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为了研究钢管混凝土柱在低周反复荷载作用下组合材料横截面刚度对其性能的影响,以果园港二期工程上的钢管混凝土柱为原型,对3根钢管混凝土柱进行低周反复加载试验。通过控制试件钢管厚度进行物理模型试验,研究钢管厚度对钢管混凝土柱耗能性能、承载性能、强度退化、刚度退化、延性和变形能力的影响。试验结果表明:随着试件钢管厚度的增加,试件的能量耗散系数与等效黏滞阻尼系数均随之减小,试件的耗能能力随之变弱;钢管厚度越小,钢管混凝土柱试件的耗能性能越好。钢管越厚,对核心混凝土的约束作用就越强,强度退化就越弱,试件塑性变形能力就越好。钢管越厚,外包钢管对核心混凝土约束作用就越强,水平承载能力越高。 相似文献
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The interfacial bonding performance between seawater sand concrete and basalt fiber reinforced polymer (BFRP) bars were tested under different textile reinforced concrete (TRC) confinement layers, confinement sequences and chloride salt dry-wet cycles. The results show that TRC confinement can change the failure mode of the specimen and improve the ductility of specimens. With the increase of corrosion age, compared with the specimens with the same restrained layers in the conventional environment, the ultimate bond strength of restrained specimens before corrosion gradually decreases, and the slip value when reaching the ultimate bond strength also slightly decreases. The bond strength of the pre-restrained corroded specimens has the same development trend. Based on the bond-slip model of deformed steel bars and concrete proposed by Eligehansen for the first time in 1983—BPE model, under the control of TRC confinement and corrosion age, the relationship between the TRC confinement layer and the ultimate bond strength and slip of seawater sand concrete and BFRP steel bar is established. By fitting and predicting the ultimate bond strength, corresponding slip value, and corrosion age control of different TRC confinement layers, it is found that the confinement effect will not be significantly improved when the confinement layers exceed 4 layers. Under long-term chloride corrosion, the failure mode of the specimen may still change into splitting failure when the number of restrained layers is small. 相似文献
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Hollow concrete columns (HCCs) constitute a structurally efficient construction system for marine and offshore structures, including bridge piers and piles. Conventionally, HCCs reinforced with steel bars are vulnerable to corrosion and can lose functionality as a result, especially in harsh environments. Moreover, HCCs are subjected to brittle failure behavior by concrete crushing due to the absence of the concrete core. Therefore, this study investigated the use of glass fiber-reinforced polymer (GFRP) bars as a solution for corrosion and the use of hollow composite-reinforced sections (HCRSs) to confine the inner concrete wall in HCCs. Furthermore, this study conducted an in-depth assessment of the effect of the reinforcement configuration and reinforcement ratio on the axial performance of HCCs. Eight HCCs with the same lateral-reinforcement configuration were prepared and tested under monotonic loading until failure. The column design included a column without any longitudinal reinforcement, one reinforced longitudinally with an HCRS, one reinforced longitudinally with GFRP bars, three reinforced with HCRSs and different amounts of GFRP bars (4, 6, and 8 bars), and three reinforced with HCRSs and different diameters of GFRP bars (13, 16, 19 mm). The test results show that longitudinal reinforcement—whether GFRP bars or HCRSs—significantly enhanced the strength and displacement capacities of the HCCs. Increasing the amount of GFRP bars was more effective than increasing the bar diameter in increasing the confined strength and the displacement capacity. The axial-load capacity of the GFRP/HCRS-reinforced HCCs could be accurately estimated by calculating the load contribution of the longitudinal reinforcement, considering the axial strain at the concrete peak strength. A new confinement model considering the combined effect of the longitudinal and transverse reinforcement in the lateral confinement process was also developed. 相似文献
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This paper provides novel results and key findings for the bond-slip field since there is no single study available in the literature conducted on the bond-slip behaviour of concrete filled double skin steel tubular (CFDST) columns. Likewise, no studies have been focused on the contribution of welded reinforcing bars on the bond behaviour of composite columns. A series of push-out tests on sixteen specimens of CFDST columns are presented to explore the bond-slip behaviour between the cross-sectional elements (the inner steel tube, outer steel tube and the shell concrete). The primary test parameters involve (a) interface type (normal interface, interface with an internal ring, with reinforcing bars, and with shear studs); (b) concrete strength (high strength concrete and normal strength concrete); (c) push-out type (push-out of the shell concrete and push-out of the inner tube). The results demonstrated that greater benefits arose on the bond strength, once the reinforcing bars or internal rings were welded onto the inner