H-shaped Steel Research Articles

Effective Concrete Failure Area for SC Structures Using Stud and Tie Bar Under Performance Tests.

Nuclear power plants, where steel-plate concrete (SC) structures are commonly adopted, require large-scale components to withstand significant loads, such as those caused by sudden explosions. As a result, SC modular members used in nuclear power plants must have thicker walls filled with concrete compared to standard-sized ones. These large walls also require additional components, such as tie bars and H-shaped steel sections, to reinforce adhesion and resist shear stresses. This study focuses on tie bars placed adjacent to studs and evaluates their influence on the tensile strength of wall structures. To investigate this, we conducted experimental tests using full-scale specimens, including various combinations ranging from single stud to combined stud-tie configurations. Based on the results of these performance tests, we propose a design recommendation for estimating the tensile capacity of SC structures, considering the influence of tie bars.

Study on Dynamic Factors of Damped Beam Members Under Exponential Attenuation Loading

Blast loading is characterized as an impact loading with exponential attenuation, while damping serves as an intrinsic parameter that affects the vibration effect of beam members. The linear attenuation for simplified blast loading and undamped situation for beam members is often adopted by most scholars or codes for the calculation of dynamic factors. These assumptions that do not conform to the actual situation can lead to deviations in the results of the dynamic factor. In this study, the implicit solutions for the dynamic factors of both flexible and rigid beam members were derived by the exponential attenuation loading and damping of beam members. The dynamic response verification of an H-shaped steel beam blast test was completed using LS-DYNA software. The comparison calculation of the theoretical solutions of dynamic factors in this paper with the Chinese blast-resistant design code and finite element simulation was carried out. The results show that the dynamic factor will be higher when the blast loading is simplified to linear attenuation loading for undamped beams. The shape parameter of the exponential attenuation loading and the damping ratio of beam members both reduce the effect of the dynamic factor, with the damping ratio having a more significant effect.

Performance of SRC unequal-depth beam-column irregular joint in NPP under progressive collapse

The prototype structure of this study is taken from the main shield building of nuclear power plant (NPP) conventional island facilities. Emphasis is on steel reinforced concrete (SRC) unequal-depth beam-column irregular joints, studying their resistance to progressive collapse via analysis of two 1/5 scale irregular joints. Vertical monotonic loading tests were conducted on the joints, followed by numerical simulations to analyze their mechanical properties, failure modes, and progressive collapse resistance. Experimental analyses focused on irregular joint failure modes, central column load changes with displacement, beam deformations, strain variations in critical sections, and resistance mechanism development. Finite element (FE) software modeled these behaviors and was validated against experimental data. Then, according to the various beam section depths of the connected beams, this research applied the validated numerical models to examine the load-bearing capacity of the irregular joints. The results indicate that the damage of the unequal-depth beam-column irregular joint exhibits significant asymmetric characteristics. In terms of load performance, the performance of the irregular joint depends on the component performance of the shallow beam section. Within a certain range, the greater the height difference between the various beams, the greater the joint bearing capacity, but the stability of the bearing performance deteriorates. The fracture yield of H-shaped steel significantly reduces the bearing capacity, and it is recommended to reinforce shallow beams. Providing data reference for the design of the irregular joints has important practical significance.

Establishing automatic coating paths: empirical study for steel component production

The higher the complexity and size of H-shaped steel components, the more productivity challenges a coating factory encounters, particularly when catering to the intricate demands of customer-oriented industries. The aim of this research was to devise efficient coating paths for H-shaped steel components, replacing labour-intensive manual processes. A review of the existing literature revealed methodologies involving parameter adjustment, configuration recognition and optimisation of coating paths for H-shaped steel components. Using a comprehensive database of H-shaped steel components, an algorithm was developed to identify components accurately (>90% accuracy) and subsequently streamline the coating process. Through a comparative evaluation of 99 diverse scenarios of H-shaped steel coating, the results showed an average time reduction of 24.6% compared with manual coating methods. This finding bears significance given the industry’s challenges with a scarcity of skilled labour and elevated coating expenses, both of which hinder smooth business operations for practitioners.

