تحسين قدرة الانحناء للعتبات الخرسانية المسلحة المعززة بالواح الكاربون مقدم لكلية الهندسة جامعة كربلاء في استيفاء جزئي لمتطلبات درجة ماجستير العلوم في الهندسة المدنية

Rp: Enhancement of Flexural Capacity of RC Beams Strengthened by CFRP Sheets pdf.

Carbon Fiber Reinforced Polymer (CFRP) sheet are used to improve the properties of concrete in structural components such as buildings and bridges. This composite technique is commonly considered wherever high strength-to-weight ratio and stiffness are required. However, one of the significant issues of this system is the delamination problem. At a certain load level, the CFRP sheets start delamination from the concrete substrate, which results in premature failure. As a result, this experimental research aims to control the delamination by using Poly Vinyl Alcohol (PVA) and Steel Fiber (SFRC) with different percentages, arrangements, and techniques. The practical program of the presented study was based on casting (17) reinforced concrete rectangular beams with cross-section dimensions (250 * 150) mm and a length of (2150) mm have been strengthened with CFRP sheets. The one was control beam without PVA or SFRC. The remaining sixteen specimens were divided into two groups. The first group consisted of eight beams that were cast completely with PVA and SFRC materials. The second group comprised another eight beams that were cast with PVA and SFRC from the bottom layer of the beam up to a height of 52 mm. Results showed that utilizing 1.2% of PVA and 1% of steel fiber increased the maximum strength and mid-span deflection for both groups compared to the control beam. Specific values are needed the maximum increase in beam failure load was 54.3% and 47.3%, and the largest increase in the mid-span displacement of the beam was 34.14% and 27.84% for the first and second groups, respectively. The role of the proposed (PVA / SFRC) layer is to control the cracking of concrete and detain or even avoid premature debonding of the strengthening CFRP sheets. Because the (PVA / SFRC) layer’s ability to exhibit strain hardening behavior is primarily determined by the used fiber volumetric ratio, two different steel fiber volumetric ratios (fiber volumetric ratios of 0.5% and 1%, respectively) increased the maximum load in the first and second groups by 10.91% and 8.33%, respectively. Three flexural failure patterns plate-end interfacial debonding, concrete cover separation, and FRP rupture were seen in the tested specimens. The experiments demonstrated that the FRP rupture caused the BSPV 1.0.1.2 specimen to fail.