International Journal of Steel Structures最新文献

Cold-formed high-strength steel (CFHSS) has been gaining popularity in the construction industry due to its high strength-to-weight ratio. CFHSS is produced with a nominal yield strength of 460 MPa and above, in compliance with the national steel product standard, to assure safety, durability, and quality in use in construction. However, owing to the rapid global production of steel products, a wide range of steel products from different countries, described as ‘foreign steel’, have been shipped worldwide. These steel products have created an imbalance between design guidelines and product standards that differ by country, resulting in unpredictable construction outcomes. The Eurocode 3 and American Standard AISI S100 design codes of practice authorise the use of steel that fulfils the product standards for mechanical and chemical properties, as verified by testing procedure. However, existing steel product standards from Europe, America, Australia, Japan, and Malaysia only deal with steel with a tensile strength of up to 550 MPa. Hence, alternative approach to employ higher grades CFHSS in structural steel design was addressed.

The current research work insights the form and distribution of the sulphide inclusions in the steels. The deoxidation practice to the steels alter, the form and the distribution of the sulphide inclusions. In this present study, the effect of deoxidation practice on properties of low alloy and plain carbon steels done using, Aluminum (0.5–2.0 kg/T) and calcium silicide (0.5–2.5 kg/T) as deoxidants, and the comparative study of arc furnace and induction furnace is done. Ca–Si was added along with Al at the bottom of the ladle for the melt of arc furnace, whereas Al and Ca–Si were added separately to the ladle, for the induction furnace melt. The mechanism for the formation and the morphology of non-metallic inclusions were analyzed by determining the oxygen content and microstructure. From the microstructural analysis it has found that aluminium of size 40 μm in diameter produced elongated inclusions which may act as stress concentrators for originating cracks, where calcium–silicide form oxysulphides of spheroidal shape when added with 1.5 kg calcium silicide per ton of steel, which resulted in the rise in the ductility and impact properties.

Fire spreading across compartments or floors have been observed in realistic fires. However, structural responses in multi-compartment spreading fires are still not very clear. Unlike traditional studies focused on isolated compartment fires or uniform heating, this research simulates dynamic fire spread across compartments and evaluates the resulting structural behavior. A validated finite element model based on the full-scale travelling fire experiments was firstly developed using LS-DYNA. The effects of fire curve characteristics (short-hot, mid, long-cool), fire-source compartment location (corner, edge, center), and fire spread timing (simultaneous, delayed) were then systematically studied. Results show that early fire spread led to structural collapse within 160 min, while delayed fire spread extended structural stability beyond 600 min. Long-cool fires induced failure during the cooling phase, particularly in highly loaded central columns such as B2, which yielded at 153 min. Short-span beams formed catenary mechanisms with axial forces exceeding 2000 kN, while redistribution in adjacent columns amplified axial forces up to 2.4 times. This study provides quantified insights into internal force transfer, failure sequences, and collapse propagation under realistic fire conditions. By incorporating spatial–temporal fire dynamics in 3D, the proposed framework offers a significant advancement over prior work based on static, single-compartment scenarios, thereby informing robust performance-based fire design strategies.

This study examines the hydrogen embrittlement (HE) behavior of silicon steels with different microstructures and internal strains, processed through various heating treatments. Cold-rolled (CR) and annealed (AN) samples exhibited a ferritic phase, while water-quenched (WQ) and bake-hardened (BH) samples displayed a martensitic structure. CR samples had high strain from plastic deformation, whereas WQ and BH showed moderate strain from martensitic transformation. Hardness and ultimate tensile strength (UTS) increased with silicon content, with WQ and BH exhibiting the highest values and AN showing the lowest UTS but highest ductility. Hydrogen charging reduced UTS and significantly decreased fracture strain in CR, while WQ and BH experienced moderate reductions. AN samples remained unaffected. HE susceptibility correlated with diffusible hydrogen content, which was highest in CR and lowest in AN. After hydrogen charging, CR samples exhibited brittle fracture, WQ and BH showed mixed failure modes, and AN retained ductile failure. High silicon content effectively reduced HE, emphasizing its importance in developing HE-resistant silicon steels.

To serve important construction projects and scientific explorations in inaccessible areas, the fast-disassembling recycle-use steel container modular house has been proposed. It is a kind of particular frame or braced frame in which beams and columns are connected to corner joints. Connections between columns and corner joints are mostly partially rigid. Sometimes, connections between beams and corner joints are also partially rigid. To provide a calculation method for the buckling effective length factor of columns in container modular houses, 37469 column models have been analyzed. It can be observed that the buckling effective length factor of columns in container modular houses can be calculated by equations of sidesway uninhibited frame column or sidesway inhibited frame that considers the flexural stiffness released of column ends if corner-joints are rigid. Impacts of stiffness of corner-joint are simplified. The corner-joint’s stiffness requirements are found if the corner-joint can be treated as rigid. Furthermore, an equivalent beam stiffness is proposed when beam ends are partially connected with corner-joints.

