【作者】 尹华泉；

【导师】 刘沐宇； 丁庆军；

【作者基本信息】 武汉理工大学 ， 桥梁与隧道工程， 2006， 硕士

【摘要】 轻集料混凝土(Lightweight Aggregate Concrete,简称LWAC)具有轻质、高强、抗震性、耐久性好的特点,而高强轻集料混凝土(High-strength Lightweight Aggregate Concrete,简称HLWAC)具有更广的应用前景。次轻集料混凝土也如此(Specified Density Concrete,简称SDC)。在桥梁的桥面铺装层和上部承重结构中采用HLWAC,能大大减轻桥梁自重、增大跨距、提高抗震性能,因此高强轻集料混凝土是今后大跨桥梁优选的建筑材料之一。但是,其力学性能研究仍然存在一些急需解决的问题,如轻集料混凝土弹性模量相对较低、脆性大。因此,对高强轻集料钢筋混凝土梁的抗剪性能进行试验研究,将是一项具有重要的理论意义和现实意义的课题。 在工程中应用强度高达60MPa的高强轻集料混凝土在一些发达国家已经普遍,而目前国内只对强度较低的轻集料混凝土构件的力学性能作过研究,对强度为60MPa甚至更高的高强轻集料混凝土的结构及力学性能研究尚未进行,而抗剪问题便是其中之一。因此,本文在分析现有国内外有关轻集料资料的基础上,研究了在有、无腹筋的情况下高强轻集料以及次轻集料钢筋混凝土梁抗剪性能,分析了混凝土强度、配箍率、剪跨比对构件抗剪强度的影响,并在分析本次试验和国内外相关试验研究的基础上,提出了高强轻集料混凝土梁斜截面抗剪极限承载力的计算公式,为高强轻集料及次轻集料混凝土的研究提供了试验依据。论文的主要内容按章节先后包括以下几个方面: 1.简述了轻集料混凝土的特点和目前国内外在桥梁工程中的应用概况,分析了有关轻集料混凝土力学性能的理论研究现状,列举了我国对轻集料混凝土的研究所取得的成果以及不足,在总结当前轻集料混凝土存在问题的基础上,提出了本文研究的主要内容和目标。 2.介绍了试验概况,包括试件的设计与制作、材料的性能指标、试验的前期工作、试验方案和加载与测量等内容。 3.通过对16根试验梁的抗剪试验,分析了高强轻集料混凝土梁(以下简称LC梁)及次轻集料混凝土梁(以下简称SC梁)的抗剪承载力,研究了剪跨比、混凝土强度、配箍率对抗剪承载力、抗剪承载力特征值、混凝土抗剪强度的影响。试验研究表明:LC及SC梁的抗剪承载力随混凝土强度、配箍率的提更多还原

【Abstract】 Because LWAC has light-weight, high strength, good earthquake resistant performance, high durability and remarkable economic benefits characteristic, and HLWAC has more wide prospect of application on bridge engineering.So does Specified Density Concrete (SDC). Using HLWAC in the bridge upper structural can reduce the deadweight of bridge, increase the span and enhance aseismatic characteristic which bringing the huge economic benefit. So, HLWAC is one of the most desired concrete as a construction material in long-span bridge construction. But its mechanics performance studying about some problems imminently need to be solved, such as the lower elastic model, more brittle and so on. So it is necessary to study the shear capacity of reinforced high-strength lightweight concrete beams, which has the important theories and realistic meaning.In developed country, HLWAC (fcu≥60MPa) has been widely used in structural applications. But in China at present, investigations of the mechanic character of HLWAC are practically almost rare, only on low strength LWAC. The shear resistance of HLWAC is one of the problems.So, on the base of analysis of current bridge reinforcement, makes a relative system experiment research and theory analysis for the shear capacity of reinforced HLWAC beams. The objectives of this investigation are to study the shear behavior of beams, analyze the effect of different parameter on shear strength of all beams, and propose a simplified and reasonable formula to calculate the shear resistance of reinforced HLWAC beams, which provide some theory support for studying HLWAC and SDC. According to the chapter order of this thesis, this paper contains such research result as following:1. Describe LWAC advantages and its state on bridge engineering in the world, and analyze current situation of theory study on LWAC mechanical characteristic and list existing some problems of present LWAC study. On the basis of them, main emphasis and goal of this text are put forward.2. This paper introduces general situation of the test, including designing and casting the beams, material performances, previous work, testing program, loading and measuring etc.3. Through the tests of 16 specimens with and without web bars, the effect of concrete strength, stirrup ratio and shear span ratio on shear strength, shear resistance eigenvalue, and concrete shear resistance eigenvalue were researched.The experimental results indicated that the ultimate shear strength of LC and SC beams with and without stirrups increases with the increase of concrete strength and stirrup ratio. At the same shear-span ratio, the ultimate shear resistance of LC beams is lower than SC and NC beam.The ultimate shear strength of beams with and without stirrups increases with the increase of concrete strength. Correspondingly, the range of concrete strength increases, the shear strength eigenvalue decreases. When shear-span ratio is bigger, the contribution of concrete to shear capacity exhibits a post-peak behavior. This indicates that concrete continues to contribute after exhibiting the maximum shear capacity. Shear strength of concrete decreases with the increase of shear-span ratio, concrete strength and stirrup ratio.4. Analyze longitudinal reinforcement and the web reinforcement strain of different section of specimen beams, and analyze the web reinforcement strain of LC and SC beams comparatively. Research the effect of different parameter on LC and SC beams’ deflection, and the diagonal crack propagation and failure mode. The experimental results indicated that the stirrups had no effect on the diagonal cracking load, but play an important role in the shear capacity of beams after cracking. Stirrup strains measured during testing were negligible up to the diagonal cracking load, moreover, the stirrups closed to the supports and load points were under compressive state. Stirrup strains were lager at mid section, but smaller at two sides. Deflection of all beams increases with the increase of shea-span ratio, but concrete strength and stirrup ratio do little to the deflection of beams. In the same situation, deflection of LC beams is larger than SC beams’. Reinforced HLWAC beam has the same failure mode as the normal-weight concrete beam. Shear failure is more abrupt and failure surfaces are smoother for high-strength LC beam.But, for SC beams, the cracks are flexuose with lots of rubble exiting between cracks.5. Based on present code JGJ12-99, recursivea analyse was conducted to the test data of this test and foreign scholar. Propose a simplified and reasonable formula is proposed to calculate the shear resistance of reinforced high-strength lightweightconcrete beams,Furthermore, the conditions of upper and lower limit for using the formula are given in this thesis.The results indicate that the test datas and calculationvalue is close perfectly.The study of the shear capacity of reinforced HLWAC and SDC beams is one comprehensive research field. There are more relevant disciplines involved, it is relatively great to study the degree of difficulty. But it is extensive that its project uses the prospect, social effects and economic effects are enormous. It is a new field that the study of the shear capacity of reinforced HLWAC and SDC beams, there are few studies at present. According the test of shear capacity of reinforced HLWAC and SDC beams with and without web reinforcement, this thesis provides a lot of contributing data and has made some achievements. A simplified and reasonable formula and the conditions of upper and lower limit for using it are proposed. The urgent need used with the deepening and project of the theoretical research, the research of this field will be deepened further.更多还原