This paper presents an experimental investigation and finite element analysis of cold-formed lipped channel columns strengthened with sleeves connected to column flanges using different patterns. Initially, the study presented the static compressive test results on eight specimens under pinned-end restraint conditions using different sleeve configurations. It is shown that sleeves have a significant influence on both the buckling modes and the ultimate strength of the specimens under axial loading conditions. Strengthening the columns with sleeves resulted in an increase in the ultimate strength under axial compression. The location and length of the sleeve had a significant effect on the ultimate capacity of the column, whereas the thickness of the sleeve had a less significant effect than the location and length of the sleeve. Furthermore, the tested specimens were numerically investigated using the finite-element program ABAQUS. The experimental results were used to verify the numerical model, and the verification showed that the numerical model closely predicted the ultimate strength and buckling behavior of the tested columns. It is concluded that the contribution of the sleeves to the strength of the columns decreased notably when the sleeves were fastened far away from the mid-height of the columns.

Uniformly disposing stiffeners on both sides of the corrugated steel plate could enhance the seismic performance of the corrugated steel plate wall. This paper addressed the shear resistance design of stiffened corrugated panels in horizontally-placed stiffened corrugated steel walls (HSCSWs). Three half-scale, one-story, single-bay specimens were fabricated and tested under lateral cyclic loads, each featuring a distinctive design for the infill plates. Grounded on the test observations and results, the influence of the arrangement of vertical stiffeners and the quantity of vertically arranged stiffeners on the hysteretic performance of HSCSWs was evaluated. Subsequently, finite element (FE) models of the specimens were constructed and verified in accordance with the test results. Based on the validated FE models, key parameters affecting the lateral load-bearing performance of HSCSWs were selected and parametric analyses were carried out. By introducing the normalized aspect ratio, design formulas were recommended for the yield shear strength and ultimate shear strength of HSCSWs. It was found that the proposed design formulas could furnish precise and safe estimations of the shear resistances for the test specimens, thereby enabling them to provide crucial reference for the design of HSCSWs.

Recently, many researches have been devoted to predicting Perforated Steel Plate Shear Wall (P-SPSW) behaviour, from which some have been able to propose resistance reduction formulas. Nevertheless, new findings have witnessed some nonconformance between the actual response of P-SPSWs and the values predicted by available closed form solutions. In this study, the possible sources of such nonconformances have been investigated and a novel formula for resistance reduction in P-SPSWs has been proposed. To this end, 28 SPSWs having 3~6 stories with aspect ratios ranging from 0.8 to 2.0, have been carefully designed according to the AISC requirements for thin infill panels. Afterwards, the SPSWs were simulated using practical infill panels and by adopting a rectangular perforation layout, the optimum perforation sizes were explored in such a way that the P-SPSW would exhibit a lateral sway similar to the original SPSW. Finally, all design parameters for SPSWs and P-SPSWs were collected in a database and used to propose some improved linear, bilinear and logarithmic formulas. A survey done on the proposed formula revealed an average absolute error less than 4% in estimating the perforation diameters, which is relatively small compared to the error margin of other formulas and, as a result, the formula in question is concluded to be a reliable tool for design purposes. Finally, the proposed formula for diagonal perforation has been successfully verified for estimating the strength reduction in an available experimentally studied single-story P-SPSW.

Many existing older reinforced concrete (RC) moment frames were originally designed only for gravity loads. These structures often exhibit poor performance under large seismic events. Among their components, corner beam-column connections are particularly vulnerable due to their unique configuration of restraint by only two adjoining beams, unlike interior or exterior connections. Additionally, these corner connections are more significantly affected by bidirectional ground motions and torsion due to plan irregularity. The objective of this study is to enhance the cyclic behavior of older corner beam-column connections using High-Performance Fiber Reinforced Cementitious Composites (HPFRCC). Experimental tests were conducted with four full scale connection specimens. The loading protocol reflecting a realistic loading condition was determined from nonlinear response history analyses. This study demonstrated that the use of HPFRCC significantly improved the cyclic behavior of corner beam-column connections.

This paper studies the seismic performance of a novel concrete-encased concrete-filled steel tube column and reinforced concrete beam composite joint. In order to gain insight into the seismic performance of the joint, a pseudo-static test was conducted on an actual engineering joint specimen with a scale ratio of 1:2. The specimen was subjected to a loading method comprising the application of a constant axial force to the top of the column and a cyclic load to the end of the column. Employing experiments and in conjunction with digital image correlation technology, the failure process and characteristics of such joints were subjected to detailed analysis, and the variation laws of the bearing capacity, deformation capacity, strength and stiffness degradation, seismic ductility and energy dissipation capacity of such joints were investigated. The results demonstrate that when subjected to a combination of constant axial pressure and lateral cyclic load, the joint exhibits a beam end bending failure mode, characterised by ductility. The maximum drift ratio reached was 5%. The joint displays excellent seismic performance when subjected to cyclic loading.

The performance of slender columns under eccentric loading is influenced by second-order effects, which can significantly reduce their flexural rigidity, stability, and ultimate capacity. While incorporating steel fibers in concrete improves strength and ductility, the impact on the flexural rigidity of slender steel fiber reinforced concrete (SFRC) columns, particularly at ultimate capacity (at the onset of buckling failure), remains underexplored. This study addresses this gap by developing a practical analytical approach to estimate the flexural rigidity of SFRC columns at buckling failure, using sectional analysis and concentric buckling behavior. To validate the proposed approach, finite element models were developed based on experimental study benchmarks. Using the validated FE models and the proposed approach, the flexural rigidity of the benchmarks was estimated and compared under various load eccentricities. The results of the approach showed strong agreement in predicting the flexural rigidity at ultimate capacity. A parametric study was then conducted to assess the influence of fiber volume fraction (ranging from 0% to 2%), slenderness ratio (ranging from 80 to 106.66), reinforcement ratio (ranging from 0.5% to 2%), concrete strength (ranging from 20MPa to 40MPa), and loading eccentricity on the behavior of SFRC columns under ultimate loading conditions. The findings highlight that the proposed analytical approach estimates the flexural rigidity of SFRC columns with a conservative error margin of 5-7%. Steel fibers enhance flexural rigidity and capacity, particularly at lower load eccentricities and fiber volumes around 1.5%, though their effect diminishes with higher eccentricities and fiber content. Increasing concrete strength, longitudinal reinforcement ratio, and slenderness ratio also improve flexural rigidity and capacity, but their influence reduces under bending-dominated conditions. Slender columns experience capacity reductions due to amplified P-Δ effects, which are partially mitigated at higher axial loads. Current codes of practice overestimate flexural rigidity at higher load eccentricities and underestimate it at lower eccentricities, underscoring the need for updated approaches that more accurately account for the effects of load eccentricity, material properties, and slenderness on column behavior.