International Journal of Steel Structures最新文献

The traditional structural design process of rural buildings requires a lot of trial calculations and iterations of modelling work. However, rural buildings are subject to construction costs and cannot be professionally designed and checked by designers like urban buildings. Their safety and economy are difficult to meet the requirements. Therefore, an intelligent design concept of rural light steel frame structure was proposed, including intelligent modeling and intelligent optimization. Based on the automatic layer recognition method and optical character recognition technology, the BIM intelligent modeling method of rural light steel frame structure corresponding to the standard atlas of rural buildings was proposed, including layer recognition, axis text data extraction, primary selection and automatic arrangement of components. The intelligent modeling results basically met the requirements of practical application. Based on the proposed two-stage genetic algorithm, an intelligent optimization method of rural light steel frame structure was given. The optimization speed was fast and the optimization effect was good. The proposed intelligent design method was verified by practical case. The results showed that the proposed intelligent design concept of rural light steel frame structure was feasible. Compared with the traditional manual design method, the design period could be shortened by more than 80%, and the structural design indexes were comparable.

In this study, a building steel structure that adopted an equivalent shear beam structure model is analyzed, with the updating effects on this simplified analysis model discussed using sensitivity-based and artificial neural network (ANN) methods. Due to the limitations of the sensitivity-based structural model updating method, mean absolute relative error was used to evaluate the reasonable number of hidden layer nodes of the ANN multi-layer perceptron architecture to be applied to the updating equivalent shear beam structural model. A National Earthquake Engineering Research Center (Taipei) steel test structure was selected as the case study. The results reveal that the equivalent shear beam structural model updated modal parameter analysis of lower-order modes is more consistent with the modal test than the 3D finite element analysis. A comparison between the discrepancies between the sensitivity-based and ANN methods suggests that the latter outperforms the former, as indicated by its better performance in terms of predicting the first two modal natural frequencies. This finding demonstrates the applicability of the updated equivalent shear beam model and indicates that structural dynamic response analysis can be conducted using the updated stiffness values of each floor. Therefore, this simplified analysis model could be applied to the vibration analysis and design of multi-story structures (e.g., high-rise steel structures, scaffoldings, and vibrating shaking tables). Furthermore, these findings indicate that this simplified analysis model for multi-story structures could also be applied to the evaluation of old structures.

To assess the seismic performance of buildings reinforced by steel moment frames using built-in or external indirect joints, shear strength of indirect joints to be applied to computer-aided structural numerical models is required. However, Korea’s earthquake provisions do not provide the specified shear strength of indirect joints of specific seismic strengthened methods. In this study, an experiment was conducted to investigate the shear strength of indirect joints in the built-in and external seismic strengthened methods with specific indirect joints. It was confirmed that the shear strength of the indirect joint was determined to be a conservative value among the interfacial shear force of the post-installed anchor and the shear strength of the load transfer part. It was also confirmed that the indirect joint exhibited the same shear strength regardless of the type of seismic reinforcement, and the shear strength of the indirect joint was provided. In addition, a method of calculating the shear strength depending on the number of load transfer parts and the thickness of indirect joints was proposed.

This study presents designing the conventional braces with (+) shaped cross-sections as buckling restrained braces (BRB) with friction and frictionless surfaces without a gap. In this context, cyclic axial loading tests were carried out on seven braces members (one was a reference brace and the others had an outer casing and mortar). In addition, numerical models of the specimens were created and analysed with ANSYS. The core brace members were confined by two different types of steel profiles (SHS and CHS series) for the design. Each series consisted of three specimens separately. The specimen of reference and core of BRBs was a (+)-shaped section brace. In the experimental study, while a natural friction surface was preserved between the brace-steel outer casing in the first specimen of the series, a frictionless surface was created in the second. In the third specimen of the series, the gap between the core-steel outer casing was filled with mortar. The performance of the specimens was evaluated depending on the axial load capacity, hysteric behaviour and ductility. Compared to the reference in the unfilled specimens, the tensile strength increased by 3.4–6.0%, while this increase was 22.4–32.0% in the mortar-filled specimens. When the axial load capacities were considered, the increases were 268.3 and 249.8% in the mortar-filled specimens. On the other hand, mortar-filled specimens reached the highest axial load capacity. While there is an increase in energy ductility, it might be said that there is a decrease in general ductility in all specimens because of early failures. It had been observed that the lateral-torsional buckling effect of the (+) section has a direct effect on the failure mechanism.

This study aimed at developing desirable column cross-sections that are part of mid- and high-rise steel-precast concrete hybrid module buildings. Column cross-sections comprising existing modular frames are mostly steel hollow structural sections. These closed column cross-sections make the assembly process more difficult, leading to reduced constructability, and are costly because of the necessity for fireproofing treatment. In the present study, to overcome these limitations, an asymmetric open cross-section was produced by bending a steel plate, and part of it was filled with concrete. For the evaluation of the structural performance of the developed design, a total of nine specimens of asymmetric open cross-sections were experimented. The test variables were the length of the columns and eccentricity of the load. It was found that the strength decreased as the length of the column increased, and the eccentricity decreased the strength by about 45% compared to the case of central load.

