Abstract
For non-seismically designed columns with insufficient strength and flexural stiffness, intense inter-story drift can be incurred during a strong earthquake event, potentially leading to the collapse of the entire building. Existing strengthening methods mainly focus on enhancing axial or flexural strength but not the flexural stiffness of columns. In response, a novel direct fastening steel jackets that can increase both flexural strength and stiffness is introduced. This novel strengthening method features straightforward installation and swift strengthening as direct fastening is used to connect steel plates together to form a steel jacketed column. This new connection method can quickly and stably connect two steel components together by driving high strength fasteners into them. In this paper, the design procedure of RC columns strengthened with this novel strengthening method is originally proposed, which includes five steps: (1) estimating lateral load capacity of damaged RC columns; (2) determining connection spacing of steel jacket; (3) estimating the lateral load capacity of strengthened RC column; (4) evaluating the axial load ratio (ALR) of strengthened RC columns; and (5) estimating effective stiffness of strengthened RC columns. Lastly, an example is presented to illustrate the application of the proposed design procedure.
Highlights
The first five above mentioned deficiencies may result in insufficient flexural strength, which can be mitigated by various available strengthening techniques such as Reinforced concrete (RC) jacketing [11,12], steel jacketing [13,14]
On the basis of comparisons between predicted and measured effective flexural stiffness, the expressions recommended in EN 1994-1-1 [30] are advised to calculate effective flexural stiffness: Ki = ( EI )s + 0.6( EI )c where (EI)s is the flexural stiffness provided by the steel jacketing; and (EI)c is the flexural stiffness provided by the RC column
V ≤ Vcap,stren ≤ 0.6Vstren where V is the lateral load demand acting on the RC column; Vcap,stren is the lateral load corresponding to the moment capacity of the strengthened RC column; and Vstren is the shear strength of the strengthened RC column which is determined by the following expression: Vstren
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. To restore the seismic capacity of columns to their undamaged state, both flexural stiffness and strength must be improved. This new strengthening sembled by either welding or bolting) is developed (see Figure 2) This new strengthening straightforward installation and rapid direct method offersoffers straightforward installation and rapid as directas fastening is ing method method offers straightforward installation andstrengthening, rapid strengthening, strengthening, as direct fasfastening is used to connect steel plates together to form a steel jacketed column. The strengthening tening is used to connect steel plates together to form a steel jacketed column. Previous experimental and theoretical studies on shear connections joined by direct fastening, axial load strengthening and the seismic strengthening of RC columns strengthened by direct fastening steel jackets are first reviewed.
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