To achieve high-accuracy and efficient reconstruction of the internal stress field in steel box girders using limited measurement point data, this study proposes an innovative approach. The method integrates Proper Orthogonal Decomposition (POD) with a CNN-LSTM neural network. The methodology involves two key computational phases. First, strain data from finite element simulations undergo POD. This extracts strain basis functions and the corresponding modal weights (q_{n}), transforming the reconstruction into a linear superposition problem. Next, the CNN-LSTM network establishes a mapping between Mises strain data and (q_{n}) at selected measurement points. Modal corrections to the finite element model use measured modal data, enhancing overall system accuracy. Static loading test results show that the CNN-LSTM network has superior convergence and prediction accuracy. The mean values for both MAC and PCC between predicted and theoretical values are 0.85. These findings suggest the proposed method can serve as a lightweight, real-time prediction module for stress–strain field analysis in bridge health monitoring systems.

The in-plane buckling safety of network arch bridges is studied in seven bridges according to the procedures recommended in the European bridge design codes. The safety is assessed by second order analysis with equivalent geometric imperfection. The buckling mode shape and the imperfection amplitude are established according to two different methods and varied in a parametric and a sensitivity study. It is concluded that the most appropriate method for the buckling mode shape calculation of network arches uses a geometrically nonlinear load–displacement analysis with subsequent eigenvalue analysis. Furthermore, the imperfection amplitudes obtained from the two methods of the European design codes show large differences, while the geometric imperfections measured in real bridges are in between them. If most conservative amplitude recommendations are used, the in-plane buckling may become design controlling. The amplitude should be chosen as a reasonable value between the two design code recommendations and considering the characteristics of the actual bridge.

To address the fatigue issue of U-rib orthotropic steel bridge decks under vehicle loading, a novel J-type stiffening rib (J-rib) structure is introduced. The structure consists of a vertical straight section and a bottom semi-arc, with a deck thickness and height comparable to those of the U-rib. The moment of inertia about the transverse axis is similar; however, the opening design facilitates welding and can significantly enhance the fatigue strength. Due to the asymmetric open section of the J-ribs, existing design codes do not provide adequate design methods. This study investigates a bridge deck with thickness ranging from 14 to 20 mm and a crossbeam spacing between 1500 and 3000 mm. Using ANSYS software, axial load-bearing capacity analysis was conducted to investigate characteristics such as load-bearing capacity, deformation patterns, and plastic zone distribution. A bearing capacity calculation method is proposed based on the stability theory of compression members. Furthermore, the combined compressive and flexural analysis indicate that the influence of vertical loads on the structural bearing capacity is relatively minor. Fatigue life comparisons suggest that the J-rib is theoretically expected to exhibit infinite fatigue life.

This study evaluated the structural performance of four-bolted connections (2 by 2 array) of stainless steel and carbon steel, which are expected to undergo physical changes after a fire, using existing material test data under post-fire condition to perform finite element (FE) analysis. The FE analysis model was developed to investigate the structural behavior of stainless steel and carbon steel double-shear bolted connection in a cooled state after exposure to high temperatures. The validation of FE analysis procedures was verified through the comparison of test results in the literature and analysis predictions. To examine the structural behavior of bolted connections in a cooled state following heating to four specific target temperatures, parametric FE analysis was also performed. Material models incorporating the post-fire material properties of austenitic stainless steel (corresponds to EN 1.4404) and carbon steel (corresponds to ASTM A992) tested by the previous studies were input, and the analysis was conducted under monotonic loading conditions. The target temperatures were set at 20 °C, 400 °C, 700 °C, and 1000 °C, and the structural performances of the double-shear bolted connections with block shear fracture, considering the material properties of both steels cooled in air after reaching these temperatures were compared and the strength reduction ratio between high temperatures (400 °C, 700 °C, and 1000 °C for stainless steel and 400 °C and 700 °C for carbon steel) and ambient temperature (20 °C) was recommended.

GFRP tube concrete-encased steel member is a new form of composite member. The sudden impacts threaten structural safety and service life, it is important to research the impact behavior of the member. Therefore, to investigate the effect of glass fiber orientation on the impact resistance of GFRP tube concrete-encased steel composite members with fixed-simply supported boundary conditions, a total of 30 finite element (FE) models were developed. Based on the correct finite element analysis method, the working mechanisms were revealed by analyzing the full impact process, energy conversion, bending moment, and shear force distribution. The influence of the fiber orientation on the flexural capacity was discussed. The shear force distributions at typical cross-sections were analyzed. Furthermore, the influence of fiber orientation on impact resistance under different impact locations and slenderness ratios was investigated. The results demonstrate that the fiber orientation can significantly affect the flexural capacity, the impact resistance, and the damage of the members. It is apparent that the bending moment contributed by the GFRP tube and concrete can be improved by placing the fibers along the hoop direction. The members with the range of fiber orientation (75°~90°/±60°~±75°) can effectively enhance the impact resistance, and the effectiveness increases with the development of slenderness ratios. The impact resistance is worst and the damage is severe when the fiber orientation is wrapped only in longitudinal direction. This study can provide a reference for the impact resistance design of the GFRP tube concrete-encased steel composite member.