Structural behavior of lightweight reinforced concrete columns exposure to eccentric loads at high temperature

Abstract

This paper presents an experimental investigation on the behavior of six reinforced concrete columns under elevated temperature. An expanded clay aggregate (LECA) was used in three reinforced concrete columns ,other three remain columns used natural aggregate .All RC columns have similar cross sectional dimensions of 150mm ×150 mm (width× height); and 1250mm total length. The columns were designed according to ACI Committee 318-2014 and exposed to different elevated temperatures of 400 oC and500 oC. After exposure to elevated temperature, the columns were axially loaded by compression force using an eccentricity ratio (e/h) equal to 0.5. The experimental test results demonstrated a remarkable decrease in the ultimate carrying capacity of the columns when subjected to elevated temperature. The experimental test results have also revealed that the lightweight reinforced concrete columns have more fire resistance than the normal weight reinforced concrete columns under same elevated temperature. The ultimate load capacity of LWRC columns decreases by about 6.5 % ,and 14.286 %, at elevated temperature magnitude of 400 ºC, and 500 ºC respectively, compared with the control column at ambient temperature. However, the ultimate load capacity of NWRC columns decreases by about 14.15 %,and 28.571 %, at elevated temperature magnitude of 400 ºC, and 500 ºC respectively, compared with the control column at ambient temperature.

Numerical investigation on the behavior of eccentrically loaded lightweight reinforced concrete columns at elevated temperature

“…The concrete damaged plasticity (CDP) model provided by ABAQUS was considered in the current numerical study to simulate the performance of concrete material. [14][15][16] In this mode, the plasticity and damage initiation of concrete are taken into account in the numerical model of the column assuming the compressive crushing and tensile cracking of concrete as main failure mechanisms. On the other hand, the deterioration of mechanical properties of concrete in compression and tension due to elevated temperature was accounted according to EC 4.…”

“…The stress intensity at supports and loading points was prevented by using supporting and bearing steel plates with dimensions of (150  180  20) mm (length Âwidth depth) as shown in Figure 4. To simulate the same experimental boundary condition of LWRC columns, 14,18 displacement/rotation boundary option provided by ABAQUS was employed. 15 Further, the compression load was applied as pressure load over the bottom bearing plate as conducted in the experimental tests 14 as shown in Figure 5.…”

“…To simulate the same experimental boundary condition of LWRC columns, 14,18 displacement/rotation boundary option provided by ABAQUS was employed. 15 Further, the compression load was applied as pressure load over the bottom bearing plate as conducted in the experimental tests 14 as shown in Figure 5. Furthermore, the interaction between concrete columns and reinforcement cage was simulating using embedded region interaction option provided in ABAQUS.…”

“…The load-displacement curves at different mesh sizes are shown in Figure 7. As can be seen from Figure 6, the mesh size of 20 mm gives the most accurate results compared with experimental test results of LWRC column at eccentricity ratio (e/h) of 0.5 and elevated temperature of 650 C. 14,18 Therefore, 20 mm mesh size was adopted in all simulated columns.…”

“…Validation of suggested model was ascertained by comparing numerical analysis results with the corresponding experimental test results of Al-Naqeeb. 18…”