An analytical investigation focusing on the concrete damage progress of the PBL shear connector under the influence of various lateral pressures, employing a coupled RBSM and solid FEM model was carried out. The analytical model succeeded in simulating the test shear capacities and the failure modes adequately. The internal failure process was also clarified; the two horizontal cracks occurred near the top of the concrete dowels through the hole of the perforated steel plate, and afterward, the two vertical cracks also initiated and propagated along with the shear surface. In a low lateral pressure case, the shear strength was determined by the vertical cracks propagated along the shear surface. While as the amount of applied lateral pressure increased, the shear strength of the two vertical cracked surfaces was enhanced, and the shear strength of the PBL was characterized by the occurrence of the splitting cracks and caused the splitting failure into the side concrete blocks. Moreover, the combined effects of lateral pressure and hole diameters were also evaluated numerically, and it was found that the increase in shear strength was more in a large diameter case subjected to high lateral pressure because of the wide compressive regions generated around the concrete dowel.

https://www.mdpi.com/2073-4352/10/9/743/pdf

Numerical Evaluation of the Perfobond (PBL) Shear Connector Subjected to Lateral Pressure Using Coupled Rigid Body Spring Model (RBSM) and Nonlinear Solid Finite Element Method (FEM)

The flexural strength of Slender steel tube sections is known to achieve significant improvements upon being filled with concrete material; however, this section is more likely to fail due to buckling under compression stresses. This study investigates the flexural behavior of a Slender steel tube beam that was produced by connecting two pieces of C-sections and was filled with recycled-aggregate concrete materials (CFST beam). The C-section’s lips behaved as internal stiffeners for the CFST beam’s cross-section. A static flexural test was conducted on five large scale specimens, including one specimen that was tested without concrete material (hollow specimen). The ABAQUS software was also employed for the simulation and non-linear analysis of an additional 20 CFST models in order to further investigate the effects of varied parameters that were not tested experimentally. The numerical model was able to adequately verify the flexural behavior and failure mode of the corresponding tested specimen, with an overestimation of the flexural strength capacity of about 3.1%. Generally, the study confirmed the validity of using the tubular C-sections in the CFST beam concept, and their lips (internal stiffeners) led to significant improvements in the flexural strength, stiffness, and energy absorption index. Moreover, a new analytical method was developed to specifically predict the bending (flexural) strength capacity of the internally stiffened CFST beams with steel stiffeners, which was well-aligned with the results derived from the current investigation and with those obtained by others.

Flexural Strength of Internally Stiffened Tubular Steel Beam Filled with Recycled Concrete Materials.

Behaviour of rectangular concrete-filled steel tubular slender column with unequal wall thickness

The interactions within the components of L-section concrete-filled steel tube (CFT) with binding bars subjected to axial load are analyzed. By reasonably setting the effective confined areas of L-section CFT with binding bars, the L-section is divided into a square and two rectangular sections. The rectangular sections have binding bars while the square section has no one. The logical assumptions on the characters and boundary conditions of the cutting section are suggested. The constitutive relationship of confined concrete is adopted to build the equivalent constitutive relationship of the core concrete confined by L-section steel tube with binding bars and the parameters are confirmed through experimental data. The experimental specimens are calculated by the proposed constitutive relationship. The calculating results of load-strain curves are in good agreement with the experimental ones.

Constitutive relationship of l-section cft with binding bars

Cyclic behavior of concrete-filled square tubular columns with stiffened plastic hinge region

This paper describes an experimental study on the flexural and eccentric compressive behavior of concrete-filled square steel tube (CFSST) beam-columns stiffened with PBL stiffeners. Three types of CFSST beam-columns were fabricated and tested under the flexural moment and eccentric compressive load. Among the three types of columns, the two types of columns were strengthened with the PBL and steel plate stiffeners; the other type of columns was not strengthened. In addition, extensive finite element analyses (FEA) were carried out to evaluate the stress distribution. Flexural test results show that failure modes of specimens without stiffeners were different from specimens with the PBL or steel plate stiffeners. The results also demonstrate the distribution of cracks in the concrete was affected by stiffeners and the columns with the PBL stiffeners have the most uniformed crack distributions. The capacity improved by the PBL stiffeners was insignificant. However, the flexural stiffness of the specimen stiffened with the PBL stiffeners was about 20% larger than the unstiffened specimen. Eccentric compressive load test results show the capacity of specimen with the PBL stiffeners was 6.95% larger than the unstiffened specimen. The eccentric compressive capacity decreased with the increase of the eccentricity ratio or slenderness ratio. FEA results show that stiffeners can effectively improve the mechanical behavior of CFSST specimens under bending and eccentric compressive loads.

Mechanical performance of concrete-filled square steel tube stiffened with PBL subjected to eccentric compressive loads: Experimental study and numerical simulation

Zong-yuan Zhou

Papers

Mechanical performance of concrete-filled square steel tube stiffened with PBL subjected to eccentric compressive loads: Experimental study and numerical simulation