Flexural Behavior of RC Continuous Beams Strengthened by Cementitious Composite Materials

Due to their great strain capacity, high tensile strength, and ability to localize cracks, cementitious composite materials are beneficial for strengthening reinforced concrete (RC) members. This paper illustrates the application of cementitious composite materials in the form of precast thin layers to strengthen a double-spanned, full-scale RC beam. Both positive and negative zones were strengthened by the precast layer embedded into the concrete cover. The precast layers have a dimension of ۲۰ mm in thickness and ۱۵۰ mm in width as that of the substrate beam and were applied by two configurations: plain and reinforced layers. A ductile smooth steel sheet with ۲ mm in thickness and ۱۰۰ mm in width was used inside the reinforced precast layer. The composite action of the precast layer has mutual benefits; the embedded steel sheet localizes the cracks, while the surrounding cementitious composite materials protect the steel sheet from environmental impact. The experimental results showed that the strengthening system has a significant contribution to improve the failure mode and load-carrying capacity. The use of a plain precast layer caused a ۶% increase in the ultimate load and a ۳۳% enhancement in the moment redistribution ratio compared to the control beam (CB). Applying the strengthening system with reinforced precast layer shifted the failure mode from rupture failure in the precast layer to delamination without slippage in the embedded steel sheet and matrix, leading to the full tensile capacity of the precast layer. Besides, the yielded and ultimate loads increased by ۳۴% and ۴۱%, respectively, and maximum deflection increased by ۳۶%. In addition, the beam's ductility increased by ۳۶%, and the moment redistribution ratio was enhanced by ۴۹% compared to the CB. Doi: ۱۰.۲۸۹۹۱/CEJ-۲۰۲۴-۰۱۰-۰۹-۰۵ Full Text: PDF

کلیدواژه ها:

Continuous RC Beams ، Cementitious Composite Materials ، Moment Redistribution ، Precast Layer.