H-section Steel Beams Research Articles

Global buckling bearing capacity of corroded H-section steel beams

To understand the effect of seawater corrosion on the stability of steel beams, a global buckling bearing capacity test is conducted on steel beams corroded via an electrochemical method while considering the initial geometric imperfections. The equivalent remaining thickness of the corroded steel beam is calculated based on the yield load obtained from material property tests. Subsequently, this novel approach for calculating the corrosion thickness is utilized to establish a numerical model to simulate the global buckling bearing capacity of the steel beam. Employing this method enables a parameter analysis to be conducted. Furthermore, a new formula for the global buckling of the ultimate bearing capacity of steel beams is proposed based on the differential equilibrium equation of the microdeformation of steel members subjected to bending and torsion. The virtual work principle is employed to develop this formula, which not only simplifies the calculation process, but also assigns clear physical significance to each term.

Surface residual stress in H-section steel beams processed by quenching and self-tempering using instrumented indentation testing

Using instrumented indentation testing, we explore the measurement of surface residual stress in H-section steel beams produced through the quenching and self-tempering (QST) process. We establish a significant correlation between the plastic pile-up behavior observed during indentation and the magnitude of surface residual stress. We thoroughly clarify the distribution of plastic pile-up and residual stress, linking their variations to non-uniform phase transformation and changes in mechanical properties resulting from the QST process. Moreover, we employ an indentation curve analysis to evaluate surface residual stress, obviating the need for direct measurements of pile-up height. These findings facilitate the measurement of non-uniform surface residual stress in H-section beams, crucial for ensuring structural integrity, yet challenging to measure in situ.

Essential stressing state characteristics of H-section steel beams in fire revealed by modeling tested response data

This study finds out the essential behavior features of H-section steel beams in fire by analyzing the response data applying structural stressing state theory. Firstly, the deformation data are transformed into the generalized work of force (GWF) values called the state variables. Then, the state variables are used to build the stressing state mode and the parameter characterizing the mode called the stressing state characteristic pair. Next, the characteristic points in the evolution curve of the characteristic parameter are distinguished by the Mann-Kendall criterion. Further, the investigation into the evolution curve of the stressing state mode verifies the characteristic points. Thus, the starting points of the beams’ failure processes are revealed from the tested data and the corresponding loads are defined as the failure loads. Also, the other characteristic point called the elastoplastic branch (EPB) point is revealed from the evolution curves of the stressing state characteristic pair. Both characteristic points are the embodiment of the natural law from quantitative change to qualitative change of any system, which provides the new reference to update the analysis and design of H-section steel beams in fire. Finally, the formulas are fitted to calculate the failure loads and the EPB loads of the beams in fire with a verification.

Innovative inner sleeve composite bolted connections for modular steel constructions: Experimental and numerical studies

The application scenarios of modular steel constructions (MSCs) are becoming more and more extensive due to their exceptional advantages: minimum on-site work, and higher construction speed and quality. Inter-module connections are the critical components, which can significantly affect the integrity and seismic behavior of MSCs. This study proposed an innovative inner sleeve composite bolted connection which combines blind bolts, high-strength bolts and inner sleeve to improve the constructability and seismic behavior. Experimental tests on four full-scale cruciform connections composed of hollow structural steel (HSS) columns and H-section steel beams with different configurations were carried out under cyclic load. The failure modes, moment-rotation relations, initial rotational stiffness, ductility and energy dissipation were analyzed. GB 50011–2010 was used to evaluate the seismic performance and verify the applicability for the seismic design of the proposed connection, in which the lower limit of elastic inter-story drift ratio [θe] is 0.004 rad (or 1/250) and that of elasto-plastic inter-story drift ratio [θp] is 0.02 rad (or 1/50). The yield inter-story drift ratio, [θy] = 4.00–6.75[θe], and the ultimate inter-story drift ratio, [θu] = 1.00–2.00[θp] for the test specimens under cycle load, demonstrating the satisfactory deformation capacity and ductility. Furthermore, EC3 Part 1–8 was adopted to evaluate the stiffness characteristic of the proposed connection, indicating that the proposed connection can be classified as a “semi-rigid” and partial strength connection. Finally, refined numerical models calibrated against the experimental results were established and parametric evaluation was conducted based on the numerical models. The results demonstrate that the effect of the thickness of the inner sleeve and column in the panel zone and the diameter of the blind bolt and vertical high-strength bolt is insignificant. The presented research will provide useful references for further application and popularization of MSCs.