Axial behavior variation of 72-story concrete-filled steel tubes with different joint connections due to interface debonding considering long-term deformation of concrete core

Long-term concrete deformation including shrinkage and creep occurring seriously threats the longevity, safety and serviceability of concrete-filled steel tube (CFST) structures. In this study, numerical simulation on the variation of axial behavior of 72-story CFST structures with different joint connection details due to interface debonding considering shrinkage and creep of concrete core is carried out. Three connection details including connections with inner horizonal diaphragms only, two-direction through-beams only, and inner horizontal diaphragms combined with two-direction through-beam, are considered, respectively. Vertical loading from floors is treated as centralized vertical force applied on steel tube directly. The shrinkage of concrete core is simulated by decreasing concrete temperature. A cohesive constitutive law and a Coulomb friction model are employed to describe the interface behavior in tangential direction before and after debonding, respectively. The interaction between concrete core and steel tube in normal direction is treated as a hard contact. The concrete plastic-damage (CPD) constitutive model is used for concrete core and a plastic constitutive law is employed for the steel tube. The initiation of the interface debonding between steel tube, H-shaped steel beam flanges, inner diaphragms and concrete, the variation of the force transfer path, stress redistribution, steel tube yielding and the final failure are described in detail. Results show that the axial load-carrying capacity of each CFST structure has a decrease of 26-28% when compared with that determined by the current design code where the confinement effect is considered, and a decrease of 9-10% when compared with that determined by the current design code where the confinement effect of steel tube is not considered. Moreover, the axial stiffness decreases to 76-78% of their theoretical values when debonding is not considered. Numerical results show that the interface debonding negatively affects the long-term axial load-carrying capacity and stiffness obviously, which has not been considered in current design codes. Some comments on the design of CFST members are proposed based on the numerical simulation results.

Study on the Bending Performance of Prefabricated H-Shaped Steel Beams with Different Bolt Hole Types

This paper investigates the structural performance of a new prefabricated H-shaped steel beam assembled using high-strength bolts under three-point bending. The study evaluates four bolt hole types in five layout schemes through experimental tests. The results show that specimens with standard round holes in both the H-shaped steel and connecting plates exhibited 11% to 30% higher flexural bearing capacity compared to other hole types. Additionally, ANSYS simulations closely matched the experimental results, with a 6% difference. The research results provide important references for the design of prefabricated H-shaped steel beams with different bolt hole types, offering a practical foundation for enhancing the flexural performance of steel beam designs.

Fire Resistance Performance of Constrained H-Shaped Steel Columns with Uneven Vertical Temperature Distributions

Steel columns, which are widely used in building frameworks and spatial structures, are susceptible to capacity degradation during fires, potentially leading to the overall collapse of buildings. Existing research on the fire resistance of steel columns assumes that the temperature loads encountered by steel columns are evenly distributed vertically. However, real-world fire scenarios often feature significant vertical temperature differences. Therefore, this study comprehensively investigated these variations to derive a temperature curve that accurately represents real fire conditions. Subsequently, the fire resistance limits of steel columns were studied using this temperature curve, leading to a revised calculation formula for the critical fire resistance temperatures of steel columns. The following conclusions were drawn: (1) Nonuniform longitudinal temperature distributions are influenced by parameters such as the fire source distance, the heights of ventilation openings, and the distance between a vent and the temperature measurement point. Among them, the fire source distance has the greatest impact, with the maximum longitudinal temperature difference reaching over 500 °C. (2) Variations in the load ratio and longitudinal temperature differences alter the failure positions of steel columns, reducing their critical temperatures by up to 200 °C. (3) The revised critical fire resistance temperature formula is more accurate and safer compared with that outlined in the “Technical Code for Fire Protection of Steel Structures” (GB51249-2017). These findings offer valuable insights for the fire designs of steel columns.

