Assembly and Connection of Precast/Prestressed Concrete Members - Validation and Optimization of two Accelerated Construction Methods

预制/预应力结构混凝土组件的使用与现浇相比具有几个优势，包括施工方便和速度，实现更高效和复杂的形状，长跨度，高水平的防火性，增强的耐久性和可持续性。然而，至关重要的是，这些单独的结构部件组装和连接形成一个整体结构，可以在其使用寿命期间抵抗不同类型的负载组合。本研究计划的重点是两种常见的预制结构元件的组装和连接。第一种是相邻箱梁的拼装，通过横向后张拉（TPT）相互对接形成桥面。目前的做法是通过离散的横向隔板来应用TPT，这并不能防止梁之间的开裂和差异挠度，反而会中断公用线路，导致额外的成本，特别是在倾斜的桥梁中。本研究的第一个目的是探讨箱梁上翼缘提供均匀分布TPT的可行性，并评估梁间的开裂、挠度和荷载分担能力。要研究的第二种连接类型是建筑物中空心板与支撑元件之间的连接，它确保了结构的完整性。这种连接旨在抵抗平面内水平载荷。目前的做法是使用钢筋作为这种连接的锚。然而，没有设计指南可用于预测这种连接的容量或其失效模式。提出的研究的第二个目标是评估，表征和开发模型来预测这种连接的强度。将进行全面和大规模的实验室测试和分析调查，以评估组装预制构件的性能，以评估与它们在桥梁和建筑物中的应用有关的具体问题。这将带来安全的新结构，具有更好的性能，更好的耐久性，更低的建设成本，并减少基础设施所有者（如交通部，市政当局和公共工程部）的维护成本。

The use of precast/prestressed structural concrete components offers several advantages over their cast-in-place counterparts including ease and speed of construction, achieving more efficient and complex shapes, long spans, high levels of fire resistance, enhanced durability and sustainability. However, it is essential that these individual structural components be assembled and connected to form an integral structure that can resist different types of load combinations during its service life. This research proposal focuses on the assembly and connection of two common types of precast structural elements. The first type is the assembly of adjacent bridge box girders that are butted against each other to form the bridge deck through transverse post-tensioning (TPT). The current practice is to apply the TPT through discrete transverse diaphragms, which does not prevent the cracking and differential deflection between girders, but rather interrupts utility lines and results in additional costs particularly in skewed bridges. The first objective of this research is to investigate the feasibility of providing uniformly distributed TPT through the top flange of box girders and evaluate cracking, deflection and load sharing capacity between girders. The second type of connection to be studied is the one between hollowcore slabs and supporting elements in buildings, which ensures the integrity of the structure. This connection is intended to resist horizontal in-plane loads. The current practice is to use reinforcing steel bars as anchors for such connections. However, no design guidelines are available to predict the capacity of such a connection or its mode of failure. The second objective of the proposed research is to evaluate, characterize and develop models to predict the strength of such connections. Full- and large-scale laboratory testing and analytical investigations will be performed to assess the performance of assembled precast elements to assess specific problems related to their application in bridges and buildings. This will lead to safe and new structures with improved performance, better durability, less construction cost and cutting the maintenance cost for infrastructure owners such as the Ministries of Transportation, Municipalities and Public Works.