steel tube of CFDST columns. Moreover, in addition to remarkably improving the bond strength, the welded reinforcement bars would significantly improve the compressive strength of CFDST columns and eliminate the local buckling of the inner steel tube. On the other hand, the embedded shear studs (bolts) onto inner steel tubes are capable of improving the bond strength with less degree of the shear resistance in comparison with the other interface types. What's more, the current paper is also adapted to explore the influence of concrete grade (normal and high strength) on the bond performance of CFDST columns and it is showed that the bond strength increases considerably as the strength of the shell concrete is increased. Finally, the bond improvement ratio (BIR) is studied which could be a representative index in comparing the performances of the parameters on the bond behaviour. 相似文献
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Existing rule scantling formulae of plate members are based on conventional plastic design theory, and do not necessarily reflect complicated plate bending phenomena under axial loads. In this study, we first formulated the effect of axial load on the fully plastic moment based on the von Mises yield criterion for longitudinally stiffened plate in addition to the well-known formula for transversely stiffened plate. In addition, we derived a theoretical formulation of the lateral pressure corresponding to 2-point hinge and 3-point hinge formation taking account of the effect of the additional lateral force due to the axial loads on the deflected plating, using a simple plate strip bending model assuming a long plate with a large aspect ratio.Then, a series of elastic-plastic FE analyses was carried out to verify the structural behavior and the effect of axial load on the plate plastic bending strength. The plate strength was evaluated based on the residual deflection criteria of two cases (0.26 mm and 4.0 mm), and the results were compared with the theoretical derivation. As a result, it was found that assumption of linear strength reduction to the axial stress can cover the transversely stiffened plate under compressive axial stress conservatively. As to the transversely stiffened plate under tensile axial stress and the longitudinally stiffened plate, the strength reduction was in accordance with the reduction in the fully plastic moment based on the von Mises yield criterion in the conservative side. Finally, based on the findings, the required plate thickness coefficients were proposed on an empirical basis both for transversely and longitudinally stiffened plate under compressive and tensile axial loads. 相似文献
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Effect of pitting corrosion on the ultimate strength of steel plates subjected to in-plane compression and bending 总被引:2,自引:0,他引:2
Tatsuro Nakai Hisao Matsushita Norio Yamamoto 《Journal of Marine Science and Technology》2006,11(1):52-64
Corrosion pits with a circular cone shape are typically observed on coated hold frames of aged bulk carriers which carry exclusively
coal and iron ore. In order to ensure the safety of these types of bulk carrier, it is necessary to understand the effect
of pitting corrosion on the local strength of hold frames. In order to investigate this effect, a series of nonlinear finite-element
(FE) analyses has been performed with pitted plates subjected to in-plane compressive loads and bending moments. It has been
shown that the ultimate compression load or bending moment of pitted plates is smaller than that of uniformly corroded plates
in terms of average thickness loss, and that predictions of the ultimate strength using the average thickness loss at the
minimum cross section would be conservative. In order to establish a method of evaluating strength reduction due to pitting
corrosion, it is important to identify the failure mode that would be most detrimentally affected by pitting corrosion. It
was found that the reduction of the ultimate compressive load or bending moment due to pitting corrosion is smaller than that
of the tensile strength in terms of equivalent thickness. 相似文献
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Proper material constitutive models for concrete-filled double skin tube (CFDST) columns with circular cross-section and subjected to axial compressive forces are proposed and verified against experiment data using the nonlinear finite element program Abaqus. It is shown that CFDST columns can provide a good confining effect for concrete core, especially when the diameter-to-thickness ratios of both the outer and the inner tubes are small. In addition, empirical equations are proposed to predict the lateral confining pressure of the concrete core for CFDST columns. Finally, the axial strengths of the CFDST columns calculated by the proposed formulations are compared with AISC formulations against the experimental data. It has been shown that the proposed formulations are better than the AISC formulations. 相似文献
