预应力UHPC加固RC梁抗弯性能试验研究

Experimental Study on Flexural Behavior of RC Beams Strengthened with Prestressed Ultra-high Performance Concrete

提出了预应力UHPC加固技术,以期实现损伤RC结构更加高效耐久的加固防护.为研究该加固技术对RC梁抗弯性能的影响和作用,对加固层分别为常规配筋UHPC层、预应力UHPC层的2根损伤RC加固梁(Reinforced-UHPC Strengthened Beam,RUB和Prestressed UHPC Strengthened Beam,PUB)以及1根未加固RC对比梁(Reinforced Concrete Beam,RCB)进行了正截面抗弯试验,试验结果显示:试验梁均表现为传统的弯曲破坏,损伤RC梁加固后抗弯性能较未加固梁有显著提升;其中预应力UHPC层加固效率明显高于常规配筋UHPC层,预应力UHPC加固层改善了结构应力状态,进一步抑制了裂缝的形成与开展;此外,预应力UHPC加固层更为出色的拉伸性能使得RC梁的抗弯刚度和极限承载力得到更为明显的提升.PUB加固梁在开裂荷载以及抗弯极限承载能力上较RUB加固梁分别提升了89.2%、36.9%.同时提出了预应力UHPC加固梁极限承载力计算公式,计算结果与试验结果吻合良好.

Prestressed UHPC strengthening technology was proposed to achieve a more efficient and durable strengthening for damaged RC structures.In order to investigate the effect of prestressed UHPC strengthening tech⁃nology on flexural behavior of RC beams,normal section bending tests were carried out on two damaged RC strength⁃ened beams(Reinforced-UHPC Strengthened Beam,RUB and Prestressed-UHPC Strengthened Beam,PUB)and one unstrengthened contrast RC beam(Reinforced Concrete Beam,RCB).Among strengthened beams,RUB was strengthened by the reinforced UHPC layer,and PUB was strengthened by the prestressed UHPC layer.The experi⁃mental results showed that all test beams showed conventional bending failure,and the flexural behavior of RC beams was significantly improved after being strengthened.The flexural strengthening efficiency of the prestressed UHPC layer was higher than that of the reinforced UHPC layer.The prestressed UHPC layer improved the stress state of the structure and further inhibited the formation and development of cracks.In addition,the better tensile performance of the prestressed UHPC layer made the flexural stiffness and ultimate bearing capacity of RC beams further improved.Compared with RUB,the cracking load and ultimate bearing capacity of PUB were increased by 89.2%and 36.9%,respectively.Also,a calculation formula of ultimate bearing capacity of prestressed UHPC strengthened beam was proposed,and the calculation results were in good agreement with the experimental results.