【作者】 杨隆宇；

【导师】 李正良；

【作者基本信息】 重庆大学 ， 土木工程， 2011， 博士

【摘要】 随着特高压工程的推进,使用传统钢材的单角钢塔已无法满足使用要求。现有单角钢塔进行加强时为了施工方便,经常采用在原主材上增加一根同规格角钢组成双角钢十字截面构件的方式。目前双角钢十字截面构件在设计上主要是按照实腹式构件进行设计,在真型塔和实际使用中发现现行的设计与构件实际承载力和破坏方式有差别,国内外相关规范和规程也没有对这种截面形式和连接方式的构件作出详细规定,且存在一些不甚合理的内容。鉴于实践中遇到的问题和目前国内相关理论和试验研究还较少,对双角钢十字截面构件进行深入研究,具体工作体现在如下几方面:(1)采用L160×12、L160×14、L160×16三种截面规格角钢的Q420双角钢十字截面构件进行轴心受压和偏心受压试验共26个,确定十字截面构件失稳破坏模式并与现有设计方法对比。使用有限元方法得到多种截面规格、边界条件和λ构件稳定系数,验证现行规范对双角钢构件适用性并得到单节间构件轴心受压和偏心受压柱子曲线、长细比修正系数。通过对弹性模量折减系数的计算得到构件的局部稳定限值计算式。(2)采用L160×14角钢的Q420双角钢十字截面构件进行双节间轴心受压和偏心受压试验共12个,用有限元方法得到更多规格构件稳定系数,与试验结果分析比较后得到双节间构件轴心受压和偏心受压时的稳定系数以及长细比修正系数。(3)通过构件试验和有限元分析填板受力状态,对填板与构件承载力关系进行研究,明确对构件承载力有明显影响的填板参数。分析采用不同填板型式、间距对构件的影响,使用不同填板数量时对同截面各种λ下承载力影响大小,在此基础上得到双角钢十字截面构件填板设计公式。(4)通过对双节间试验横向支撑受力数据和有限元分析结果的对比,得到不同参数构件横向支撑内力与构件承载力变化规律,以及横向支撑长度对构件承载力和支撑内力的影响。在分析基础上得到横向支撑内力、构件荷载、横向支撑长细比、构件长细比之间的关系。(5)将双节间构件简化成中间设置弹性支承的简支梁后,在三弯矩方程基础上得到双节间构件弹塑性阶段承载力并与现有设计方法对比,根据二者随长细比的变化得到双节间构件承载力修正公式。更多还原

【Abstract】 For the development of State Grid and ultra-high voltage(UHV) projects in China, traditional latticed transmission tower could not meet the current demand, furthermore, adding another steel angle is a common way to mend and reinforce existent latticed tower for the simple reason that it is convenient in constructing . The generally accepted design technique treats such built-up cruciform section member formed by two equal-leg angles as a solid web cruciform section member, however, problems occur in full scale transmission tower tests and engineering applications. The test loads do not match with the design bearing capacity, and the failure mode of members is different from the design method. There is no detail design information in domestic and overseas codes for this kind of two equal-leg angle cruciform section member which could explain the different or guide the design. In consideration of the reasons mentioned above, a further research is made for built-up cruciform section member formed by two equal-leg angles, and the investigating work focuses on the following aspects:(1) Three different sectional dimension types of Q420(yield strength: 420MPa) steel single angle are used to form two equal-leg angle cruciform section member, which is L160×12, L160×14 and L160×16, respectively. The members are tested under axial and eccentric loading, and the total test number is 26. The unstable failure mode and failure mechanism are affirmed during the test and a comparison is made toward design method in current codes. A finite element analysis is conducted for more sectional dimension, boundary condition and slenderness ratio. Based on the experiment and finite element analysis, the applicability of nowadays codes is validated, column curves for single internode and double internode members are obtained, and the slenderness ratio correction factor for eccentric load test is calculated. A local stability limit value is gained through computing the reduction of elasticity modulus for single and double internode members.(2)The Q420(yield strength: 420MPa) steel single angles whose sectional dimension is L160×14 are used to run axial and eccentric load test, and the total test number is 12. Based on the finite element analysis of more sectional dimension and test results, stability coefficients and the slenderness ratio correction factor for double internode members are obtained.(3)The mechanism performance of filler plates is analysis by test results and finite element method. By the research on relationship between filler plates and members’ bearing capacities, the parameters which affluence the members’ bearing capacities remarkably are separated out. Different forms of filler plates and intervals are adopted in finite element analysis to find the relationship toward members’ bearing capacity, and the influence of filler plates arrangement with a series of members’ slenderness ration is test. Based on the test result and analysis, a filler plates design method is formed for two equal-leg angle cruciform section members.(4)Based on the comparison of experimental data and finite element analysis on lateral bracing in double internode members, the variation rule of lateral bracing axial force and member’s loading is obtained, and the influence of lateral bracing slenderness to member’s bearing capacity and lateral bracing axial force is found. A relational expression containing lateral bracing axial force, member’s loading, slenderness ratio of lateral bracing and members is given.(5)A simplification of double internode member is made which change the actual boundary condition to that of simply supported beam, and calculation equation is established based on the three-moment equation. The bearing capacity involving lateral bracing stiffness in elastic-plastic stage is computed. The calculation results are comparison with current design method, and bearing capacity modified formula is given for double internode members.更多还原