玄武岩纤维复合筋增强自密实纤维混凝土桥面板力学性能及计算理论研究

It was found in a construction project that the concrete bridge deck components constructed by the combination of the basalt fibre reinforced polymer reinforcing bars (BFRP bar) and self-compacting fibre reinforced concrete (SCFRC) was highly durable and low energy. However, the accurate prediction for this structural element has not been developed fully, which limited the further application of this deck slab. Based the study of the behaviour in the BFRP reinforced SCFRC deck slabs in a real bridge, the structural behaviour, loading-carrying capacity, failure mode and the corresponding theoretical methods of BFRP reinforced SCFRC deck slabs will be studied in this research project. In this study, the effect of compressive membrane action (CMA) will be investigated significantly. This research project will be carried out with the combination of theoretical analysis, experimental tests and finite element analysis. Several research works will be conducted as follow: (1) The serviceability and ultimate behaviour of deck slabs will be discussed and presented and the influence degree of some important parameters will be investigated; (2) Based on the results from the experimental tests and finite element analysis, the prediction methods of crack widths and deflections of deck slabs will be modified; (3) The prediction methods of loading-carrying capacities will be proposed by the investigation of the contribution of the structural parameters to ultimate strengths and failure mechanism; (4) In the study of design recommendation for this deck slab, the limit values of some structural parameters will be determined. This research achievement will be beneficial to develop the highly durable and low carbon foot-print concrete deck slabs, which have excellent serviceability and loading-carrying capacity. Therefore, the results from this study can be applied in the construction of sustainable and "green" bridge structures significantly.

已开展工程应用发现，将玄武岩纤维复合筋（简称BFRP筋）与高比例高炉矿渣自密实纤维混凝土相结合建立桥面板具有高耐久性和低能耗的特点，但缺少合理准确的计算理论制约其进一步应用。本研究基于同类型桥面工程应用成果，围绕BFRP筋增强自密纤维实混凝土桥面板工作机理、承载能力、破坏模式及计算理论等核心问题，重点分析压缩薄膜效应作用，将理论分析、结构试验和仿真模拟有机结合、相互推进，具体开展以下研究：1）研究该桥面结构正常使用和极限荷载作用下工作性能，分析各类重要结构参数影响规律；2）基于试验和有限元计算结果，修正该桥面板裂缝和挠度计算方法；3）阐明各个因素对结构承载能力的贡献和破坏机理的影响，建立各类强度预测模型；4）设计方法研究，明确各类结构参数取值范围。本项目研究成果将能在保证桥面结构良好工作性能的基础上，提高结构耐久性能和降低碳排放，对建立可持续性和“绿色”桥梁结构具有显著科学意义。

为建造具有高耐久性和低能耗的“绿色”混凝土桥面结构，本项目提出了将纤维复合材料筋材（简称FRP筋）与高掺量工业副产品的自密实混凝土相结合建立桥面板构件。项目整体围绕FRP筋纤维自密实混凝土桥面板工程机理、承载能力、破坏模式及计算理论等核心问题，将理论分析、结构试验和仿真模拟有机结合、相互推进，重点考虑桥面板内压缩薄膜效应的影响，阐明了新型桥面结构多种力学性能，建立了准确的理论分析方法及设计指标，并开展实际工程应用验证理论体系可行性。项目主要完成工作总结如下：（1）建立了高粉煤掺量（超过50%水泥代替率）自密实混凝土制备工艺，阐明了粉煤灰代替率、水胶比、胶骨比对混凝土材料性能和力学性能的影响；建立了高纤维体积率自密实混凝土制备工艺；（2）开展FRP筋-自密实混凝土粘结滑移及拉伸刚化性能研究，揭示两者协同工作机理及失效过程，提出了粘结滑移及拉伸刚化本构模型，建立了准确的粘结强度和锚固长度计算方法；（3）通过抗弯性能研究揭示了桥面结构正常使用性能，验证了现行设计方法的准确性，建立了基于裂缝宽度的设计指标，提出可行的裂缝间距及裂缝宽度预测方法；（4）考虑压缩薄膜效应影响，揭示了FRP筋自密实混凝泥土桥面板极限荷载作用下工作机理，建立了准确的单向抗剪和抗冲切承载能力计算方法；（5）工程应用结果表明，压缩薄膜效应显著影响FRP筋混凝土桥面结构车载作用下工作性能，侧向约束作用下FRP筋配筋率及配筋材料变化并不会显著影响桥面力学性能；（6）提出了基于压电陶瓷主动传感技术的自密实混凝土早期水化反应、FRP筋-自密实混凝土粘结滑移性能，FRP筋自密实混凝土正常使用性能刚度退化及损伤演化的准确监测技术。研究成果表明：本项目建立的FRP筋自密实混凝土桥面结构及设计方法，将能在保证桥面结构良好工作性能的基础上，提高结构耐久性能和降低碳排放，对我国建立可持续性和“绿色”桥梁结构具有重要科学意义。