来源：高强轻集料混凝土构件优化设计与性能研究 发布时间：2010年7月29日
结构轻集料混凝土具有轻质、抗震性好、耐久性高的特点，特别适用于高层建筑、桥梁等大跨度结构工程，以及地质条件复杂和对材料耐久性有特殊要求的重点工程建设，并对各种工程具有广泛意义，其应用前景非常广阔。本论文在对高强轻集料混凝土制备技术与基本材性的研究基础之上，采用试验、有限元模拟与工程应用相结合的研究方法对钢筋及预应力高强轻集料混凝土构件性能进行了深入、系统的研究，揭示了材料与构件之间的相关性，提出轻集料混凝土构件优化设计方法。研究成果为修订《轻集料混凝土结构设计规范》与编制《轻集料混凝土桥梁设计规范》提供了重要的参考，对于促进该类材料广泛用于桥梁结构意义重大。 本文进行的主要工作和取得的重要成果有： 探明了影响高强轻集料混凝土物理力学性能的主要因素，确定了制备LC40～LC60高强轻集料混凝土的关键技术参数，利用800级高强轻集料与42.5级普通硅酸盐水泥为主要原料制备出具有高工作性能、高性价比的LC40～LC60轻集料混凝土；回归出LC40～LC60高强轻集料混凝土应力—应变关系数学表达式，为结构设计与有限元分析奠定了理论基础。 系统研究了LC40～LC60钢筋轻集料混凝土抗弯构件的性能，研究了钢筋轻集料混凝土构件的正截面承载力、延性、开裂荷载以及破坏特征，验证了普通混凝土结构设计规范公式对于高强轻集料混凝土的适用性，修正了矩形截面梁开裂弯矩计算公式。 结合依托工程，设计制作一片20m预应力高强轻集料混凝土实体梁，研究了预应力构件的荷载、挠度、混凝土变形之间关系；利用ANSYS有限元分析软件与计算机技术，建立了有效、适用的预应力轻质混凝土结构有限元模型；利用该模型模拟研究了构件在预应力和荷载作用下的力学行为，以及端部锚固区混凝土应力分布特征，探明了预应力构件端部锚固区混凝土开裂的原因，提出了能够有效解决预应力轻集料混凝土构件端部开裂问题的结构梯度设计方法，确定了构件端部结构与材料最优参数。 深入研究了预应力轻集料混凝土构件的长期徐变效应。探明了LC40轻集料混凝土的徐变特性，回归出14d龄期预应力张拉的轻集料混凝土徐变系数公式，推导出有限元分析蠕变准则系数C_1值的计算式，为利用有限元模型分析构件的长期徐变效应奠定了基础；模拟研究了构件分别在裸梁状态与使用荷载作用状态下的预应力损失及挠度变化规律，比较了轻集料混凝土与普通混凝土构件长期徐变效应。【Abstract】 Low density, good resistance to vibration and high durability are the characteristics of structural lightweight aggregate concretes (SLC) which are especially suitable for the construction of long-span structural projects such as high buildings, bridges and key projects with complicated geography or a special command for durability. The priorities of SLC are significant to different project construction and will show wide prosperity. Based on the research of prepared technology and properties of materials, the properties of reinforced and pre-stressed high strength lightweight aggregate concrete was studied deeply and systematically with the method of experiment、finite element simulating and project application. Relativity of material and concrete member was revealed. The design method of optimizing for lightweight aggregate concrete member was proposed. Research results provide references for the amending of Design Criterion of Structural Lightweight Aggregate Concrete and the edition of Design Criterion for Lightweight Aggregate Concrete Bridge, and is of significant importance for the application of these materials in bridgestructure.The main research work and compliments of this paper are as follows:Main factors influencing the mechanic properties of high strength lightweight aggregate concrete (HSLC) was found out. Key technical parameters for preparing HSLC with the strength range of LC40～LC60 were confirmed. Lightweight aggregate concretes of LC40～LC60 with high workability were prepared with raw materials of high strength lightweight aggregate of class 800 and 42.5# Portland cement. Formula of constitutive relations model of HSLC was revised, which established theoretic foundation for structural design and finite element analysis.Properties of reinforced lightweight aggregate concrete (RLC) bending members with strength in the range LC40～LC60 were systematically studied for the first time. Bearing capacity of normal cross section, ductility, cracking load and failure characteristics of RLC were studied. The study result suggest that it is applicable of structural design criterion formula of common concrete for HSLC and then calculate formula for crack bending moment of rectangle cross section was revised.With supported project and one piece pre-stressed HSLC girder of 20m long, relations among load、deflection and distortion of pre-stressed members were studied; As a result, a effective and applicable finite element analysis model of pre-stressed lightweight aggregate concrete (PLC) was established using computer technology and ANSYS finite element soft. With using of the model, mechanic behavior of members under the action of pre-stress and load were researched, and the stress distribution characteristics of anchorage zone of concrete end was studied. The cracking causation of anchorage zone of concrete end was found out. Then, structural grads designing method for effectively resolving the cracking of anchorage zone of PLC end was invested. As a result, optimized parameters for member end structure and material were confirmed.Long-term creep effect of PLC member was studied for the first time. Creep characteristics of lightweight aggregate concrete with strength class 40 was founded out, then creep coefficient formula of LC under tendon pre-stress 14d age was regressed and calculating formula for the value of ruling coefficient C_1 in the finite element analysis was deducted, which established bases for the finite element analysis of long-term creep effect of members; Laws of pre-stress loss and deflection changing of members under the state of load and unload was studied and compared LC