Pretest analysis of shake table response of a two-span steel girder bridge incorporating accelerated bridge construction connections

This paper presents pretest analysis of a shake table test model of a 0.35-scale, two-span, steel plate girder bridge. The objective of pretest analysis was to obtain an insight on the seismic response of the bridge model during the shake table tests. The bridge included seat type abutments, full-depth precast deck panels, and a two-column bent in which columns were pinned to the footing and integral with superstructure. Six accelerated bridge construction connections were incorporated in the bridge model. An analytical model was developed in OpenSees and was subjected to ten input bi-directional earthquake motions including near-fault and far-field records. The overall seismic response of the bridge was satisfactory for all the earthquake records at 100%, 150%, and 200% design level. All connections and capacity-protected components remained elastic, and the average ductility capacity surpassed the ductility demand even at 200% design level. Using experimental fragility curves developed for RC bridge columns, it was predicted that there was a probability of 45% that columns would undergo the imminent failure in the last run and a probability of 30% for their failure.     

超高性能轻型组合桥面沥青磨耗层界面抗剪性能研究

为研究沥青磨耗层-UHPC层间抗剪性能,基于剪切破坏能量分析原理,提出剪切断裂能计算方法;针对新、旧两种界面状况,开展沥青磨耗层-UHPC层间斜剪试验,得到荷载-界面位移全过程曲线;通过模拟不利环境复合试件老化过程,研究新、旧界面抗剪性能劣化规律;探究重铺磨耗层黏结剂用量对于修复效果的影响。研究表明:剪切断裂能综合反映层间剪切强度和剪切推移量的大小,能够更加全面地表征层间抗剪特性;荷载-界面位移全过程曲线呈现出四个阶段;在水损害、高温湿热、氯盐侵蚀等不利自然环境下,复合试件层间抗剪性能劣化规律具有相似性,但老化程度存在差异,环境影响排序为:水损坏>氯盐高湿>湿热环境;修复过程中黏结剂的用量对于修复效果影响显著,建议采用0.7kg/m²的黏结剂用量;旧界面试件的剪切强度、剪切断裂能均小于新界面试件,两者差值随着循环次数增加而逐渐增大,修复后层间耐老化性能有所降低。     

Design and construction of UHPC-filled duct connections for precast bridge columns in high seismic zones

One of the column connection types that has been recently emphasised for accelerated bridge construction (ABC) in high seismic zones is grout-filled duct connections. Experimental results have shown that the seismic behaviour of reinforced concrete columns connected to precast cap beams using this connection type is emulative of conventional columns. However, an alternative ABC connection is required to connect precast columns to shallow cap beams and footings due to insufficient anchorage length in those elements. Ultra-high-performance concrete (UHPC) was proposed in this study to be used instead of conventional grout in the connection to reduce the anchorage length. First, fourteen large-scale pullout tests were performed to investigate the bond strength of UHPC-filled duct connections. The test results showed that the incorporation of UHPC instead of normal grout as duct filler can reduce the bar embedment length by 50% or more. Second, design equations were developed based on the pullout test data to compute the bar development length in these connections. Subsequently, two half-scale precast bridge columns utilising this connection type at the column base were tested to verify the design equations. Full column plastic moment was developed in both specimens under cyclic loading with no UHPC-filled duct connection failure such as bar pullout even under 12% drift ratio cycles. Finally, a guideline was proposed based on the pullout and column test data for the design and construction of the UHPC-filled duct connections to facilitate field deployment.     

20mT异型组合梁桥加固设计与施工

介绍了某T异型组合梁桥采用体外应力体系进行加固的设计要点,通过对加固前后的各截面进行计算比较,证明加固方案可行,并着重阐述了施工技术,为采用类似技术进行桥梁加固的设计和施工提供了宝贵经验。     