Seismic behaviour of novel self-tightening one-side bolted joints of prefabricated steel structures

In response to the requirements of building industrialization and sustainable development, prefabricated steel structures are vigorously promoted in recent years. The joint is an important part of prefabricated steel structures. The response of the structures under earthquake is directly determined by the seismic behaviour of the joints. Square steel tube columns and H-section steel beams are widely used in prefabricated steel structures due to the superior mechanical properties. Nevertheless, the bolted joints need to be operated on both sides. To solve this problem, a novel self-tightening one-side bolt (STOSB) was proposed based on the self-tightening high strength one-side bolt (SHSOB) developed by our research group. The behaviour and failure mechanism of the prefabricated steel structure joints based on the STOSBs under the low cyclic loading were revealed. Based on the existing experimental research, the finite element software ABAQUS was used to establish the refined numerical models of three fabricated steel joints. The numerical simulation analysis was carried out to verify the practicability of the STOSBs in practical engineering. The equivalent viscous damping ratio ζ - inter-story drift angle θ curve, hysteretic curve and skeleton curve of each specimen were obtained. On this basis, a parametric analysis was carried out to explore the effects of the column flange thickness, column diaphragm plates, endplate thickness, endplate stiffeners and other factors on the seismic behaviour of this novel joint. Subsequently, according to the moment - rotation hysteretic curves determined by the finite element analysis, a restoring force model of this novel joint under the low cyclic loading was established. The results show that the STOSBs can be used in practical engineering. The failure mode of each specimen is that a plastic hinge appears in the steel beam above the stiffeners. The endplate is always close to the column flange during the test. The seismic behaviour of the joint is significantly influenced by the endplate stiffness and column flange thickness. The bearing capacity, energy dissipation and rotational stiffness of the joint are enhanced with the endplate stiffness and column flange thickness increasing. Setting diaphragm plates in the steel column opposite to the upper and lower flanges of the steel beam can achieve similar results. When the stiffness of the endplate or column flange is weak, the moment - rotation hysteretic curve is full and the joint is a semi-rigid joint. When the stiffness of the endplate and column flange is strong, the moment - rotation hysteretic curve is in an elastic range and the joint is a rigid joint. The hysteretic behaviour of such joints under the low cyclic loading can be well simulated by the restoring force model established herein.

Seismic Retrofitting Method Using CFRP Sheets for H-Section Steel Beam with Variable Cross Section

Severe damage to steel bridge piers and steel rigid-frame piers starting from regions of abrupt change in cross section has been widely reported. Therefore, finding a simple and effective seismic retrofitting method for steel structural members with variable cross sections to improve their plastic deformation performance is currently an urgent concern. The objective of this study was to establish an effective seismic retrofitting method for H-section steel beams with abruptly variable cross sections using a carbon fiber–reinforced plastic (CFRP) sheet because of its outstanding properties such as light weight, high strength, and superior durability. Bending and bending-shear cyclic loading tests were conducted with two parameters, including the type of CFRP sheets, and whether or not polyurea putty was inserted between the CFRP sheet and steel beam. The test results indicate that the proposed retrofitting method using intermediate-modulus CFRP and polyurea putty increases the load-carrying capacity, ductility, energy dissipation capacity, and bending stiffness of H-section steel beams significantly without any failure. Further, by implementing finite-element (FE) analyses considering the actual cyclic plasticity properties of steel, anisotropic performance of the CFRP sheets, and nonlinear bond-slip properties of the polyurea putty layer, the cyclic loading test results were reproduced accurately. Moreover, in the cases in which the polyurea putty was applied, parametric FE analysis of the CFRP bonding method with and without creating a stepped length at the top of each CFRP sheet showed that the retrofitting method without the stepped length was similar in effectiveness to the method with the stepped length.

