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Q460GJ钢焊接H型钢梁整体稳定性能研究
中文摘要

近年来,国内外大量的建筑及桥梁结构由于采用了高强度钢结构,取得了很好的经济效益,针对高强钢结构性能的各项研究工作业已展开,已有的研究成果表明:高强度钢结构构件的整体稳定性能优于普通强度钢结构构件;高性能建筑用钢板(简称高建钢)和普通低合金高强钢相比,具有更好的综合性能,众多高层和大跨结构中全部或在重要部位中使用了高建钢;我国《钢结构设计规范》(报批稿)将适用范围提高到了Q460,并增列了高建钢系列中的Q345GJ钢,但相关条文多是在对普通强度钢结构的研究基础上提出的,由于材料性能的不同,这些条文是否适用于高性能高强钢结构,尚需进一步研究;国内对高建钢结构构件的研究工作已有时日,但针对高强度高建钢受弯构件整体稳定性能的研究工作却刚刚起步。本文依托国家自然科学基金面上项目《460MPa高强度GJ钢基于性能的计算模式研究》(基金号:51578089),通过试验研究、数值计算和理论分析,研究Q460GJ钢焊接H型钢梁的整体稳定的受力性能,并提出计算方法建议。本文主要研究工作如下: ①采用切条法对8个Q460GJ钢焊接H形构件的残余应力进行了测试,讨论了构件高宽比、构件高度、板件宽厚比、板件厚度等因素对残余应力分布的影响,提出了适用于Q460GJ钢中厚板焊接H形构件残余应力的分布模式。 ②系统分析了支座和加载点约束条件对受弯构件整体稳定承载力的影响,提出了用于跨中无侧向约束和有侧向约束两种条件下,简支钢梁在跨中单点加载时整体稳定承载力的试验方法并开发了相应试验装置;推导了考虑偶联时监测点处竖向及侧向位移、截面转角的计算公式。 ③对16个无侧向约束的Q460GJ钢焊接H型钢梁(8个双轴对称截面、8个单轴对称截面)和14个有侧向约束的Q460GJ钢焊接H型钢梁(8个双轴对称截面、6个单轴对称截面)进行静力加载试验,研究了其失稳形式和极限承载力。 ④对构件进行有限元分析,研究了初始几何缺陷、残余应力对Q460GJ钢梁整体稳定性能的影响,并将试验结果和有限元分析结果与国内外钢结构设计规范的计算曲线进行比对,指出《钢结构设计规范》(GB50017-201X)(报批稿)关于梁整体稳定的计算方法适用于Q460GJ钢中厚板焊接H型钢梁。 ⑤获得了按GB50017-201X规范推荐的方法计算Q460GJ钢焊接H型钢梁整体稳定时的抗力不定性统计参数;按《建筑结构可靠性设计统一标准》 (GB50068-201X)(报批稿)的规定,计算了Q460GJ钢中厚板梁在各种荷载组合下的抗力分项系数,统计分析后给出了抗力分项系数和设计强度建议值。 关键词:Q460GJ钢,残余应力,整体稳定,试验研究,设计方法

英文摘要

High-strength structural steel has been widely used in building structures and bridges all over the world, in which good benefits have been achieved. Relevant experimental and numerical study has been carried out. Available results demonstrate that high-strength steel members exhibit superior global stability to conventional steel members. High-performance structural steel plates, GJ steel for short, have better total performance as compared with conventional low-alloy high-strength steel, and thus it has been applied to critical parts or the whole of many high-rise or large-span structures. The draft version of Code for Design of Steel Structures in our country has extended its scope of application to Q460 grade steel and also incorporated Q345GJ steel in it. Nevertheless, the associated design provisions are proposed based on the study of conventional structural steel, which hinders the full use of the advantages of high-strength and high-performance steel. To date, investigations on GJ steel have been conducted for many years, whereas the study on the global stability behaviour of high-strength GJ steel flexural members has just started. Supported by the research grant entitled "Performance-based calculation model study on 460 MPa high strength GJ steel" (No. 51578089) from the National Natural Science Foundation, the thesis intends to conduct experimental tests, numerical simulations and theoretical analyses on the global buckling behaviour of welded H-shaped Q460GJ steel beams and to recommend design methods. The following aspects have been completed in the study. ①Residual stresses in eight welded Q460GJ H-sections was measured by using sectioning method, and the effects of height-width ratio, section height, width-thickness ratio and thickness of steel plates on residual stress distribution were discussed. A model for residual stress distribution in H-sections welded by Q460GJ heavy plates was proposed. ②The effects of supports and restraints at the loading point on the global buckling resistance of flexural members were analyzed systematically. A new testing method and the corresponding testing setup were developed to overcome the major limitation of previous studies, which could be used for quantifying the global buckling resistance of simply-supported beams loaded by a point load at the mid-span with or without lateral restraints. Moreover, formulae considering the coupling effect were derived for calculating the vertical and lateral displacements and the rotation of beam section at the measuring point. ③By using the patented test setup developed by the research group, experimental tests were carried out on 16 laterally-unrestrained welded Q460GJ H-sections (with 8 doubly-symmetric sections and 8 singly-symmetric sections) and 14 laterally-unrestrained welded Q460GJ H-sections (with 8 doubly-symmetric sections and 6 singly-symmetric sections), to investigate the ultimate load resistance and failure mode. ④Numerical simulations were conducted for welded Q460GJ H-beams, through which the influence of initial geometric imperfections, residual stresses on the global buckling resistance of Q460GJ steel beams was studied. Comparisons between numerical results and calculated values from various design codes suggested that the design method incorporated in the draft version of Code for Design of Steel Structures (GB50017-201X) could be used for determining the global buckling resistance of welded Q460GJ H-sections with good accuracy. ⑤The statistical parameters for the uncertainty of calculation mode was obtained when the global buckling resistance of welded Q460GJ H-sections was calculated in accordance with the recommended method in GB50017-201X. Based on the requirements specified in Unified Standard for Reliability Design of Building Structures (GB50068-201X) (draft version), partial safety factors for the global buckling resistance of beams made of Q460GJ steel heavy plates were calculated under various combinations of loads, and finally the recommended values of the partial safety factor and the design strength were proposed after statistical analyses. Keywords: Q460GJ steel, Residual stress, Global buckling, Experimental test, Design method

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