Seismic retrofitting of built-up battened columns through CFRP wrapping and grouting

Built-up battened columns have been widely used in steel structures mainly because of providing a higher moment of inertia than solid sections with a similar weight. However, previous earthquakes and recent studies have demonstrated the poor seismic performance of these columns. This study proposes a strengthening method for deficient built-up battened columns through chord grouting and wrapping with carbon fiber-reinforced polymer (CFRP). Experimental works and numerical simulations were employed to demonstrate the efficiency of the proposed method. The experimental works included quasi-static cyclic testing of four strengthened built-up battened columns with different batten spacing and chord distances. A comparison was made between the experimental results of the strengthened columns and four similar un-retrofitted built-up battened columns. Besides, the ABAQUS program was used to simulate 54 built-up battened columns with various batten spacing, chord distances, axial stresses, CFRPs layers, and strengthened panels. The results indicated that the proposed method prevented the buckling and bulging of flange and webs, respectively. Besides, the retrofitted columns exhibited a larger lateral strength and displacement capacity.