Experimental study on small eccentric compression performance of RC short columns strengthened by full lightweight ceramsite concrete

Full lightweight ceramsite concrete (FLCC) has a promising future in the field of reinforcement and retrofit, due to its excellent properties of light weight and high strength, especially when structures to be strengthened suffer from a combination of axial and bending forces. Small eccentric compression tests were conducted on RC short columns strengthened by FLCC, and compared with existing columns. Performance indices such as cracking, ultimate bearing capacity, ductility, lateral deflection, and steel bar strain were investigated for both strengthened and existing columns under the influence of load eccentricity. Moreover, the load eccentricity was extended using finite element simulation. The results indicated the following: Compared with the existing columns, cracks in the strengthened columns developed more slowly, and the failure process was significantly delayed. In addition, the old concrete and FLCC were well bonded, and the overall cooperative force was stable. The cracking load, ultimate bearing capacity, and ductility of the strengthened columns were increased by 89.1%-257.9%, 110.9%-195.8%, and 14.9%-17.8%, at different load eccentricities respectively, compared with that of the existing columns. Combining the test results and finite element simulation, an obvious linear decline relationship was obtained between the load eccentricity and the ultimate bearing capacity of the columns. Finally, a formula for calculating the compressive bearing capacity of the strengthened columns was derived, and the calculated theoretical values were in good agreement with the comparison of the tested and simulated values. This study was hoped to provide a theoretical reference in the practical application of RC columns strengthened by lightweight aggregate concrete (LWAC).