Behaviour of FRP-reinforced concrete beam-column joints

钢筋的腐蚀导致混凝土结构的维护和维修成本很高，特别是在恶劣环境中建造的混凝土结构。最近的研究表明，用无腐蚀纤维增强聚合物（FRP）复合筋加固的单个混凝土构件（梁、板和柱）在单调和循环荷载条件下都表现良好。然而，在这些单独的成员之间的连接（关节）上进行了非常有限的工作，以形成框架结构。节点需要作为相邻柱和梁构件的约束，并在必要时发挥其全部非弹性能力。由于FRP筋在破坏前具有线性弹性，并且在弯曲或承受压应力时显示强度降低，因此在使用FRP筋时，特别是在地震荷载下，需要关注这些节点的延性性能和完整性。本研究项目将重点研究frp钢筋混凝土梁柱节点的性能。研究计划包括实验室调查和分析建模。全尺寸frp钢筋混凝土梁柱节点（内部和外部）将在实验室进行测试。测试参数将包括加载类型（单调或循环），节点核心的约束量（FRP箍筋的杆径和间距），柱轴向载荷，混凝土强度，FRP主筋类型和比例，以及钢筋细节。考虑到FRP与钢筋在力学性能和粘结特性上的本质差异，非线性有限元分析将用于模拟连接板上应力和应变的复杂分布。该模型将被编入计算机代码，并根据实验结果进行校准。然后，计算机代码将用于进行参数化研究，以调查预计会影响此类关节行为的各种因素。试验结果将形成延性和整体梁柱节点的设计方程。这项研究带来了性能更好、耐久性更好、寿命周期成本更低的新结构。

Corrosion of steel reinforcement has led to high maintenance and repair cost for concrete structures especially those built in harsh environments. Recent research indicated that the individual concrete members (beams, slabs, and columns) reinforced with the non-corrodible fibre reinforced polymer (FRP) composite bars behaved well under both monotonic and cyclic loading conditions. However, very limited work was conducted on the connections (joints) of these individual members to form a frame structure. Joints are required to function as restraint to adjoining column and beam members and develop their full inelastic capacity if necessary. Since FRP bars have a linear elastic behaviour till failure and show reduced strengths when bent or subjected to compressive stresses, there are concerns on the ductility performance and the integrity of such joints when FRP bars are use, especially under seismic loads. This research program will focus on investigating the behaviour of FRP-reinforced concrete beam-column joints. The research program consists of laboratory investigation and analytical modelling. Full-scale FRP-reinforced concrete beam-column joints (interior and exterior) will be tested in the laboratory. The test parameters will include the type of loading (monotonic or cyclic), the amount of confinement for the joint core (bar diameter and spacing of FRP stirrups), column axial load, concrete strength, FRP main reinforcement type and ratio, and detailing of reinforcement. Nonlinear finite element analysis will be used to model the complex distribution of stresses and strains at the joint panel in lights of the essential differences in mechanical properties and bond characteristics between FRP and steel bars. This model will be incorporated into a computer code, which will be calibrated against the experimental results. Then, the computer code will be used to perform parametric studies to investigate a wide range of factors that are expected to affect the behaviour of such joints. The test results will be formulated into design equations for ductile and integral beam-column joints. This research leads to new structures with improved performance, better durability and less life-cycle cost.