Moment capacity of H-section steel beam with randomly located pitting corrosion

The H-section steel beam is one of the most commonly used steel components in buildings, industrial structures (e.g., bridges and ocean platforms), and industrial equipment. These steel beams are inevitably subjected to corrosion, most commonly the pitting type. The moment capacity of steel beams is the most important parameter influencing the performance of steel structures. This work examines the effects of pitting corrosion on the moment capacity of H-section steel beams with random pitting corrosion. Stochastic finite element method was utilized to analyze the influence of pitting corrosion. Focus is given on the relationship between moment capacity and mass-loss ratio. Corrosion occurrences at the tensioning flange and the compression flange are investigated. A method of predicting the residual moment capacity of corroded steel beam is proposed. The proposed analytical formula can be a convenient and applicable way for estimating the moment capacity of H-section beams.

Flexural buckling behavior of corroded hot-rolled H-section steel beams

This paper mainly investigates the flexural buckling behavior of corroded hot-rolled H-section steel beams under four-point bending. A total 43 observations comprising of five experiments and thirty-eight numerical analysis results were reported to investigate the corrosion types, degrees and locations on the initial imperfections, failure modes and the flexural buckling behavior of steel beam. Based on the analysis, a recommended formula of the flexural buckling strength of corroded steel beams is derived using the direct strength method. The results show that the tested specimens fail with the local buckling of upper flange and web near the mid-span, but the failure positions and the buckling half-wavelength are different with corrosion degrees. The results also show that the yield load, buckling load and ultimate load of tested specimens decrease with the corrosion degrees increasing. When the corrosion ratio reaches 16.88%, the yield load decreases at a ratio of 21.4%, the critical buckling load decreases by 33.2%, the ultimate load after buckling decreases at a ratio of 28.3%, and the ductility coefficient decreases by 59.4%. Finally, the comparison between predicted and actual flexural strength indicates that the proposed formula can calculate the flexural buckling capacity of corroded H-section steel beams with varying degrees of corrosion.

Behavior of large-scale connections between circular concrete-filled steel tubular columns and H-section steel beams

Three large-scale connections between circular concrete-filled steel tubular columns and H-section steel beams were tested. The specimens include one connection with T-shaped stiffeners under static load and two connections, respectively, with T-shaped stiffeners and diaphragms (including interior and exterior diaphragms) under cyclic loads. During the test, the experimental phenomena were observed. The static properties of strength and ductility are calculated for static connection based on load–displacement curves, while the seismic properties of strength, ductility, and energy dissipation are analyzed for seismic connections based on hysteretic load–displacement curves. Combining experimental phenomena, mechanical properties, and stress development, the beam-hinge failure mode can be identified for all specimens. The measured beam strengths of specimens are compared with those predicted by the current AISC-360, EC4, and GB 50017-2017 codes. The study results show that all connections are reliable. A finite element model, established and verified with the experimental results, is used to perform parametric analysis. Furthermore, design suggestions of T-shaped stiffeners and diaphragms are proposed based on a parametric analysis.

Behaviour of CFST column to H-section beam connections with T-shaped vertical anchorage

Three large-scale connections between square concrete-filled steel tubular (CFST) columns and H-section steel beams were tested. T-shaped vertical anchorage was used as the embedded elements and both static and seismic behaviours of the connections were tested in this study. The experimental parameters include length and location of T-shaped vertical anchorage. Based on the experimental data, the strength, ductility, stiffness degradation, and energy dissipation of the connections were calculated. The test results show that the connections exhibit good static and seismic behaviours. Furthermore, a parametric study was conducted using the finite element method where the considered parameters include the height and depth of end anchorage, and the thickness of vertical plate. Based on the study results, a preliminary design method is proposed, which includes the design formulae for calculating the thickness of vertical plate, the thickness of end anchorage, and the punching shear capacity of concrete. In conclusion, with a proper design, the connections with T-shaped vertical anchorage can be reliably used in practical applications.