钢 超薄UHPC轻型组合桥面短钢筋连接件#br# 抗剪性能研究

为解决钢-超薄UHPC轻型组合桥面板由于UHPC层过薄而难以采用常规剪力连接件的问题,提出一种新型剪力连接件 短钢筋连接件。通过静力推出试验以及疲劳推出试验对短钢筋连接件的抗剪性能进行初步研究。静力推出试验结果表明：①该试验存在焊缝剪断和UHPC局部破坏(短钢筋拔出)两种破坏模式;②短钢筋连接件承载力随着焊缝长度增加而提高;③短钢筋连接件抗剪承载力高于栓钉,略低于钢筋网焊接件。疲劳推出试验结果表明：80MPa剪应力幅下,3个试件疲劳寿命分别为194.2、271.0、195.8万次,去掉最大值,剩余两者平均疲劳寿命为195万次,略低于规范相应的200万次。通过Miner-Palmgren线性累积损伤理论对不同应力幅下的疲劳次数转化,可得200万次疲劳下的剪应力幅为79.6MPa。仿真结果表明：在纵横向间距200mm×200mm布置方式下,两类疲劳细节(连接件位置与钢顶板位置)均能够满足抗剪疲劳设计要求。文章研究成果可为今后实桥应用提供理论依据。     

钢混连续结合梁施工技术

结合某工程钢混连续结合梁施工实例,介绍了钢混连续结合梁在场地较平坦时钢梁吊装架设及混凝土面板一次现浇的施工方法,通过使用此法,缩短了工期,降低了工程造价,其经济和社会效益显著。     

Field validation of UHPC layer in negative moment region of steel-concrete composite continuous girder bridge

Improving the cracking resistance of steel-normal concrete (NC) composite beams in the negative moment region is one of the main tasks in designing continuous composite beam (CCB) bridges due to the low tensile strength of the NC deck at pier supports. This study proposed an innovative structural configuration for the negative bending moment region in a steel-concrete CCB bridge with the aid of ultrahigh performance concrete (UHPC) layer. In order to investigate the feasibility and effectiveness of this new UHPC jointed structure in the negative bending moment region, field load testing was conducted on a newly built full-scale bridge. The newly designed structural configuration was described in detail regarding the structural characteristics (cracking resistance, economy, durability, and constructability). In the field investigation, strains on the surface of the concrete bridge deck, rebar, and steel beam in the negative bending moment region, as well as mid-span deflection, were measured under different load cases. Also, a finite element model for the four-span superstructure of the full-scale bridge was established and validated by the field test results. The simulated results in terms of strains and mid-span deflection showed moderate consistency with the test results. This field test and the finite element model results demonstrated that the new configuration with the UHPC layer provided an effective alternative for the negative bending moment region of the composite beam.     

UEA补偿收缩混凝土在桥梁拼接施工中的应用

着重介绍了UEA补偿收缩混凝土在桥梁拼接中的应用,具体阐述了拼接部位裂缝控制措施,从而解决了桥梁拼接施工过程中产生收缩裂缝的问题,以提高桥梁拼接部位混凝土的施工质量。     

桥梁混凝土裂缝的施工控制技术

本文探讨了桥梁混凝土的裂缝施工控制方法,并结合义乌宗泽大桥混凝土V型墩的实际施工过程,分析了V型墩斜腿根部产生裂缝的原因,提出了义乌宗泽大桥的V型墩施工控制方案。     

预应力混凝土桥梁施工质量控制要点

总结了预应力混凝土结构刚度强、抗裂度强,增强建筑结构的使用性能和耐久性,以及节省钢筋混凝土用量等诸多优点,结合实际施工,就预应力混凝土桥梁施工质量控制要点进行了详细的分析和阐述,以供相关人员进行参考和借鉴。     

含小型粗骨料UHPC板抗弯性能研究

研制新型的含小型粗骨料UHPC板,提升传统大跨径组合梁斜拉桥普通混凝土桥面板的抗弯性能。通过对含小型粗骨料UHPC进行基本材料性能研究,以及对含小型粗骨料UHPC板试件进行抗弯试验,材性试验探究含小型粗骨料UHPC材料的本构关系、弹性模量和终凝后的干燥自收缩等,发现在UHPC中添加小型粗骨料后,UHPC在抗压性能方面得到提高,减小终凝后的干燥自收缩,但会降低一定的抗弯拉强度和韧性;含小型粗骨料UHPC板试件的抗弯试验探究了试件的荷载 挠度关系与弯矩 最大裂缝宽度关系。发现UHPC板试件具有较高的开裂强度,结构破坏呈现出多裂缝发展。抗弯试验、有限元分析和承载力公式计算结果表明：含小型粗骨料UHPC板具有较好的抗弯、抗裂性能,但计算承载能力时应充分考虑添加小型粗骨料后对结构拉伸性能降低的影响。     