The mechanical properties of corrugated steel pipe culverts (CSPCs) for highways depend on the elastic modulus of the foundation soil, the backfill height, and the culvert parameters. Evaluating the stress and deformation characteristics is crucial for the design of CSPCs. A three-dimensional finite element model and field test were used to investigate the effect of various parameters on the earth pressure and deformation of the CSPC during construction. The finite element method results were compared with the test results, and the stress and deformation characteristics of the CSPC were analyzed in detail. As the wavelength increases, the CSPC experiences more deformation, and the earth pressure at the top of the pipe decreases. When the wavelength and thickness are fixed, the displacement of the CSPC decreases, and the earth pressure at the top of the pipe increases with an increase in the wave height of the CSPC. When the wave height and wavelength are fixed, the deformation of the pipe culvert decreases, and the earth pressure at the top of increases with an increase in the pipe culvert’s thickness. These results provide new insights into the construction, design and maintenance of CSPCs.

Austenitic S30408 stainless steel exhibits good low-temperature resistance and good welding performance. This steel is often used in liquefied natural gas stainless steel storage tanks. During the construction process, the tank wall is primarily connected by butt weld joints. Because welded joints are easily affected by temperature, low-temperature weld cracking can reduce the safety of structures. To study the cryogenic mechanical properties of austenitic S30408 stainless steel welded joints at low temperatures, the low-temperature mechanical properties of austenitic S30408 stainless steel base metal and welded joint components were studied by tensile tests from − 60 to 20 °C and scanning electron microscopy analysis of fractures at various temperatures. The results show that when the temperature decreases, the stress–strain curve of base metal components changes from a power function type to an inverted "s" type; in addition, secondary hardening occurs. The yield strength and tensile strength of the welded joint and base metal increased with decreasing temperature, and the elongation and reduction of area decreased. The plastic deformation capacity of the welded joint was significantly lower than that of the base metal, and there were obvious inclusions in the microstructure.

The research project was carried out to estimate the robustness of flat steel-framed structures in a selected accidental situation. For this purpose, a multistage approach based on experimental tests and numerical analysis was performed. As the main objective of the work, a numerical dynamic analysis of the steel frames was performed under a sudden and gradual internal column loss scenario. FEA models were created in Abaqus software using solid and shell elements. Computer analyzes were carried out in a number of different cases, taking into account the size of the structure, the type of joints, and the method of removing the column from the structure. Detailed results on the axial forces and rotation of the joints under analysis are presented, and the robustness of the structures is estimated. In all cases of frames with flush end-plate joints, an insufficient level of robustness was observed and failures of the structures were obtained. In the cases of application of extended end-plate joints in frame analysis, the required level of robustness was reached in all cases and the stop of collapse was obtained. Finally, practical recommendations for designing robust joints and the whole frame structure are presented.

Fire resistance steel maintains strength at high temperatures and its allowable temperature is higher when compared with generic steel. Thus, it is needed to analyze its fire resistance quantitatively. In this study, high temperature creep tests of fire resistance steel specimens were conducted with variables of stress ratio and temperature to analyze their mechanical properties and behavior at a fire. The creep limit temperature of the Steel New (SN) steels observed from the high temperature tests was below 538 °C. The FR (Fire Resistance) steels showed stable creep behavior until 600 °C and maintained lower level of deformation for a longer period of time when compared with what was observed from previous studies. It is deduced that the FR steels are very effective in resisting deformation at high temperatures. As stress ratio increased, strain increased almost tenfold. Since strain increased very rapidly approximately from 1%, it is required not only to compare difference in final strain but also to quantitatively analyze creep behavior when strain is 0.5–1% and build up critical deformation data.

The formation of steel–concrete composites using individual steel and concrete elements is commonly ensured by two different connection techniques at connected interface level: mechanical connectors and structural adhesives. Among these two connection techniques, the use of structural adhesive for bonding steel and concrete elements is rapidly increasing; primarily owing to uniform transfer of stresses over the entire bonded area. The behaviour of bonded connection with change in adhesive bond layer thickness at the level of composite interface are analysed using finite element analysis under static loading to examine the ultimate strength and shear stresses. The failure governing parameters of bonded connections, such as engendered stresses in terms of von-mises and hydrostatic stresses at bearing ends of the composite interface along with changes in failure patterns (from adhesive to cohesive) are discussed. Also, the maximum engendered stresses along the failure plane for different bond layer thicknesses are examined. In case of one mm bond layer thickness the variation in shear stresses is very high along (39.28 MPa to 23.15 MPa) and perpendicular (34.62 MPa to 16.97 MPa) to the loading direction. While, the specimen with three mm thickness exhibits maximum load bearing capacity, it also has relatively smaller variation in shear stresses along (34.91 MPa to 21.72 MPa) and perpendicular (32.72 MPa to 17.20 MPa), which shows uniformity of stresses with increase in thickness. However, a further increase in the thickness of the bond layer results in reduction in the shear capacity of the specimen.