30m非标预应力钢筋混凝土折线型屋架荷载试验研究

在对金川集团公司三厂区15kt／a海绵钛项目30m非标预应力钢筋混凝土折线型屋架进行荷载试验研究的基础上,较为详细地论述了预应力钢筋混凝土屋架的试验方法。本次试验中将3榀屋架作为一个整体进行测试。对屋架构件几何尺寸、屋架外观质量与缺陷、混凝土抗压强度、挠度、裂缝情况等指标进行了检测,并做了相应的定性分析,为类似的结构试验提供了范例,也给今后的非标屋架设计和非标屋架制作提供了重要依据。     

2lm预应力折线型混凝土屋架在粮库工程的应用

通辽市八仙筒国家粮食储备库扩建工程中6栋粮仓采用21m跨预应力屋架做屋面承重结构，匡架在现场制作，热轧带肋钢筋作预应力筋，采用4根吊索吊装法，安装获得成功。     

预应力混凝土折线型屋架的冬季施工

北方地区有较长的寒冷季节,受工期制约和各种因素的影响,许多工程的混凝土冬季施工是不可避免的。由于缺乏冬季施工的经验,往往会给工程的质量带来不良的影响。本文结合工程实例,通过阐述冬季预应力混凝土屋架的预制、蒸汽养护等施工技术,给在寒冷地区进行冬季施工提供一些借鉴。     

高空散装法在空间网架结构施工中的应用

根据新疆八钢游泳馆网架式屋架的制作、安装的成功经验 ,介绍了网架式屋架的制作要点和技术要求 ,以及高空滑移安装法在网架式屋架安装中的应用。     

某金工车间5吨吊车梁的裂缝分析及加固

江苏冶金机械厂金工车间,建筑面积为3960m~2,有四跨,其中两跨为18m,柱顶标高8.8m,其余两跨为15m,柱顶标高6.8m,柱距为6m,各跨均设有二台5吨中级制吊车,屋面、屋架均采用瓦屋面和三角拱形屋架,并设有6m天窗架和钢筋混凝土檩条,1958年开始建造,1959年建成投产使用。1988年安全大检查时发现该车间屋架、檩条、柱、吊车梁等构件多处产生了裂缝。经     

单层工业厂房抗震设计中的节点问题

本文通过对地震区意志层工业厂房特有的震害现象，分析了屋面板与屋架，屋架与柱、柱间支撑与柱等节点的抗震性能。强调了对加强屋架与柱头的节点，柱头颈埋件及柱间支撑的上下接节点等一些较为关键部位的重点性。     

有粘结预应力混凝土梁施工

包头市东海商厦主体框架梁采用有粘结预应力技术,预应力张拉过程中采用了应力控制、伸长值校核的双控措施.文中介绍了该项技术的施工工艺及曲线有粘结预应力筋理论张拉伸长值的计算.     

33m跨钢管屋架吊装施工

33m跨钢管屋架吊装工程由于准备充分、方案科学、组织工作到位 ,在短时间内吊装成功     

27m跨度厂房屋架的吊装方案

结合现场生产情况,对屋架吊装进行可行性分析研究,经计算后选择了合适的吊装机具,节约了施工成本。     

在公路桥梁施工中预应力技术的应用分析

在目前采用预应力的公路桥梁当中,许多问题仍然作为阻碍存在着,但这并非是对预应力的怀疑,在预应力的应用方面不足,细节起到了很大的作用,本文着重从两点对预应力的应用进行分析,包括预应力桥梁的施工工艺问题,从容易导致裂缝的张拉入手,再到锚具的选择,希望在施工当中可以起到避免问题的作用.     

Deflection Control of Concrete Beams Pretensioned by CFRP Reinforcements

Use of carbon fiber reinforced polymers (CFRP) reinforcement for prestressing concrete structures introduces a promising solution for deterioration of concrete structures due to corrosion of steel reinforcements. Due to the low elastic modulus and limited strain at failure of CFRP reinforcement, partial prestressing could be the most appropriate approach to enhance deformability and reduce the cost in comparison to fully prestressed concrete structures. For members reinforced or prestressed with fiber reinforced polymers reinforcements, serviceability requirements may be the governing criteria for the design; therefore, deflection under service loading conditions should be well defined. This paper introduces simplified methods to calculate the deflection of beams prestressed by CFRP reinforcement under short-term and repeated loading. It also examines the applicability of current approaches available to calculate the deflection. Based on an experimental program undertaken at the University of Manitoba, bond factors are introduced to account for tension stiffening of concrete beams prestressed by CFRP. A procedure to determine the location of the centroidal axis of cracked prestressed sections is also proposed. The proposed methods for deflection calculation are calibrated using the results obtained from different experimental programs. Design guidelines are proposed to predict the deflection of beams partially prestressed by CFRP reinforcement.     

