拟静力试验和网络拟动力试验。分析各试件的滞回曲线、骨架曲线、累积耗能曲线和刚度退化曲线,研究其延性、强度和刚度,并初步比较了拟静力试验结果与拟动力试验结果的差异。试验结果表明:FRP加固RC短柱能够在基本不改变结构动力特性的条件下,有效地增加延性,改善抗震性能;试件在拟动力试验中耗能能力小于拟静力试验中耗能能力。研究成果可为加固RC结构的抗震分析和工程设计提供参考。     

多角柱和角单元抗压能力的试验和数值分析

通过采用INSTRON材料试验机对规则多角柱和菱形柱在拟静力轴压下的耗能性能进行研究。研究圆心角对角单元的变形模式和均压力的影响。通过数值分析研究拟静力和动力轴压下多角柱和角单元的抗压能力。通过数值计算得到的多角柱的压力和变形模式与试验结果吻合较好。另外,基于试验中观察到的结果,对耗能变形机制进行讨论。     

松浦大桥新型浮式防船撞装置

以松浦大桥为背景,研发一种新型浮式防船撞装置。介绍防船撞装置的关键技术,并给出其关键构造措施。装置内部填充轻质泡沫实现结构的自浮性能,内、外钢箱之间填充橡胶圈提高装置的耗能能力,同时采用复合钢板和可靠连接构造使结构具有良好的耐久性。该防撞装置在船桥撞击下可有效地保护桥梁和船舶结构的安全。     

装配式空心剪力墙拟静力试验研究

对2片不同轴压比的装配式空心剪力墙进行了拟静力试验,描述了该墙的破坏过程,分析了墙体的破坏特征、滞回特性、耗能能力等抗震性能。结果表明,装配式空心剪力墙主要呈弯剪破坏;随着轴压比的增大,墙体承载力增大,延性提高,耗能能力提高,刚度退化加快;装配式空心剪力墙的抗震性能良好,应用于三层及以下低轴压比结构时,具有较大的安全储备。最后,结合试验结果与相关文献结论,给出了该结构形式的装配式空心剪力墙的弹性刚度计算式修正系数。     

预制保温带暗斜撑钢筋混凝土剪力墙抗震性能试验研究

提出预制保温带暗斜撑钢筋混凝土剪力墙,墙体内部预留4个三角形空心区域,在其内填充保温板,沿墙体对角线方向设置斜向钢筋。进行剪跨比分别为1.0、1.5及2.0的保温暗斜撑混凝土剪力墙试件的低周反复荷载试验,分析了不同试件的破坏形态、滞回曲线、骨架曲线、承载能力、变形能力、刚度退化及耗能能力;为与同尺寸普通钢筋混凝土剪力墙的抗震性能开展对比分析研究,进行了剪跨比为1.5的普通混凝土剪力墙试件的拟静力试验;并采用ABAQUS有限元分析软件对试件抗震性能进行数值模拟分析。结果表明,对于剪跨比相同的保温暗斜撑剪力墙和普通剪力墙,前者的承载力略有降低,但延缓了裂缝的开展,延性得到改善,耗能能力显著提升,抗震性能较优;对于保温暗斜撑剪力墙,随着剪跨比的增大,承载力降低,变形能力增强,刚度退化减缓,耗能能力增加;有限元模型可以较好地模拟试件的抗震性能。     

Comparative experimental study of hot-rolled and cold-formed rectangular hollow sections

Square and rectangular hollow sections are generally produced either by hot-rolling or cold-forming. Cross-sections of nominally similar geometries, but from the two different production routes may vary significantly in terms of their general material properties, geometric imperfections, residual stresses, corner geometry and material response and general structural behaviour and load-carrying capacity. In this paper, an experimental programme comprising tensile coupon tests on flat and corner material, measurements of geometric imperfections and residual stresses, stub column tests and simple and continuous beam tests is described. The results of the tests have been combined with other available test data on square and rectangular hollow sections and analysed. Enhancements in yield and ultimate strengths, beyond those quoted in the respective mill certificates, were observed in the corner regions of the cold-formed sections—these are caused by cold-working of the material during production, and predictive models have been proposed. Initial geometric imperfections were generally low in both the hot-rolled and cold-formed sections, with larger imperfections emerging towards the ends of the cold-formed members—these were attributed largely to the release of through thickness residual stresses, which were themselves quantified. The results of the stub column and simple bending tests were used to assess the current slenderness limits given in Eurocode 3, including the possible dependency on production route, whilst the results of the continuous beam tests were evaluated with reference to the assumptions typically made in plastic analysis and design. Current slenderness limits, assessed on the basis of bending tests, appear appropriate, though the Class 3 slenderness limit, assessed on the basis of compression tests, seems optimistic. Of the features investigated, strain hardening characteristics of the material were identified as being primarily responsible for the differences in structural behaviour between hot-rolled and cold-formed sections.     

