Abbas Rezaeian, Mona Mansoori and Amin Khajehdezfuly
Top-seat angle connection is known as one of the usual uncomplicated beam-to-column joints used in steel structures. This article investigates the fire performance of welded…
Abstract
Purpose
Top-seat angle connection is known as one of the usual uncomplicated beam-to-column joints used in steel structures. This article investigates the fire performance of welded top-seat angle connections.
Design/methodology/approach
A finite element (FE) model, including nonlinear contact interactions, high-temperature properties of steel, and material and geometric nonlinearities was created for accomplishing the fire performance analysis. The FE model was verified by comparing its simulation results with test data. Using the verified model, 24 steel-framed top-seat angle connection assemblies are modeled. Parametric studies were performed employing the verified FE model to study the influence of critical factors on the performance of steel beams and their welded angle joints.
Findings
The results obtained from the parametric studies illustrate that decreasing the gap size and the top angle size and increasing the top angles thickness affect fire behavior of top-seat angle joints and decrease the beam deflection by about 16% at temperatures beyond 570 °C. Also, the fire-resistance rating of the beam with seat angle stiffener increases about 15%, compared to those with and without the web stiffener. The failure of the beam happens when the deflections become more than span/30 at temperatures beyond 576 °C. Results also show that load type, load ratio and axial stiffness levels significantly control the fire performance of the beam with top-seat angle connections in semi-rigid steel frames.
Originality/value
Development of design methodologies for these joints and connected beam in fire conditions is delayed by current building codes due to the lack of adequate understanding of fire behavior of steel beams with welded top-seat angle connections.
Details
Keywords
Mojtaba Labibzadeh, Farhad Bostan Shirin and Amin Khajehdezfuly
This study aims to investigate the effects of using circular spirals as the longitudinal reinforcing bars on the performance of the concrete beams subjected to four-point bending…
Abstract
Purpose
This study aims to investigate the effects of using circular spirals as the longitudinal reinforcing bars on the performance of the concrete beams subjected to four-point bending load.
Design/methodology/approach
The effects of using circular spirals as the longitudinal reinforcing bars on the performance of the concrete beams subjected to four-point bending load are investigated in this study. Employing circular spirals as the main longitudinal reinforcement is a novel idea presented in this paper. In this regard, a finite element model of the beam with spiral longitudinal reinforcement was developed. After model verification, several configurations of concrete beams reinforced by longitudinal spirals were simulated under the four-point loading condition.
Findings
Obtained results showed that using the longitudinal spirals in place of the conventional longitudinal reinforcing bars can improve the bearing capacity of the concrete beam, but at the same time, increases its ductility unacceptably. In other words, the spirals reduce the initial stiffness of the beam significantly. To solve the problem, the authors decided to use the longitudinal spirals as the auxiliary bars added to the main conventional longitudinal bars in the beams. New gained results were satisfactory. By adding the longitudinal spirals to the conventional bars, not only the bearing capacity of the beam increases between 24% and 63%, but also the initial stiffness and ductility of the beam raises between 11%–29% and 3%–57%, respectively, in comparison to the corresponding beam reinforced with conventional longitudinal bars.
Originality/value
Employing circular spirals as the main longitudinal reinforcement is a novel idea presented in this paper.