Axial compressive behavior of steel-hollow core partially encased composite spliced columns

Steel-hollow core partially encased composite spliced frame beam (SHSFB) amalgamates the advantages of steel and composite structures, offering excellent deformation capacity, seismic performance, material savings, and reduced weight. These advantages are also essential for frame columns. Therefore, axial compression tests were conducted on four steel-hollow core partially encased composite spliced columns (SHSCs) and one steel comparison specimen to investigate their failure modes and compressive performance. The test results revealed that the SHSC does not fully utilize the compressive performance of the composite part under compression. Based on these experimental results, improvements were made to the configuration of SHSC, and a new type of SHSC (NSHSC) was further introduced. Finite element parameter analysis was conducted on the hollow-core partially encased composite (HPEC) short columns and NSHSCs, respectively, to investigate the confined effect on concrete in the HPEC section and the influence of different parameters on the compressive performance of NSHSC. The simulated results show that the effectively confined area of concrete in the HPEC section increases with thicker H-shaped steel flanges and narrower stirrup spacing. The compressive performance and failure modes of NSHSC are determined by the lower strength of either the steel part or the composite part. Finally, by integrating concrete confined area division and the compressive stability of variable stiffness column, the calculation method for the axial compressive bearing capacity of NSHSC was proposed. The calculated values exhibit good agreement with the simulation results.

Flexural mechanical properties of H-shaped steel-bamboo scrimber composite beams

To improve the torsional buckling resistance and enhance the load-bearing capacity and ductility of H-shaped steel beams with carbon reduction materials, the concept of combining H-shaped steel with bamboo scrimber has been proposed, in which the bamboo scrimber, an eco-friendly, lightweight, and high-strength material, promises significant structural benefits. Five full-scale specimens were designed and tested, including one H-shaped steel, two bamboo scrimber beams, and two composite beams. Additionally, further simulation tests were conducted using the verified finite element model (FEM). The experimental results revealed a remarkable increase in the ultimate bearing capacity of the composite beams by 96.5 % compared to bamboo scrimber-only beams and 72.7 % compared to steel-only beams. Meanwhile, distinct from the brittle fracture characteristics of the bamboo scrimber beams, which include instantaneous crack propagation and interlaminar cracking, the composite beams exhibited localized vertical cracks within the beam's tensile zone, effectively avoiding the torsional buckling issue of the H-shaped steel beam. The results further demonstrated that increasing the cross-sectional size of the composite beams can significantly enhance their flexural stiffness (up to 669 %), and reduce the deflection at the ultimate flexural moment. When the area of the bamboo scrimber in the cross-section was reduced with an unchanged steel profile, the initial stiffness dropped to 79 % without incurring any structural instability. Furthermore, by integrating the experimental and simulation results, a fiber element model for this composite beam structure is proposed to predict the maximum flexural moment value in the ultimate state. A corresponding calculation program was developed, and it is found that the calculated predicted ultimate flexural moment values exhibited negligible deviation from both experimental and FEM results, with AV of 1.0001, AAE of 2.21 %, and COV of 3.28 %.

Axial compressive behavior of CFRP-confined rubber concrete-encased H-shaped steel hybrid columns

The use of rubber particles as aggregate replacement in concrete production (i.e., rubber concrete) is thought to be an efficient way to dispose of end-of-life rubber products. However, the use of rubber aggregates in concrete generally leads to reduced strength and stiffness as well as early cracking in concrete. Consequently, the practical use of rubber concrete has mainly been limited to non-structural applications. In this paper, a novel compressive component, termed carbon fiber-reinforced polymer (CFRP)-confined rubber concrete-encased H-shaped steel hybrid column (FRuCSC), is proposed for the structural application of rubber concrete. This novel hybrid column consists of an external CFRP tube, an encased H-shaped steel, and rubber concrete filled in between. The axial compressive behavior of FRuCSCs was investigated through combined axial compression tests and theoretical analyses. The test results indicate that FRuCSCs with a rubber replacement ratio of no more than 50 % possess excellent axial load-carrying capacity and ductility. Owing to the confinement offered by the external CFRP tube and encased H-shaped steel, the strength and ductility of the filled rubber concrete improved significantly. Furthermore, by modifying an existing axial stress-strain model of FRP-confined rubber concrete, the axial load-strain curves and axial-lateral strain curves of FRuCSCs with a rubber replacement ratio of no more than 50 % can be accurately predicted.