Thermo-hydro-mechanical characterisation of a bentonite-based buffer material by laboratory tests and numerical back analyses

This paper presents some laboratory tests performed on the bentonite used as buffer material in the engineered barrier experiment in Kamaishi mine in Japan and a collective effort of four research groups to characterise the coupled thermo-hydro-mechanical behaviour of the bentonite by comparing numerical calculations with the laboratory test results. Each research group used finite element programs with constitutive models capable to simulate both liquid and vapour flux of water, heat transfer, volume change, swelling pressure and mechanical deformation. Numerical calibrations were performed against results obtained from three types of laboratory tests: water infiltration tests, thermal gradient tests and swelling pressure tests. Parameter values, which could not be directly measured in laboratory tests, were obtained with these calculations.     

Creep and time-dependent damage in argillaceous rocks

This paper presents the results of laboratory tests on the time-dependent behaviour of three rocks characterized by a high proportion of clay particles. The viscosity of these sedimentary rocks was studied under different loading conditions in uniaxial compression: static or cyclic creep tests and quasistatic tests (low-loading strain rate) were performed across various orientations of fabric planes.The quasistatic tests showed similarities in the mechanical response of these three argillaceous rocks: a late phase of dilation and a linear development of volumetric deformation before the beginning of unstable crack propagation. The development of secondary and tertiary creep phases during the creep tests highlighted the existence of a deviatoric stress threshold, below which only primary creep is observed. Long-term creep tests also showed that the volumetric variation is not constant during the development of viscoplastic deformations.A microstructural analysis of thin sections extracted from specimens after the tests, gave evidence of cataclastic and granular creep. Damage to the argillaceous matrix occurs and no cracks were observed in the quartz and carbonate grains. This evidence was also demonstrated for tests with loading at a high strain rate.Finally, this study highlights the significant viscoplasticity of argillaceous rocks. The mechanical properties deteriorate rapidly when crack propagation becomes unstable and the viscoplastic strains seem to be due to clay particle slips, known as granular creep.     

武昌中风化红砂岩特性和嵌岩桩承载力确定

通过对中风化红砂岩室内抗压强度试验、现场载荷试验、抽芯试验,结合场地工程勘察资料,确定岩基承载力特征值。人工挖孔扩底桩以该层作为桩端持力层,并进行了桩的静载荷试验。本文对这些试验中的大量数据进行了总结和归纳,特别是对中风化红砂岩的一些变形特性进行了分析,确定了在实际工程中有重要参考价值的数据,同时也指出了规范中相应条款中过于保守的问题,并提出了修改意见。     

边坡岩土体抗剪强度原位试验研究

针对碟子沟风井场地边坡特征,在边坡典型位置的岩石与土层界面和软弱泥岩夹层处分别进行了原位剪切试验,获得了相应的抗剪强度指标。通过与滑带土相同工况下的室内试验强度指标对比,发现室内试验指标较原位剪切试验获得的内聚力和内摩擦角低,并分析了室内外试验结果差异的原因。试验研究表明,边坡岩土体的大型原位剪切试验对边坡稳定性分析和工程治理优化具有重要价值。     

Comparison of sand liquefaction in cyclic triaxial and simple shear tests

The liquefaction resistance and correction factors K_σ and K_α of Nakdong River sand obtained from cyclic triaxial (CTX) tests were compared with those determined by cyclic simple shear (CSS) tests to ascertain the importance of the reduction factor C_r and correction factors K_σ and K_α in liquefaction evaluations, especially in view of the lack of comparative liquefaction assessments based on different laboratory test apparatuses. All samples used for the comparisons were obtained from the same type of sand by using similar preparation methods and they were subjected to similar stress states to minimize the number of factors influencing the comparison results; moreover, the apparatuses used in the two tests were manufactured by the same company and all tests were conducted by a single operator. It was found that the liquefaction resistance in CTX tests was always greater than that in CSS tests. Furthermore, C_r varied from 0.63 to 0.36, and it depended on the relative density D_r and initial static shear ratio α. K_σ, which increased with the normal effective stress σ′_nc in CTX tests, was identical to K_σ observed in CSS tests when α was increased up to 0.1. By contrast, K_α in the CSS tests was 58%–97% of K_α measured in the CTX tests, and it depended on the combined effect of D_r, σ′_nc, and α. The relationship between K_α and α in both CTX and CSS tests was well represented by a parabolic function. Moreover, the differences in K_α values between the CTX and CSS tests were also found to be a parabolic function of α. This information can be used for converting CTX (or CSS) values into equivalent CSS (or CTX) values.     