Seismic performance of bolted connection of H-beam to HSS-column with web end-plate

This paper presents an experimental study on a bolted joint for connecting H-section steel beams to square hollow structural steel (HSS) columns and connecting upper and lower HSS columns in a multi-storey prefabricated steel structure. The components within a module are welded together in the factory, and the modules are assembled on site using high-strength bolts. A rigid connection or a semi-rigid connection can be achieved by adjusting the number and size of bolts. The stiffness of semi-rigid bolted connection changes with the load. The connection is rigid during minor and moderate earthquakes, whereas during major earthquakes, the cover plate slips relative to the beam flange to dissipate energy. In this paper, model tests and finite element analysis (FEA) of the seismic performance under cyclic loads are conducted on six full-scale connections, and the results are compared with the results of a welded connection. The failure mode, slip behaviour, variation and distribution of the bolt tensions, and seismic performance of the connections, including the hysteretic behaviour, skeleton curve, ductility, rotational capacity and stiffness degradation, are obtained. The influences of the number of bolts and the thickness of cover plate on the mechanical and seismic properties are studied. The results show that a reasonable larger bolt hole can facilitate the installation and improve the ductility and energy dissipation capability without significantly affecting the load-carrying capacity of the connection. The results show that the proposed bolted connection has good hysteresis behaviour, energy dissipation and ductility. It is suitable for earthquake-resistant structures.

Interfacial behavior and debonding failures of full-scale CFRP-strengthened H-section steel beams

Strengthening existing steel beams with externally bonded carbon fiber-reinforced polymer (CFRP) plate has attracted many interests in the research community. Debonding of the CFRP plate is the dominant failure mode in a flexurally strengthened steel beam, and the debonding failure is controlled by the interfacial responses between the CFRP plate and the substrate steel beam. Although some experimental investigations have been conducted on CFRP-strengthened steel beams, limited test results on the interfacial stress and strain responses especially in full-scale steel beams, are available to verify the numerical modeling. This paper presents an experimental study on the flexural behavior of full-scale CFRP-strengthened H-section steel beams. The effects of different bond lengths of CFRP plates and the presence of steel stiffeners are investigated. The test results in terms of the failure modes, load-deflection responses, CFRP strains, interfacial shear stress distributions are reported in detail. A three-dimensional finite element model is proposed to predict the flexural performance of full-scale CFRP-strengthened steel beams, and it is then validated extensively by the test results.

Behavior of connections between square CFST columns and H-section steel beams

Three large-scale connections between square concrete-filled steel tubular (CFST) columns and H-section steel beams were tested. The specimens include one connection with continuous flange under static load and two connections with continuous flange and vertical anchor respectively under seismic loads. The static properties of strength and ductility are calculated for static connection based on load-displacement curves, while the seismic properties of strength, ductility, stiffness degradation and energy dissipation are calculated for seismic connections based on hysteretic load-displacement curves. Combining the mechanical properties, experimental phenomena and strain development, beam hinge failure mode can be identified for all specimens. The measured beam strengths of specimens are compared with those predicted by the current AISC-360, EC4 and GB50017-2003 codes. The study results show that all connections are reliable. A finite element model (FEM), developed and verified with the experimental results, is used to perform parametric analysis. Furthermore, design suggestions are presented.

The Finite Element Analysis of Overall Stability of High-Frequency Welded H-Section Steel Beam

The width-thickness ratio of high-frequency welded H-section steel beam overruns the limit of the current specification, which is bound to affect the overall stability of the structure. Based on the finite element analysis, in the working conditions of being under the pure bending and crosswise distribution load, the overall stability factors of high-frequency welded H-section steel beams were studied, and several factors with some different sections were listed, which could give some advices for the engineering designers. The results show that, the overall stability factors calculated by using the formula of code and the finite element method are very close, but the former is slightly higher than the latter. The overall stability factors could be directly calculated by using the formula of code which in the crosswise distribution load-condition, but the value should be timed reduction coefficient which is less than 1 in pure bending load-condition.

