Lateral Deformation Capacity and Plastic Hinge Length of RC Columns Confined with Textile Reinforced Mortar Jackets

This paper presents a nonlinear finite element analysis (FEA) of textiles reinforced mortars (TRM)-confined reinforced concrete (RC) columns through jacketing, under combined axial and cyclic loadings. The FEA models were validated with an experimental study in the literature that was conducted on full-scale square columns reinforced with continuous steel bars (no lap splices). Subsequently, parametric study was performed on the validated FEA models. The parameters considered include various jacket’s lengths and mortar strengths. Moreover, semiempirical models were developed to evaluate the plastic hinge length (LP) and the ultimate drift ratio of RC columns confined with TRM and FRP jackets, while considering the jacket length effect. The FEA models and experimental results were in good agreement. The finite element results revealed that the increase in the jacket length improved the lateral deformation capacity and increased the plastic hinge length linearly up to a confinement ratio of 0.2. Beyond this point, the plastic hinge length shortened as the confinement ratio raised. Moreover, mortars with higher flexural strength resulted in a slightly higher deformation capacity. However, the difference in the mortar compressive strength did not affect the ultimate lateral deformation capacity. The semiempirical models show that the average difference in the predicted LP and the ultimate drift ratio values as compared to the experimental and simulated columns was 3.19 and 16.06%, respectively.

Numerical Modelling of Reinforced Concrete Slender Walls Subjected to Coupled Axial Tension–Flexure

Under strong earthquakes, reinforced concrete (RC) walls in high-rise buildings, particularly in wall piers that form part of a coupled or core wall system, may experience coupled axial tension–flexure loading. In this study, a detailed finite element model was developed in VecTor2 to provide an effective tool for the further investigation of the seismic behaviour of RC walls subjected to axial tension and cyclic lateral loading. The model was verified using experimental data from recent RC wall tests under axial tension and cyclic lateral loading, and results showed that the model can accurately capture the overall response of RC walls. Additional analyses were conducted using the developed model to investigate the effect of key design parameters on the peak strength, ultimate deformation capacity and plastic hinge length of RC walls under axial tension and cyclic lateral loading. On the basis of the analysis results, useful information were provided when designing or assessing the seismic behaviour of RC slender walls under coupled axial tension–flexure loading.

Experimental study on seismic behavior of full scale square concrete filled steel tubular stocky columns

This study mainly presented a pseudo-static experiment on two full-scale square CFST short columns with the cross-sectional width of 600 mm under combined constant axial load and cyclic lateral load. The seismic performance of the two full-scale CFST columns were investigated. Meanwhile, the plastic hinge length of the specimens was discussed. The test results presented that the specimens suffered bend-shear failure. The local buckling of steel tube occurred at the end of the specimens and the core concrete crushed. The safety redundancy of lateral bearing capacity decreased in full-scale specimen. By the method of physical observation, the plastic hinge length Lp1 was determined mainly according to the range of the local buckling of steel tube. There had a great difference between the prediction of plastic hinge lengths by the existing calculation model and the plastic hinge lengths obtained by the test.

Flexural Behavior of Posttensioned Concrete Beams with Unbonded High-Strength Strands

This paper assesses the applicability of high-strength strands to current design codes and various existing equations. To evaluate the flexural performance of posttensioned concrete members with Grade 2400 strands, a flexural experiment was conducted on eleven specimens. Test variables included the tensile strength of strands, the number of strands, the cross-section shape, and anchorage zone reinforcement details. The test results were compared with ACI 318-19, AASHTO, and equations of Du and Tao, Naaman and Alkhari, and Harajli to evaluate the applicability of flexural strength equations for posttensioned concrete members using unbonded high-strength strands. Results indicated that the provisions of ACI 318-19 and AASHTO design codes and the existing equations underestimated the increased stress of the high-strength strands. Additionally, results demonstrate that improved equations are needed to consider the strain-compatibility model, plastic hinge length, and relationship between bonded reinforcement, concrete, and prestressing steel in posttensioned members using high-strength strands.