混杂纤维提高混凝土梁以及组合梁特性的成果分析 硕士毕业论文.docVIP

摘 要 随着现代建筑向高层化、大跨度、重载荷及轻量化方向发展，混凝土这一最大宗的建筑材料正朝高韧性、高阻裂、高体积稳定性和高耐久性等高性能方向发展，其中又以改善混凝土的韧性、提高其抗裂性能为当前发展高性能混凝土的技术核心。 纤维增强混凝土是一种多相材料，其在土木工程中的应用日益广泛。在混凝土中掺入纤维能够从微观机制上改善材料的性能提高混凝土的抗拉强度、韧性、延性、抗裂性及抗冲击疲劳等性能。 混杂式钢纤维增强混凝土梁的结构，它是在经济与性能并重的基础上，使钢纤维分层布置，即钢纤维分布于混凝土梁的上部和下部，形成“层布式钢纤维增强混凝土”。为解决其中间部分素混凝土的韧性、抗裂性及抗渗性均较差这一问题，我们在混凝土基体中全体积掺入PVA或者聚丙烯纤维，使之与上下层钢纤维共同作用发挥“正混杂效应”来改善混凝土的性能。 本文通过对已有的研究成果分析例如层布式钢纤维与混掺PVA纤维混凝土梁的力学性能试验、层布式钢纤维——聚丙烯腈纤维混凝土力学性能试验研究、混杂纤维布加固钢／聚丙烯短纤维增强混凝土构件技术研究、混杂纤维材料加固混凝土梁刚度的试验研究以及高强混凝土组合梁的研究，我们可以得出混杂纤维混凝土改善了混凝土的的性能，混杂纤维的混杂效用提高了混凝土的承载力、延性、刚度、极限应变等，并且给出了混杂纤维混凝土组合梁的承载力、裂缝的计算分析，从而我们可以将混杂纤维应用于组合梁中，为提高组合梁边缘混凝土的极限应变值以及混凝土的特性提供了理论依据。 关键词：混杂纤维，层布式钢纤维混凝土，组合梁，承载力 ABSTRACT With the building becoming high,long span,heavy load and lightweight,cement concretewhich is widly used material has developed to high toughness,high,high Volume stability and high durability,and how to improve the toughness and the cracking-resistance is key technology. Fiber reinforced concrete is a kind of hererogeneous material,which is more increasingly used in civil engineering.The incorporation of steel or other fibers in concrete can significantly improve the performance of cementitious materials,such as tensile strength,toughness,and ductility as well as resistance to crack and fatigue. Layer steel Fiber Reinforced Concrete(LSFRC),which is on the basis of considering economy and improvement of material properties,letting steel fiber layer distributing layer by layer,and steel fibers are scattered to the upper and lower layer,concrete which is cast by this method,is called LSFRC.For the disadvantage of inferior toughness,crack resistance and infiltration resistance of the middle layer,polypropylene fibber are mixed entirely in the concrete,For the purpose of exerting the “positive intermixing effect”to improve the performance of the concret. This paper describes layered steel fiber and blended PVA fiber mechanical properties of concrete beams, layered steel fiber - mechanical properties of Polyacrylonitril