Effect of assembled H-shaped steel struts with servo system on the safe excavation of a subway station

An innovative design of assembled H-shaped steel struts (AHSS) with servo system is introduced for the deep excavation of a T-shaped subway interchange station in soft soil. Analysis of the field monitored axial force of the strut, horizontal displacement of retaining wall, ground surface settlement and displacement of the nearby existing tunnel showed that the servo system could provide a convincing stable axial force for each level of AHSS. When a new level of AHSS with servo system was put into operation, the axial force of the closest level of concrete strut above tended to be more greatly affected than the other levels of strut. The first level of concrete strut contributed much less to resisting horizontal displacement of the diaphragm wall than the other levels of strut, and was under tension during the later stage of excavation. The maximum horizontal displacement of diaphragm wall, displacement of the existing tunnel and ground surface settlement were all controlled well with the operation of AHSS with servo system. Meanwhile, stricter control of the horizontal displacement of the diaphragm wall in the early stage is considered to be beneficial to the control of further deformation of the excavation at a later stage.

Investigation on axial compression performance of self-compacting fly ash concrete filled square steel tube column: Tests and numerical simulation

Self-compacting concrete has the advantages of high fluidity, high uniform density, and low porosity. To promote the engineering application of self-compacting concrete, this article studies the axial compression test of ten square steel tube self-compacting concrete columns. The effects of design parameters such as different grades of concrete strength and internal structures of circular steel tubes, square steel tubes, and H-shaped steel on the mechanical properties of self-compacting fly ash concrete filled square steel tube columns are studied. The failure mode, characteristic load and characteristic displacement, ductility, and energy dissipation capacity of each specimen are analyzed. On the basis of the test, the finite element analysis model of steel tube self-compacting concrete column is established, and the test results and simulation results are compared and analyzed. The results show that: the failure mode of the square steel tube specimen is the multilayer middle and upper ring buckling failure. Internal structural measures of square steel tube and H-shaped steel can improve the bearing capacity, ductility, and energy dissipation capacity of the specimen. It is not recommended to use the specimen with an outer square and an inner circle design. The results of the finite element simulation have a high degree of matching with the test results, which intuitively reflects the changes in force of each component.

Resilience-based seismic design and cyclic behavior of assembled joints between self-compacting concrete-filled rectangular steel tube frame columns and H-shaped steel beams

The overall stability of prefabricated steel structures depends significantly on the strong seismic resilience exhibited by the connections between beams and columns. This paper introduces a novel beam–column connection approach, referred to as the welded upper and lower flanges and two diagonal web plates (WULF-TDWP). Unlike conventional methods, this approach replaces bolted connections with butt-welded joints between steel beams and employs short cantilever beams to achieve plastic hinge displacement. The steel-column cross-section was designed with a larger aspect ratio to better absorb and distribute energy. Six full-scale specimens were subjected to cyclic loading tests to investigate the seismic performance of the WULF-TDWP system. The main test parameters included the axial load ratio, welding configuration in the node region, and presence of reinforcement plates. The specimens exhibited two distinct failure modes: plate buckling deformation and beam–column end weld tearing. The experimental results included the hysteresis curves, skeleton curves, ductility coefficients, stiffness degradation curves, and strength degradation curves of the specimens. The experimental findings highlighted the favorable hysteresis performance, load-carrying capacity, and deformation capacity of all the nodes. Additionally, the plastic hinges were observed to shift, thereby delaying the premature failure of the node region. Notably, the omission of welding between the cantilever short beam flange and steel column significantly reduced the initial stiffness of the node. Through finite element analysis, the seismic performance of the beam-column joints with upper and lower flange welded connections and cantilever short beams was elucidated. The reliability of the finite element model for assessing the seismic performance of the nodes was confirmed through validation using experimental findings. Furthermore, this paper categorizes the nodes and introduces a simplified calculation model based on the moment–rotation method.