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针对桥梁工程高墩施工中施工速度、平台作业空间、支架刚度及避免错台和施工安全等问题,结合石公庄高架墩柱施工中采用的翻模法施工技术,从工序安排、模板设计、钢筋、混凝土工程等方面进行了研究,解决了山区桥梁高墩施工中存在的难题。 相似文献
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This paper describes the application of finite element method (FEM) and the development of equations to predict the failure pressure of single corrosion affected pipes subjected to internal pressure and axial compressive stress. The finite element analysis (FEA) results were verified against full-scale burst tests and theoretical calculations. Material non-linearity, which allow for large strains and displacements, were considered. In addition, true UTS instead of engineering UTS was used to determine the point of failure. The pipes used in the FEA was modelled based on API 5L X52 modified steel with a length of 2000 mm, a nominal outer diameter of 300 mm, and a nominal wall thickness of 10 mm. The results obtained from FEA were compared to that of existing comprehensive corrosion assessment method, known as DNV-RP-F101. Six equations, utilizing the Buckingham's π theorem and multivariate non-linear regression techniques, were developed for predicting the failure pressure of corroded pipeline with single defect subjected to both internal pressure and axial compressive stress. These equations provide improved failure pressure predictions with good margins of errors (less than 10%). 相似文献
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Locally pitted tubular members are usually considered as stub columns to assess the ultimate strength. However, it is not suitable for those with relatively larger slenderness ratios as their failure behavior is more complex and closely related to corrosion features of localized pitting. This paper presents compressive column tests on locally pitted tubular members of a moderate slenderness ratio. Corrosion pits were artificially introduced on local surface of the members, forming corrosion patches with various corrosion features. A numerical modelling method was proposed to reproduce the test specimens. Localized pitting damage was proven to cause substantial declines in the load deformation capacity and ultimate strength, and have a significant effect on the failure mode. The failure of a pitted member is mostly initiated by local buckling after yielding occurs in the corrosion patch, concurrent with pitting closure, and even shear cracking of member wall due to the perforated pits. Moreover, shape change of the corrosion patch most likely results in the failure mode to alter from column buckling to local buckling or interactive buckling. The shape ratio of the corrosion patch is one of the critical factor to influence the ultimate strength of locally pitted members. The proposed modelling method is applicable for extensive stochastic simulations so as to develop an empirical formula and to clarify the probabilistic characteristics of ultimate strength. 相似文献
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通过对钢纤维砼试验分析,探讨出满足施工要求的钢纤维砼配合比;通过室内试验与室外施工比较,钢纤维砼比普通砼在抗压、抗折、抗渗、抗弯等方面均有较大提高,应用于桥面铺装,提高了桥面的强度和耐久性。 相似文献
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船舶在冰区航行时,将遭受浮冰的挤压,船舷侧部位的加筋板会受到冰载荷的作用。以单筋单跨加筋板为研究对象,采用非线性有限元法对冰载荷下加筋板轴向压缩极限强度进行分析。研究冰载荷的大小、加载区域面积和加载区域位置的不同对极限强度的影响规律。结果表明,冰载荷大小一定,冰载荷作用区域面积逐渐增加时,加筋板的轴向压缩极限强度随着面积的增加基本呈线性增加。冰载荷作用区域位置距离加筋板中心点距离逐渐增加时,加筋板的轴向压缩极限强度逐渐增加,且随着相对距离的增加,对加筋板轴向压缩极限强度的影响越来越大。这些结果可用于指导冰区船舶结构的设计以及维护。 相似文献
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天津某码头工程拟采用预应力混凝土方桩进行码头施工建设.在前期的勘察过程中研究确定单桩轴向极限承载力,对后续工程的设计、施工工作至关重要.现场勘察项目部在本工程的前期勘察工作中组织安排了单桩静载试验,同时依据有关规范使用地区经验值进行单桩轴向承载力估算工作.基于工程实例,对拟采用的预应力混凝土方桩,运用规范经验法与试桩静... 相似文献
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The present paper addresses the stresses in dynamic steel tube umbilicals at the platform hang-off exposed to large motions corresponding to an extreme storm condition. Experimental tests were carried out by mounting fibre-optic Braggs inside steel tubes of a 9 m long umbilical specimen. Then the specimen was exposed to constant tension and dynamic curvature by means of a bellmouth and the stresses were measured. Realizing that the geometry of the umbilical cross section was too complex to apply full 3D modeling, a beam and penalty contact modeling procedure was applied to describe the extreme stress behavior. Then a simplified method was proposed to determine the contact stiffness which was further validated by full scale umbilical axial stiffness testing. As hoop contact interfaces between steel tubes and separation fillers were observed in the test specimen, a tailor-made contact element was formulated to facilitate hoop contact. Different modeling alternatives were used to investigate the hoop contact effect on the extreme axial stress and Coulomb friction stress range, which were further validated against measured dynamic axial stress. Good correlation was found by the combination of describing all contact interfaces and constraints due to the grooves in the inner sheath. 相似文献