采用同源材料夹片锚具的玄武岩纤维复材筋体外预应力加固混凝土梁受弯性能研究

FLEXURAL BEHAVIOR OF RC BEAMS PRESTRESSED WITH EXTERNAL BASALT FIBER-REINFORCED POLYMER TENDONS USING A COMPOSITE-WEDGE ANCHORAGE

绿色环保的玄武岩纤维增强复合材料(BFRP)具有高强度和优良的蠕变性能,有望作为预应力材料用于工程结构加固。本文首先针对体外预应力应用中的两大关键技术问题,即锚固和转向问题,提出一种可减小BFRP筋锚固端应力集中的组装式同源材料夹片锚具,同时基于有限元分析,优化了体外预应力BFRP筋的转向角度与转向半径。开展了2组混凝土梁的受弯试验,其中一组为体外预应力BFRP筋加固混凝土梁,另一组为普通混凝土梁。主要研究了结构承载力、延性、裂缝、预应力变化等力学性能。结果表明,所开发的同源材料夹片锚具能够有效、可靠地传递预应力,体外预应力BFRP筋加固后的混凝土梁的开裂荷载、屈服荷载和极限荷载相比未加固梁提升了500%、142%和138%,且具有一定的延性。

Eco-friendly basalt fiber-reinforced polymer(BFRP)is prospective in the structural strengthening as a type of prestressing material,due to its high strength and creep rupture stress.Firstly,focusing on two main technical problems,i.e.anchorage and deviation,an assembling composite-wedge anchorage,which is capable of decreasing the stress concentration of BFRP tendon,is proposed.Additionally,deviation angle and radius are optimized using finite element analysis(FEA).Then,flexural tests on one non-prestressed RC beam and one RC beam prestressed by external BFRP tendon are conducted,and the parameters such as capacity,ductility,crack,stress in prestressing tendons,are discussed and analyzed.The results validate the effectiveness and reliability of the developed composite-wedge anchorage in transferring prestress.The beam prestressed by external BFRP tendon exhibits increases by500%,142%and 138%in its cracking load,yielding load and ultimate load respectively,compared with the unstrengthened beam,and possesses a considerable ductility.