乌海市地税局工程预应力梁施工技术

文章介绍乌海市地税局大楼副楼预应力梁后张法的预应力筋制作,孔道的安装,预应力张拉,孔道灌浆等施工技术,以及施工方法和注意事项进行了阐述。     

多功能新材质屋面板设计施工

通过设计一种具有透明、保温、防水、防腐等多功能,且自重仅为原预应力砼屋面板10%的钢框玻璃钢罩屋面板,解决老厂屋面改造存在的生产与施工难题.     

破碎软岩中长锚索支护参数设计及其应用

云南某铜矿地质条件复杂,矿体和围岩均较破碎且含泥量高,需对其进行大量加固支护。综合分析后,考虑采用长锚索加固技术,对4#矿体进行围岩预支护、分层整体锚固及顶板长锚索加固。根据矿岩性质及采场结构,进行了锚索支护参数设计。试验结果表明,长锚索加固技术对于厚大破碎矿体适用性强,能有效防止围岩冒落、顶板垮塌及维护巷道完整性。矿石回收率比现用采矿方法提高近20%,矿石贫化率降低8%,经济效益显著。     

Improved Longitudinal Joint Details in Decked Bulb Tees for Accelerated Bridge Construction: Fatigue Evaluation

This companion paper focuses on an investigation of improved continuous longitudinal joint details for decked precast prestressed concrete girder bridge systems. Precast concrete girders with an integral deck, which are cast and prestressed with the girder, provide benefits of rapid construction along with improved structural performance and durability. Despite these advantages, the use of this type of construction has been limited to isolated regions of the United States. One of the issues limiting more widespread use is the perceived problem with durability of longitudinal joints used to connect adjacent girders. Four full-scale slabs connected by No. 16 (#5) headed reinforcement detail using a 152 mm (6 in.) lap length were fabricated and tested. An analytical parametric study was conducted to provide a database of maximum forces in the longitudinal joint. These maximum forces are then used to determine the loading demand necessary in the slab testing due to the service live load. Static and fatigue tests under four-point pure-flexural loading, as well as three-point flexural-shear loading, were conducted. Test results were evaluated based on flexural capacity, curvature behavior, cracking, deflection, and steel strain. Based on these test results, the improved longitudinal joint detail is a viable connection system that transfers the forces between the adjacent decked bulb tee girders.     

盘区下向充填分层道稳定性数值模拟

龙首矿采用下向水平分层六角形进路充填采矿法,分层道是关键通道,其稳定性至关重要。应用FLAC3D软件建立了分层道及六角形进路数值模型,应用强度等效原则确定了分层道底部配筋充填体的力学参数。分别研究了分层道假顶为素充填体和配筋充填体情况下的稳定性。结果表明,分层道开挖暴露的大面积矩形薄板,最大挠曲在中部位置,破坏方式从中部开始拉断破坏,应在开采过程中加强对顶板的支护及对中部位置的监测。此外,分层道假顶为素充填体时不利于矿山的安全生产,尤其在进路与分层道交叉巷道处,应加密配筋密度,防止出现冒落及掉块现象。     

Effect of Partial Unbonding on Prestressed Near-Surface-Mounted CFRP-Strengthened Concrete T-Beams

The flexural behavior of RC T-beams strengthened with prestressed near-surface-mounted (NSM) carbon fiber-reinforced-polymer (CFRP) reinforcement was investigated. The specific objective was to study the effect of partial unbonding of the CFRP reinforcement on the beam flexural behavior to increase the deformability. A total of eight RC T-beams were tested under four-point monotonic loading. The main variables were the level of prestressing force in the CFRP bars and the unbonded length at the midspan of the beam. The test results showed that all of the prestressed strengthened beams effectively improved the ultimate load-carrying capacity and the serviceability performance compared to the unstrengthened beam. The partially bonded prestressed beams exhibited an enhancement of the deformability compared to the fully bonded beams while minimizing the reduction of the load-carrying capacity. Partial unbonding was more effective to improve the deformability at higher levels of prestressing force. The general behavior of the partially bonded beams was reasonably well predicted by an analytical model developed previously by the writers.     

Posttensioned Anchorage Zone Enhancement with Fiber-Reinforced Concrete

The secondary spiral and skin reinforcement in the anchorage zone of prestressed posttensioned girders causes congestion and poses difficulty in the placement of concrete. It is also labor intensive to produce and place secondary anchorage reinforcement. The objective of this study was to determine the feasibility of reducing the secondary reinforcement with steel fibers for posttensioned anchor zones. The AASHTO Special Anchorage Device Acceptance Test was performed in this study. Variations of spiral and skin reinforcement, with concrete strengths ranging from 37.9?MPa (5,500?psi)?to?52?MPa (7,500?psi), were utilized to investigate the performance of the two types of steel fibers with various amounts. The experimental results indicated that 1% hooked-end steel fibers could eliminate all secondary reinforcement for a minimum concrete strength of 40.7?MPa (5,900?psi). Lower volumes of steel fibers may also be used to reduce secondary reinforcements.     

概念设计在厂房加固改造工程中的应用

介绍了工业厂房加固改造和对厂房结构进行临时加固作为设备吊装平台的两个实例,实践证明,应用结构概念设计的方法可以提高结构设计效率和解决问题的能力。