共查询到19条相似文献，搜索用时 109 毫秒
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为了减小后张法预应力张拉过程中预应力筋的实际伸长值与理论伸长值的误差,通过对理论计算和施工的各环节进行分析,得出了产生误差的原因,有针对性地提出了各种误差的控差和减差方案,对预应力施工技术有一定的指导作用和参考价值。 相似文献
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司海峰 《广西大学梧州分校学报》2002,(2)
本文介绍国内最小半径（R=40米）的预应力连续刚构梁的施工,通过1、技术准备——各类预应力筋伸长量的计算、各项预应力张拉顺序的确定;2、过程控制——施工工艺流程、预应力张拉过程监测;3、信息反馈——张拉数据复核、过程监测数据整理。全面介绍了这种特殊预应力混凝土结构的施工控制方法,对同类工程有较高的借鉴价值。 相似文献
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本文介绍国内最小半径(R=40米)的预应力连续刚构梁的施工,通过1、技术准备--各类预应力筋伸长量的计算、各项预应力张拉顺序的确定;2、过程控制--施工工艺流程、预应力张拉过程监测;3、信息反馈--张拉数据复核、过程监测数据整理.全面介绍了这种特殊预应力混凝土结构的施工控制方法,对同类工程有较高的借鉴价值. 相似文献
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吴宁 《彭城职业大学学报》1999,14(4):107-108
我们知道，为了能够准确测定钢筋混凝土构件的承载能力，就要首先准确的测定钢筋混凝土构件预应力值。而如何选用适当的拉伸机油压表，是确定钢筋混凝土构件预应力值正确与否的关键。也就是说，视预应力筋张拉力大小的不同，而应选用不同正确使用压力范围的油压表。即，正确的油压表选用方法是与设计张拉力相对应的油压表读数应落在该油压表测量上限的1／3－2／3区间范围内。 相似文献
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杨关锋 《杨凌职业技术学院学报》2008,7(3):18-20
钢绞线预应力混凝土在桥梁工程中已普遍使用,作为质量控制双控指标的钢绞线张拉伸长值及锚固张拉力的确定,是大梁张拉成功的关键。本文着重概述了预制大梁施工工艺及过程质量控制的主要环节,供从事钢绞线预应力张拉人员参考。 相似文献
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有粘结预应力FRP筋混凝土梁受弯有限元模拟 总被引：1，自引：0，他引：1
庄金平 《福建工程学院学报》2011,9(4)
采用有限元软件ABAQUS对预应力FRP筋混凝土梁受弯性能进行模拟。通过降温法施加预应力,忽略预应力筋与混凝土之间的粘结滑移。在收敛度差调整到3%、线性受拉损伤值dt的峰值取为0.9时,模拟结果与他人的试验结果比较基本吻合。 相似文献
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宗长江 《石家庄铁路工程职业技术学院学报》2013,(4):37-41
红柳河特大桥48m简支箱梁预应力质量控制的关键是节段箱梁预制过程中的预应力孔道位置控制和节段拼装过程中的湿接缝预应力孔道位置控制。由于48m箱梁节段拼装预应力筋过长、弯曲较多都会加大预应力筋的孔道摩阻损失,因此,后张法在张拉前测试预应力孔道的摩阻力是确保施工质量的有效措施。预应力孔道的摩阻测试有效验证了孔道位置施工质量,给预应力张拉提供准确的施工参数,确保预应力张拉施工质量。 相似文献
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姚梅红 《福建工程学院学报》2016,(6):518-525
通过对不同直径的抗拔灌注桩在不同抗拔荷载、不同裂缝控制等级下的抗裂设计及其纵筋用钢量与造价的对比分析,说明桩纵筋采用普通非预应力钢筋时,因受裂缝宽度的限制,其纵筋拉应力水平明显偏低,桩承受的抗拔力越大,纵筋的应力越小,相比普通钢筋混凝土桩,采用预应力螺纹钢筋的抗拔桩不仅可显著减少用钢量,当抗拔力较高时,还可节省约40%~50%的纵筋造价;同时进一步探讨抗拔桩预应力筋的配置及有效预应力的控制方法。 相似文献
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The anchor stress extent of a prestress anchor cable project has a direct relation with the project safety and performance. Prestressed tensioning method is a kind of nondestructive testing method, by which a reverse stretching load is applied on the external exposure section of anchor cable under construction or in service, and then the elongation variation of stress bars is measured to determine the anchor stress. We elaborated the theory and testing mechanism of prestressed tensioning method, and systematically studied key issues during the prestressed tensioning process of anchor cable by using physical model test, including the composition of tension stress-elongation curve, the variation of anchor stress, the compensation of locked anchor stress, and the judgment of anchor stress, and verified the theory feasibility of prestressed tensioning method. A case study on slope anchor cable of one highway project was conducted to further discuss on the test method, operation procedures and judgment of prestressed tensioning method on obtaining anchor stress, and then the test data of three situations were analyzed. The result provides a theoretical basis and technical base for the application of prestressed tensioning method to the evaluation of construction quality and operation conditions of anchor cable project. 相似文献