EXPERIMENTAL STUDY ON THE WOODEN MEMBER CONNECTION METHOD IN SEISMIC PANEL DAMPERS FOR STEEL STRUCTURES

Recently, government of Japan has encouraged using forest resources to expand the use of timber. Although moderate-or large-scale buildings are generally steel constructed structures, the authors proposed using cross-laminated timber (CLT) as support members for seismic panel damper systems. The benefits of employing mass timber as support members include the effective utilization of forest resources and a reduction in the building weight. To investigate the shear transfer performance between the shear panel damper and the mass timber, 16 specimens were meticulously prepared. Based on the test results, steel types such as H-shaped steel, circular tube, cruciform steel and steel plate were shown to be effective as the shear connector. In cases where H-shaped steel, circular tubes, and cruciform steel are utilized as shear connectors, significant labor is required for welding to the H-shaped steel and cutting into the mass timber, demanding time and effort from workers. Ensuring the shear connector section has high stiffness is crucial to maintain the energy dissipation capacity of the shear panel. Steel plates offer an advantage in their flexibility to control both strength and stiffness through the size of the plate used.

EXPERIMENTAL STUDY ON THE WOODEN MEMBER CONNECTION METHOD IN SEISMIC PANEL DAMPERS FOR STEEL STRUCTURES

Recently, government of Japan has encouraged using forest resources to expand the use of timber. Although moderate-or large-scale buildings are generally steel constructed structures, the authors proposed using cross-laminated timber (CLT) as support members for seismic panel damper systems. The benefits of employing mass timber as support members include the effective utilization of forest resources and a reduction in the building weight. To investigate the shear transfer performance between the shear panel damper and the mass timber, 16 specimens were meticulously prepared. Based on the test results, steel types such as H-shaped steel, circular tube, cruciform steel and steel plate were shown to be effective as the shear connector. In cases where H-shaped steel, circular tubes, and cruciform steel are utilized as shear connectors, significant labor is required for welding to the H-shaped steel and cutting into the mass timber, demanding time and effort from workers. Ensuring the shear connector section has high stiffness is crucial to maintain the energy dissipation capacity of the shear panel. Steel plates offer an advantage in their flexibility to control both strength and stiffness through the size of the plate used.

Effect of flexural deformation on the bearing capacity of assembled H-shaped steel strut: A case study

Abnormal flexural deformation was found in one assembled H-shaped steel strut (AHSS) of an excavation project. In order to assess the effect of flexural deformation on its bearing capacity, a field axial loading test was carried out before the dismantling of the AHSS. It was found that, due to the weak region around the loading component, the horizontal and vertical displacements were larger for the monitoring points closer to the loading component. The horizontal displacements of points H3 ~ H7 all exceeded the required limit value, and the maximum descent of each monitoring point was smaller than the required limit value. Steel columns showed negligible contribution to the restrict of the horizontal displacement but relatively good vertical support of the AHSS. As compared to the condition considering normal deformation, the safety redundancies of the AHSS were all smaller when considering the abnormal deformations. The mechanism of the flexural deformation was discussed, and suggestions for avoiding such abnormal flexural deformation were given.

Axial compressive behavior of corroded H-shaped steel columns

The unpredictability of corrosion in steel structures, especially in H-section columns, is a topic that has received limited research attention. Using Monte Carlo simulation (MCS) and finite element analysis (FEA), this study investigates the effect of random pitting corrosion on H-section steel columns' ultimate bearing capacity under axial compression. In this study, MCS was employed to address the random distribution of pitting corrosion. The reliability of MCS and FEA was validated through existing literature on compression tests of H-shaped steel columns. To comprehensively assess the detrimental effects of pitting corrosion, a total of 3650 models of H-shaped columns, each exhibiting different pitting corrosion characteristics, were subjected to analysis. These models incorporated three corrosion parameters (volume loss rate, size, and depth) and two geometric parameters (slenderness and section size). A nonlinear buckling analysis was carried out to investigate the ultimate bearing capacity of the columns. The findings indicate that a volume loss rate of 20% can cause a decrease in the column's ultimate bearing capacity by approximately 50%. Furthermore, the study reveals that at equal volume loss rates, corrosion depth and slenderness significantly influence the reduction factor, while corrosion size and section size exert a minimal impact. As a result, this paper introduces a probabilistic assessment method for estimating the reduction factor in ultimate bearing capacity for H-section steel columns. Notably, with every 10% increase in the volume loss rate, the mean reduction factor in the ultimate bearing capacity decreases by approximately 0.12.

