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先简支后连续混凝土梁负弯矩区UHPC “T形”湿接缝试验研究
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Experimental Study on UHPC “T-shaped” Wet Joints in the Negative Moment Zone of Continuous Concrete Beams after Simple Support
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    摘要:

    为了提高普通混凝土连续梁负弯矩区湿接缝的抗裂性能,简化施工工艺,提出了混凝土梁桥负弯矩区UHPC新型湿接缝方案. 以某跨径为30 m的普通混凝土连续梁桥为背景,根据法国UHPC结构设计规程和《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG 3362—2018)对该桥进行正常使用极限状态下的配筋设计,并参照配筋设计结果对UHPC新型湿接缝构造进行1 ∶ 2缩尺模型试验研究. 试验结果表明:取消负弯矩区预应力束、取消焊接的负弯矩区UHPC新型湿接缝方案的抗裂性能和承载能力均满足工程要求,且试验值与数值模拟值拟合良好;UHPC的引入能有效限制普通混凝土的裂缝宽度,显著提高普通混凝土截面的刚度,改善混凝土连续梁跨中区的内力及竖向挠度的重分布现象. 与不考虑负弯矩预应力束的传统湿接缝构造相比,UHPC新型接缝构造能降低混凝土连续梁内力及跨中竖向挠度的重分布系数至其30%~50%. 参数分析表明:对于负弯矩区采用UHPC新型湿接缝构造的混凝土连续梁桥,UHPC沿纵桥向的长度宜取0.27倍计算跨径,负弯矩区纵向受拉主筋直径可统一为20 mm,UHPC层的厚度取60 mm即可.

    Abstract:

    In order to improve the crack resistance of wet joints in the negative bending moment area of ordinary concrete continuous beams and simplify the construction process,a new type of UHPC wet joint scheme for the negative bending moment area of concrete beam bridges was proposed. Taking a common concrete continuous beam bridge with a span of 30m as the background,according to the French UHPC structural design regulations and Chinese Specification for Design of Highway Reinforced Concrete and Prestressed Concrete bridge and Culverts(JTG 3362—2018),the reinforcement design of the bridge under normal service limit state is carried out. Based on the results of reinforcement design,the 1 ∶ 2 scale model test of UHPC new wet joint structure was carried out. The test results show that the crack resistance and load-bearing capacity of the UHPC new wet joint scheme without reinforcement welding and prestressed strands in the negative bending moment area are all in line with the engineering requirements. The test values are well fitted with the numerical simulation values. The introduction of UHPC can effectively limit the crack width of normal concrete(NC),significantly increase the rigidity of NC section,and reduce the redistribution of internal force and vertical deflection of the continuous concrete beam in the mid-span. Compared with the traditional wet joint structure without negative bending moment prestressed tendon,the new UHPC joint structure can reduce the redistribution coefficient of the internal force and vertical deflection of the continuous concrete beam to about 30%~50%. The parameter analysis shows that: for the concrete continuous beam bridge with UHPC new wet joint structure in the negative bending moment area,the length of UHPC along the longitudinal direction of the bridge should be taken to be 0.27 times the calculated span. The diameter of the longitudinal tensile main bars in the negative bending moment area can be unified to 20 mm,and the thickness of the UHPC layer can be 60 mm.

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邵旭东?覮,孔小璇,邱明红,陈玉宝.先简支后连续混凝土梁负弯矩区UHPC “T形”湿接缝试验研究[J].湖南大学学报:自然科学版,2021,48(3):1~13

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  • 在线发布日期: 2021-03-23
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