体外预应力法在工程中的应用研究

发布时间：2018-08-18 19:58

【摘要】：体外预应力是后张预应力体系的重要分支之一,它主要应用在建筑工程加固改造和桥梁工程中,体外预应力技术是将预应力筋布置于结构构件之外,对预应力筋施加体外预应力的一种方法,其加固实质就是用高强钢筋、钢绞线或高强钢丝等作为材料,通过张拉预应力筋和设置转向装置对结构或构件施加体外预应力,来抵消外荷载产生的部分内力,从而改善混凝土梁的使用性能和提高其极限承载能力、抗裂性及抗变形能力。国内外学者对体外预应力混凝土结构进行了大量的科研性疲劳性能方面的研究,但对体外预应力混凝土结构进行验证性疲劳性能方面的研究尚属少例。本文以吉林省石油化工设计研究院—嘉吉生化有限公司变性淀粉改造项目（变性淀粉车间）为背景,把实际工程中加固的连续梁简化为简支梁来模拟实际工作效果,进行体外预应力加固混凝土梁的验证疲劳试验及静载试验,记录了试验梁的承载能力、挠度、钢绞线、钢筋和混凝土的应变以及裂缝发展情况等进行了详细分析;并进行疲劳验算和极限承载力验算,满足现行规范要求。进而验证体外预应力法的实际加固效果。体外预应力梁的试验研究和理论分析结果表明,体外预应力梁在经历82万次的疲劳荷载作用下,转向块、锚固系统工作性能良好,没有失效,说明体外预应力加固的混凝土梁抗疲劳性能良好,能够满足实际工程的生产要求。为设计院今后进行此类工程项目加固工作以及采用体外预应力加固技术,积累经验,提供了实际工程参考价值,并具有一定的实际意义。基于本文的试验结果,对今后设计院采用此法加固实际工程及进行类似的疲劳试验时给出以下主要建议:(1)转向块应至少采用Q345级钢材;(2)梁端的锚固钢板,不宜出现悬臂段,应完全锚固在钢筋混凝土梁的两端或柱子上;(3)试验中构件若采用T型截面梁,并采用两点或多点加载方式会更接近实际工程,试验结果误差会更小。
[Abstract]:External prestressing is one of the important branches of post-tensioned prestressing system. It is mainly used in the reinforcement and reconstruction of building engineering and bridge engineering. External prestressing technology is a method of arranging prestressed tendons outside structural members and applying external prestressing to prestressed tendons. The essence of strengthening is to use high-strength steel bars, strands or high-strength steel. External prestressing is applied to the structure or component by means of tensioning tendons and setting steering devices to counteract some internal forces generated by external loads, so as to improve the serviceability of concrete beams and enhance their ultimate bearing capacity, crack resistance and deformation resistance. There are a lot of research on fatigue properties of scientific research, but there are few studies on verifying fatigue properties of externally prestressed concrete structures. This paper takes the modified starch modification project of Jilin Petrochemical Design and Research Institute-Jiaji Biochemical Co., Ltd. (modified starch workshop) as the background, and strengthens the continuous beam in the actual project. Simplified as simple-supported beam to simulate the actual work effect, carried out the verification fatigue test and static load test of external prestressing reinforced concrete beams, recorded the load-bearing capacity, deflection, strand, steel and concrete strain and crack development of the test beams in detail; and carried out fatigue checking calculation and ultimate bearing capacity checking calculation, full The experimental and theoretical analysis results show that under 820 000 fatigue loads, the steering block and the anchorage system have good working performance and no failure, indicating that the concrete beams strengthened by external prestressing have good fatigue resistance. It can meet the production requirement of practical project and provide reference value for the design institute to reinforce this kind of project and adopt external prestressing reinforcement technology in the future. The following main suggestions are given in engineering and similar fatigue tests: (1) steering blocks should be made of Q345 steel at least; (2) anchored steel plates at the end of beams should not be cantilevered, and should be completely anchored at both ends or columns of reinforced concrete beams; (3) members with T-shaped cross-section beams and two or more points of loading will be closer in the test. In actual engineering, the error of test result will be smaller.
【学位授予单位】：长春工程学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU746.3;TU757.1

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