单向预应力UHPC连续箱梁桥面体系优化设计研究

Research on optimal design of deck system in longitudinal prestressed UHPC continuous box girder bridge

为方便布置体内预应力束和进一步改善桥面板受力状态,对大跨单向预应力UHPC(Ultra-high Performance Concrete)连续箱梁桥的桥面体系进行优化设计,提出新型正交异性UHPC矮肋板桥面体系方案。以广东省某桥为工程背景,进行了基于正交异性UHPC矮肋板桥面体系方案的UHPC箱梁结构试设计并开展相关的试验研究。结果表明:(1)与矩形桥面板方案相比,优化的正交异性UHPC箱梁矮肋板桥面体系自重可减少17.0%,并可在矮肋板纵肋处方便地布置体内束;与华夫桥面板方案相比,可在不明显增加桥面体系自重的前提下,大幅减小桥面板的纵向应力,降幅可达46.8%;(2)基于正交异性UHPC矮肋板桥面体系的UHPC箱梁方案试设计整体计算满足受力要求,桥面体系计算中标准组合作用下桥面板最大纵向拉应力2.66MPa,横隔板最大横向应力6.09MPa;(3)试验及计算结果表明,矮肋板试件初裂名义应力8.84MPa,抗裂设计名义应力限值10.70MPa,UHPC箱梁横隔板上弦板底面横向应力达到8.43MPa时仍处于线弹性受力阶段,表明试设计方案能满足设计要求。

In order to conveniently arrange the internal prestressing tendon and further improve the performance of deck, the deck system for large-span longitudinal prestressed ultra-high performance concrete （UHPC） continuous box girder bridge was optimized in design, and the novel bridge deck with orthotropic and anisotropic UHPC short-ribbed panel were proposed. With a bridge in Guangdong province taken as an example, the UHPC box girder structure based on orthotropic and anisotropic UHPC short-ribbed deck （OUSRD） was designed and the corresponding experiments were conducted. The results show that： ① compared with the rectangular decks, the self-weight of the deck system with OUSRD can be reduced by 17.0%, and the internal prestressing tendon can be conveniently arranged at the ribs, and compared with the waffle deck panels, the longitudinal stress in the deck panels for the novel desk system can be significantly reduced up to 46.8%, under the premise that the self-weight of the OUSRD is not obviously greater than that of waffle deck panels. ② The entire calculation of the trail design of UHPC box girder with OUSRD meets the requirement of bearing capacity. In the calculation of bridge deck system with characteristic combination of loads, the maximum longitudinal stress in bridge deck and the maximum transverse stress in diaphragm are 2. 66MPa and 6.09MPa, respectively. ③ The tests results reveal that the initial crack nominal stress of the short-ribbed specimen is 8.84MPa, and the limit of nominal stress in the design of crack resistance is 10.70MPa. When the transverse stress at the bottom of upper plate of the diaphragm of UHPC box girder is 8.43MPa, the diaphragm is still in the stage of linear elasticity, indicating that the trail design scheme of UHPC box girder with OUSRD may meet the design requirements.