古浪河大桥钢梁现浇混凝土结合梁拖拉施工

结合古浪河大桥钢梁工程实例，就其钢梁总体施工方案的布置进行了介绍，从钢梁拼装、上下滑道布置、拖拉架设施工等方面，阐述了具体的施工工艺措施，并总结了结合梁拖拉的施工体会。     

桥梁施工中混凝土养护技术探讨

从桥梁施工中混凝土养护原理着手,通过分析研究提出了桥梁混凝土的养护方法及混凝土的养护质量检查等,进而防止桥梁病害的发生,确保桥梁结构的施工质量和使用安全。     

南宁大桥主桥上部混凝土结构施工总结

以南宁大桥工程为例,结合该桥梁主桥上部混凝土结构概况,对肋间平台施工、劲性骨架设计、预应力施工、混凝土施工等关键工序的施工要点进行了分析研究,并针对混凝土拱肋施工中存在的问题提出了解决措施,以供参考。     

后张法预应力混凝土桥梁施工技术应用

以晋城市太行一号国家风景公路桥梁工程为例,探讨预应力后张力混凝土桥梁项目施工技术的若干要点,如支架的具体安装、模版的实际搭设、孔道的谨慎安装、对钢筋的绑扎等,就预应力后张法混凝土路桥工程的施工中的实际应用展开解析。     

桥梁建筑中伸缩缝设计研究

深入阐述了当前桥梁建筑中伸缩缝的主要形式,探讨了影响桥梁建筑中伸缩缝的因素,重点从设计方面探究了桥梁建筑中伸缩缝的设计方法及其理论依据,并用工程实例加以说明,以指导实践。     

桥梁混凝土防撞护栏精细化施工技术探讨

结合繁大高速公路桥梁施工实践,针对桥梁混凝土防撞护栏精细化施工技术进行了探讨,分别阐述了钢筋绑扎,模板拼装,混凝土拌和及浇筑等关键工序操作要点和施工要求,从而得出桥梁混凝土护栏精细化施工流程。     

钢-UHPC轻型组合桥面结构试验及裂缝宽度计算研究

为研究钢-UHPC轻型组合桥面结构的裂缝特征,并评估现有规范公式对钢-UHPC轻型组合桥面结构裂缝宽度计算的适用性,综合考虑配筋率、保护层厚度、UHPC层厚度和栓钉间距4个因素,对40个钢-UHPC组合板进行正交试验。试验结果表明：未配筋钢-UHPC组合构件裂缝数量较少,且开裂后裂缝发展较快,密集配筋钢-UHPC组合构件裂缝细而密,在裂缝宽度为0.15mm之前,荷载-最大裂缝宽度曲线大致呈直线,钢筋屈服后,裂缝发展较快,当裂缝宽度达到0.2mm以后,裂缝数量基本趋于不变;配筋率和保护层厚度对开裂应力和平均裂缝间距的影响较大,UHPC层厚度对其影响不大。根据现有规范公式计算钢-UHPC组合结构裂缝宽度过于保守,文中根据钢-UHPC组合桥面结构的特点和裂缝扩展特征,提出钢筋应力的计算方法,计算结果和试验实测结果吻合较好;在现有规范公式的基础上,对平均裂缝间距计算公式和钢筋应变不均匀系数计算公式进行了修正,给出钢-UHPC轻型组合结构最大裂缝宽度建议公式,建议公式的计算值和试验值吻合较好。     

混凝土桥梁冬季施工方案及防裂措施

分析了混凝土受冻后强度所受到的影响,论述了蓄热法、暖棚法、低温早强混凝土法、冷混凝土法、蒸汽加热法和电热法等混凝土冬季施工方法,对施工中防止产生裂纹的技术措施进行了探讨。     

水泥混凝土桥面铺装施工质量控制

结合桥面铺装的施工实践,从铰缝混凝土施工和桥面铺装混凝土施工两方面介绍了水泥混凝土桥面铺装施工中的质量控制要点,以完善桥面铺装施工工艺,保证桥面混凝土铺装层具有设计强度、整体性及抗渗抗裂抗冲击性。