卸荷状态下黏性土的变形和强度试验研究

南京河西地区原状黏性土应力路径试验表明,不排水情况下,侧向卸荷试验得到的割线模量E5′0要大于轴向加荷试验得到的割线模量E5 0,且大致有E5′0=1.7 E5 0关系;轴向加荷和侧向卸荷条件下得到的有效抗剪强度指标基本一致。上述结论在工程实例数值模拟分析中的应用明显改善了地面沉降预测结果与实测结果的吻合程度。     

Structural analysis of two King-post timber trusses: Non-destructive evaluation and load-carrying tests

The misunderstanding of the overall behaviour of traditional timber trusses can result in incorrect strengthening interventions or, frequently, on their replacement. Timber roof structures need a more concise knowledge of the real behaviour to determine internal loads and control the load transfer. For that, laboratory tests on scaled or full-scale specimens of members, connections and trusses are needed.In this paper, an accurate geometric and mechanical evaluation of the timber elements of two King-post timber trusses, based on grading results with data gathered from non-destructive tests (NDT), including mechanical evaluation of the modulus of elasticity in bending (MoE), followed by full-scale carrying tests were performed. The trusses were reassembled in laboratory and submitted to a series of symmetric and non-symmetric cyclic tests, according to the Limit States. Strengthening techniques evaluated in precedent research steps were used in a second phase of the load-carrying tests.     

膜材料性能及其对结构的影响

首先对几种常见的膜结构破坏形式进行了阐述分析.在世博轴局部足尺模型试验中,将数值计算结果同试验结果进行了对比分析,发现两者相差很大,经分析认为主要是由于对膜材料性能的不了解及理论分析中所采用的本构关系太过近似所致.因此准确把握膜材料的力学性能对于膜结构的研究、应用和推广至关重要.本文对几种常见的建筑膜材料进行了一系列的试验研究,包括单轴性能试验、双轴性能试验、粘弹性性能试验、温度试验等,对建筑膜材料的抗拉强度、拉伸曲面进行了系统研究,考虑了温度对于膜材料力学性能的影响,并采用几种常见的粘弹性模型对膜材料的粘弹性性能进行了预测,最后提出了下一步的研究方向.     

Several Geotechnical Design and Construction Issues with Akashi Strait Bridge

The Akashi Kaikyo (Strait) Bridge, one of the major bridges of the Honshu-Shikoku bridge network connecting the main island and the Shikoku island, is the world's longest suspension bridge with a center span of about 2,000 m. The bridge was constructed over the Akashi Strait and opened to traffic in 1998 after a construction period of about 10 years. The granite stratum in the Akashi Strait was very deep, while the granite stratum provides the foundations for the other long span bridges which have been constructed in Japan. Three of the four foundations had to be constructed on either a weakly cemented gravelly soil deposit or a sedimentary soft rock layer. The geological structure was carefully investigated and the geotechnical properties, in particular the strength and deformation characteristics of these geomaterial types, were carefully evaluated. To this end, a comprehensive series of advanced triaxial compression (TC) tests were performed on rotary core tube samples of sedimentary soft rock after it was found that the due design was not possible based on unconfined compression tests. Both CD and CU TC tests and cyclic undrained triaxial tests were performed on rotary core tube samples (30 cm in dia.) of the gravelly soil. Based on the data, the long-term and seismic stabilities of the foundations were evaluated. The importance of strain- and pressure-dependent nonlinear stress-strain behaviour at small strains, as well as accurate strain measurements in the laboratory stress-strain tests, was confirmed by analyzing the full-scale behaviour of the foundation during and after construction and comparing the back-calculated stiffness values with those obtained from laboratory stress-strain tests, pressure-meter tests, plate loading tests and field shear wave velocity measurements.