Strengthening of Fire-Damaged Reinforced Concrete Short Columns Using GFPPECC Composites
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RESEARCH ARTICLE-CIVIL ENGINEERING
Strengthening of Fire‑Damaged Reinforced Concrete Short Columns Using GFPPECC Composites P. Bhuvaneshwari1 · K. Saravana Raja Mohan1 Received: 7 February 2020 / Accepted: 12 July 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract The study investigated the strengthening effect of glass fiber and polypropylene fiber-based engineered cementitious composites (GFPPECC) on fire-damaged reinforced concrete short exterior columns. Both moderate (500 °C) and high (900 °C) intensities of fire load corresponding to the ISO834 fire curve were adopted. A total of 15 columns (150 mm × 150 mm × 1000 mm) were cast. The columns were grouped as control column (CC), unstrengthened column-(C2, C3), and strengthened column(C1, C4) with three columns in each group. The columns in group CC were subjected to axial compression up to failure and kept as the standard reference. The columns in the group (C2, C4) and (C1, C3) were fired up to 900 °C and 500 °C, respectively. Compressive loading on C2 and C3 was applied without any strengthening technique. C1 and C4 were repaired and strengthened using GFPPECC. A similar group of columns, namely unstrengthened-(A-C2, A-C3) and strengthened(A-C1, A-C4) columns, were analyzed numerically using ANSYS. The parametric analysis was carried out from experimental and numerical results. Variations between experimental and numerical results were negligible. The strengthening has restored to about 68% of the stiffness of columns damaged due to moderate fire intensity. The energy absorption, ductility, and modulus of elasticity were also good, with only about less than 10% reduction compared to the control column. The performance of columns shows that the GFPPECC composite was utilized effectively without any debonding. Whereas for high fire intensity, the GFPPECC composite was not fully used, and premature failure has occurred due to the softening of concrete at high temperatures. Keywords Short columns · ISO834-thermal load · Strengthening · GFPPECC composites · Axial loading · Parametric analysis
1 Introduction 1.1 General Worldwide the standard construction material used is reinforced concrete. Due to low thermal conductivity, concrete structures do not undergo any significant deterioration or collapse when subjected to fire loading. Therefore, repair and retrofit of these fire-damaged structures are preferred rather than to rebuild them. Strengthening for the decline of the structures subjected to elevated temperature is necessary. The concrete cover on the properties of reinforced concrete flexural members exposed to fire was tested [1]. It has * P. Bhuvaneshwari [email protected] 1
School of Civil Engineering, SASTRA Deemed University, Thanjavur 613401, India
been concluded that bottom cover concrete has a significant influence on thermal load and proposed an equivalent cover concrete for thermal resistance. A single equation for stress–strain behavior of fire-damaged (100 °C-800°C) siliceous aggregate concrete was developed
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