Normalized analysis of deformation for deep excavation diaphragm walls under different neighboring building conditions

This study investigates the impact of neighboring buildings on diaphragm wall deformation during deep excavation for building foundations. Prior numerical analyses predominantly utilized surface loading models, overlooking the influence of neighboring basements. Employing the finite-element method with PLAXIS 3D AE software, we assess the effects of neighboring structures on deep excavation. Our simulation adopts the top-down construction method, employing plate elements to represent diaphragm walls Temporary retaining support measures are implemented using H-shaped steel assemblies with preloaded anchors to simulate realistic excavation conditions. Neighboring building structures are accurately modeled using plate elements. Our findings reveal that the lateral displacement of the diaphragm wall varies with the depth of neighboring basements. At depths approximately half that of the excavation depth, the displacement significantly increases, reaching approximately 1.7 times the excavation depth and stabilizing thereafter. When neighboring buildings are about twice the excavation depth away, the deformation curve of the wall converges to that of "no loading," suggesting negligible influence on diaphragm wall deformation beyond this distance. Additionally, within one excavation depth, the maximum lateral displacement depth tends to be closer to the surface as the distance to the diaphragm wall decreases. Beyond a distance of one excavation depth from the diaphragm wall, the maximum lateral displacement position is approximately at the excavation face. This study significantly contributes to the comprehension of neighboring structures' influence on diaphragm walls during deep excavation, providing crucial insights for enhancing safety measures.

An Investigation on the Seismic Behavior of the End-Plate Connection between a Steel Beam and the Weak-Axis of an H-Shaped Column Using a U-Shaped Connector

The seismic behavior of the end-plate connections between a steel beam and the weak axis of the H-shaped steel column using a U-shaped connector was investigated using numerical analysis. Finite element (FE) models were established using ABAQUS 6.14 software, and the applicability of the modeling approach was verified by comparing the numerical results with the relevant experimental results. This parametric study of the joint was carried out to analyze the effects of the thickness of the U-shaped connectors, the thickness of the end-plates, the axial compression ratio of the columns, and the linear stiffness ratio of the beam to the column. The results show that the U-shaped connector set in the weak axis of the H-shaped column can form a box-shaped panel zone with the column flange and web. The volume of the panel zone and its resistance to shear deformation are increased through this connection. Finally, the recommended reasonable ranges for the thickness of the U-shaped connector, the thickness of the end-plates, the axial compression ratio of the columns, and the linear stiffness ratio of the beam to the column are proposed in this paper.

Experimental and numerical investigation of through-diaphragm in H-shaped steel beam to CFST column connections

This research proposes a cruciform through-diaphragm (CTD) for an H-shaped steel beam to concrete-filled steel tubular (CFST) column and investigates its seismic performance experimentally and numerically. The proposed connection consists of through-plates passing through the aligned slots in the panel zone and end plates directly welded to an H-shaped steel beam. This connection eliminates welding inside the steel tube for installation of the diaphragm, while providing a reliable load path from the steel beam to the CFST column. The experimental program examined the connection hysteretic behaviors, including the moment-rotation response, ductility, initial stiffness, and energy dissipation capacity. The proposed connection shows stable hysteric behavior and good energy dissipation up to a story drift up to 4 % and satisfies the AISC seismic provisions criteria for special moment connection. A finite element (FE) model was established and verified against the experimental results. The effects of concrete infill, steel tube column thickness, axial load ratio, and through-plate thickness on the hysteretic behavior of the proposed connection were investigated through parametric analysis of 24 FE models. This study provides the information on the optimized design parameters that ensures the stable seismic performance of the proposed connection that could be used in structural engineering practice.