Optimization Design for Steel Structure Residence Based on the Sequential Quadratic Programming Method

In order to reduce the steel consumption for one of the steel structure residence, a kind of effective approach of optimization design to the original design is given. In this paper, steel consumption of H-section steel beams are taken as objective function, which have relatively larger proportions than others. Design variables are the beam height, web thickness, flange width and flange thickness. The strength, stiffness and stability of the steel beam are taken as constraint condition under the relevant Building Code. By using the sequential quadratic programming method, we set up optimization mathematical model for optimizing the steel structure residence, and then obtain the optimal section size of the steel beams. After the structural optimization design, the steel consumption of GL1 was reduced by 8.24%, compared with those of the original design. Relative to the original design, optimized total steel consumption was reduced by 3.29%. The approach proposed in this paper is an effective method for the optimization design of steel structure residence.

Evaluation of the Fire Resistance of H-Section Steel Columns and Beams

Building fires can cause severe damages to not only human life but also building structures. Therefore, every nation requires a building regulation related to fire in aspect of safety of human and structural stability. The structural stability under fire condition can be evaluated by the fire test defined in each nation’s standard. However, the results from the test don’t satisfy the real situations of the building such as fire loads, opening size, loading and boundary condition of structural members, and etc. Meanwhile, performance based fire engineering design is regarded as an alternative evaluation method of fire. The fire engineering method has been regarded as a more rational method than the prescriptive method in terms of accuracy and cost efficiency. Recently, the limit temperature method is regarded as the easiest fire engineering method to evaluate the structural stability under fire. To make the backbone of a specification of limiting temperature method, limiting temperatures of various structural members are required. In this paper, in order to make a database of the limiting temperatures of H-section columns and beams, fire test programs with loading were conducted and the limiting temperatures and fire resistance were derived.

Experimental Research on the New Method of Complex Reinforcement for Steel Beam

A new type of complex reinforcement method for steel structure seldom used in pratical engineering mainly due to lack of theoretic and experimental support. The experiment with this method for H-section steel beams and the results of that are introduced in this paper. The mechanical properties of the steel and CFRP material are given. The carrying capacity and the load-displacemengt curves of each specimen beams are obtained as well as the stress and strain of every feature points on the middle cross section of the beams. The results may provided reference for practical engineering.

The Behaviors Of H-section Steel Beam In Fire

In this paper, the behaviors of 14 H-section steel beams in fire are investigated. The test is carried out by use of the self-made fire-test furnace. The lengths of beams are 4200 mm and 3600 mm. The temperature field and deflection of beams in fire are measured. The effect of connection, boundary condition and axial restraint on the behaviors of steel beams is also studied. The test indicates that local buckling and lateral torsional buckling of H-section steel beams occur in fire. The behaviors of H-section steel beams in fire are influenced by connection and axial restraint. When the beams undergo a large deflection, compression force then quickly changes into tension force, which supports the beam and reduces further deflection, and the catenary action takes place. The test results in this paper may be used to guide the design of this type of steel beams in fire.

Active vibration control of flexural-shear type frame structures with smart structures using piezoelectric actuators

To apply smart structures to buildings, a new vibration control strategy is proposed for flexural-shear type frame structures with smart structures using piezoelectric actuators. Actuators are incorporated in columns, and the response of the entire structure is reduced by control of the bending moment and axial force of the columns. Combined application of these two controls is performed by arrangement of actuators. Two control strategies were tested: one involves the use of a model matching method and the other is based on control theory. Excitation tests were conducted with a four-storey frame structure with a total weight of 2000 kg and a height of 3.7 m, having H-section steel beams incorporating actuators as columns. The effectiveness of combined use of bending moment control and axial force control of columns with smart structures was confirmed.