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Dynamic tests of three bonded and two unbonded full-prestressed concrete beams were carried out.The purpose was to seek the relation between prestressing force and natural frequency.Test results indicate that the frequency of prestressed concrete(PSC)beam increases with the increase in prestressing force approximately.The results are different from the dynamic characteristics of isotropic material beam subjected to compressive axial force which were put forward by Clough et al.The reason is that the beams were considered as isotropic,homogeneous,linear elastic material in the traditional analysis method.However,more accurate results are required in the analysis of frequency of PSC beam.The constitutive mode of PSC member is analyzed based on microstructure of concrete in this paper.The orthotropic linear elastic mode is used to analyze the relation between dynamic frequency and prestressing force of concrete beam,at the same time the equivalent stiffness of prestressed tendon relating to the prestressing force is added to the bending deformation stiffness of the beam.The analytical value agrees well with the test result,indicating that the current analysis method in this paper is feasible to full-prestressed concrete beam. 相似文献
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To obtain the relationship between use of installment tensioning technology and the bearing capacity of prestressed concrete beams, tensile and cyclic loading tests are conducted on five rectangular prestressed concreted specimens. Two types of prestressed tensioning methods are adopted in the tests, one uses installment tensioning technology to tension beams on days 4, 12, and 8, 12, respectively, and the other adopts the conventional method to tension the beam on day 28 only. The age of concrete, number of times tensioned, and the prestress value of early tensioning are considered in tests. Results show that use of installment tensioning technology has no effect on the bending failure pattern of prestressed concrete beams, but it reduces prestress loss and increases crack and yield loads. 相似文献
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根据近期开展的PFRP布受弯构件加固试验和多年的结构试验经验,并结合工程结构设计、施工经验,对PFRP布加固试验张拉、锚固关键问题提出了符合工程实际的解决方法而能用于工程实际。 相似文献
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伸长法测定杨氏模量实验通常采用光杠杆来测量钢丝形变,存在间接测量量较多、调整仪器和测量时间较长等缺点.具体实验数据及其不确定度的分析证明,采用百分表直接测量钢丝的伸长量可以有效克服这些缺点. 相似文献
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由静态拉伸法结合光放大原理,用一次性增(减)砝码反复读取标尺刻度值的测量方案,对逐步增(减)砝码来测量钢丝微小伸长量的测量方法进行改进,通过对镜与标尺距离的控制,在保证微小伸长量测量质量的前提下,确定望远镜可视距离内的最佳镜与尺距离。由实验原理及其不确定度的分析,结合测量数据,计算出钢丝的杨氏模量。用置信概率为95%的不确定度对实验数据进行分析与评定,得到了较为合理的实验结果。 相似文献
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Carbon fiber reinforced polymer(CFRP)bars were prestressed for the structural strengthening of 8 T-shaped rein-forced concrete (RC)beams of a 21-year-old bridge in China.The ultimate bearing capacity of the existing bridge after retrofit was discussed on the basis of concrete structures theory.The flexural strengths of RC beams strengthened with CFRP bars were controlled by the failure of concrete in compression and a prestressing method was applied in the retrofit.The field construction processes of strengthening with CFRP bars-including grouting cracks,cutting groove,grouting epoxy and embedding CFRP bars,surface treating,banding with the U-type CFRP sheets,releasing external prestressed steel tendons-were introduced in detail.In order to evaluate the effectiveness of this strengthening method,field tests using vehicles as live load were applied before and after the retrofit.The test results of deflection and concrete strain of the T-shaped beams with and without strengthening show that the capacity of the repaired bridge,including the bending strength and stiffness,is enhanced.The measurements of crack width also indicate that this strengthening method can enhance the durability of bridges.Therefore,the proposed strengthening technology is feasible and effective. 相似文献
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王传明 《杨凌职业技术学院学报》2008,7(4):47-49
针对韦水倒虹钢筋砼管道受水中推移质撞击、管道底部形成冲槽、受力钢筋磨损、钢筋截面减小、结构安全度降低等特点,提出了在钢筋砼管道底部90°范围内进行粘钢补强加固的技术方案,并论述了粘钢补强加固方案的设计原理及施工工艺。 相似文献