Flange Plate Research Articles

Double Low‐Yield‐Point Steel Corrugated Plates as an Innovative Damper to Improve the Behavior of CBF Braces

ABSTRACTIn this paper, an innovative damper made of low yield point (LYP) steel compound of double corrugated plate and flange plates to form an I‐shaped damper was considered parametrically and numerically. This damper pertain to easy fabrication and replacement after a severe earthquake. The proposed damper is expected to yield while elements outside the damper remain elastic. Consequently, it acts as a ductile fuse that was confirmed in this study. Results indicated that changing the damper from conventional steel to LYP steel improves the damper's performance. Because dampers with the same exhibited different responses, classification of the damper response based on the is not approritae. Of course, considering the fact that it has shear behavior with can be used in the initial design, but it is an incomplete criterion. Also, for dampers with , the ultimate strength is increased related to the from 2.64 to 4.50 times whereas for and is reached 1.35 to 3.84 times and 1.34 to 3.80 times, respectively. It confirms that on the , the most effective on the ultimate strength is obtained by changing the A36 steel to LYP steel. It should be noted that by increasing the by two to four times, the energy dissipation is enhanced 1.44 to 5.64 times for LYP dampers and 1.15 to 2.02 times for A36 dampers.

Optimization of Rotary Drilling Rig Mast Structure Based on Multi-Dimensional Improved Salp Swarm Algorithm

The mast is a critical component of rotary drilling rigs, which has a cross-section consisting of a rectangular shape formed by two web plates and two flange plates. Structural optimization of the mast is necessary to address the issue of excessive weight. The shortcomings of the traditional structural optimization algorithms are summarized as follows: the optimized steel plate thickness is a non-integer, where rounding upwards may increase the cost to a certain extent, but it can ensure the safety of the structure; rounding downwards its load carrying capacity may not satisfy the requirements, and thus a novel Salp Swarm Algorithm is proposed to solve the optimization problem. First, this study improves the initialization and update strategy in the traditional Salp Swarm Algorithm. In order to obtain a solution for engineering, an innovative multi-dimensional running comparison is carried out. Secondly, the optimization model of rotary drilling rigs is established based on the division of the working conditions. The objective function of the optimization model is to minimize the weight of the mast while considering the constraints of strength, stiffness, stability, and welding process. Finally, the proposed optimization algorithm and the established optimization model are applied to optimize the design of the mast for a rotary drilling rig. The empirical results demonstrate that the weight of the mast has been reduced by 20%. In addition, the Improved Salp Swarm Algorithm exhibits higher solution quality, faster iteration capability, and extreme stability in optimizing welded box sections compared to the conventional algorithm. The example shows that the Improved Salp Swarm Algorithm is applicable to the optimization problem of box sections.

Residual stress tests and predictive model of friction stir welded normal-strength aluminium alloy H-shaped sections

To address the challenges of difficult extrusion for super-large cross-section aluminium alloy members, pairs of T-shaped sections were proposed to be longitudinally friction stir welded (FSW) to form the H-shaped sections widely used in structural engineering. It was significantly different from the previous member forming method that one web plate and two flange plates were welded at the flange-web junctions. To understand the novel FSW-induced residual stress distributions and magnitudes in the H-shaped sections, six specimens made of 6061-T6 and 6013-T6 normal-strength aluminium alloys, including various width-to-thickness ratio and plate thickness, were tested using the sectioning method, leading to over 4000 original readings of compressive and tensile residual stresses. The analysis results showed that great tensile residual stresses were clearly concentrated within the web weld, and then rapidly descended to lower compressive stresses near the weld region, followed by approximately linear regression to zero state from the weld edge to the flange-web junction, while the flange data points were relatively scattered. The compressive and tensile residual stresses in each flange and web plate were observed to be slightly associated with the width-to-thickness ratio and plate thickness. A simplified multi-linear residual stress distribution model, including the magnitudes and ranges of constant and linear variation curves, was proposed for the FSW aluminium alloy H-shaped sections, and good accuracy and consistency were observed between the test and predicted results.

Influence of welding sequences and boundary conditions on residual stress and residual deformation in DH36 steel T-joint fillet welds

This paper aims to investigate the influence of welding sequences and boundary conditions on welding-induced residual stress and residual deformation of DH36 steel T-joint fillet welds through experimental and numerical methods. A series of typical experiments of successive and simultaneous double-sided welding conditions are conducted to explore both the magnitude and distribution of temperature field, residual stress and residual deformation. Meanwhile, thermal elastic-plastic finite element analysis based on a double ellipsoidal heat source model is performed to investigate the heat transfer and deformation mechanism during the welding process. The influencing factors are further explored to determine and quantify the residual stress and residual deformation induced by different welding sequences and boundary conditions. There is generally well agreement between the experimental and numerical results in terms of temperature field, residual stress, residual deformation and molten pool morphology. The results show that the welding sequences have an important influence on the magnitude and distribution of residual stress and residual deformation. Continuous simultaneous double-sided welding can significantly reduce residual stress and residual deformation to obtain better-quality welds. Boundary conditions have a significant effect on the distribution and magnitude of residual deformation and little effects on residual stress. Tightening the ends of the flange plate with bolts during the welding process can significantly reduce the deformation.

Experimental Study on Mechanic Behavior of Flange Joint for Steel Tube Under Axial Tension

The flange joint is an important connection in steel tube structures. In this paper, 11 groups of flange joint tests were conducted to investigate the influences of tube diameter, flange plate thickness, the distance from the bolt to the tube centroid, bolt numbers and material strength on the mechanical behavior. One of two failure modes in tests is that the excessive plastic deformation on the flange plate makes the flange plate lose the bearing capacity; the other is that the steel tube yield makes the joints fail. The results show that the calculating method for flange joint in Chinese design code is so safe that amplifying the calculating results of the code by 1.2 times would be closer to the bearing capacity of specimens. For a flange joint with different tube diameters, thickening the flange plate of thinner tube or thinning the flange plate of another tube are effective to ensure the deformations on both sides of the flange plates are equivalent. The ratio of the bearing capacity of the steel tube to that of flange plate should be greater than 1.7. And the thickness of the flange plate should be thicker than 14mm to reduce the deformation caused by cutting, drilling and welding during manufacturing.

Experiment and Analysis of a Hybrid Composite Post-tension Plate Girder

Steel plate girders have been employed as structural bridge parts since the 19th century. They are typically made up of built-up sections in the shape of I-beams. Web and flange plates withstand shear force and bending moment, respectively. However, plate girders are vulnerable to shear buckling. Shear buckling resistance is increased by adding reinforced vertical stiffeners and, in some cases, longitudinal stiffeners. Nevertheless, these stiffeners are sometimes not enough to prevent extreme shear buckling and only delay the shear buckling of slender web panels. This study investigated a hybrid composite post-tension (HCPt) plate girder by experiment and finite element (FE) analysis. The structural performance of the HCPt plate girder was tested using three specimens: a double-web plate girder, an in-fill concrete double-web plate girder and an in-fill concrete double-web plate girder with prestress. Results showed that the steel web filled with concrete presented preferable strength and behaviour to the hollow steel web because of the concrete in-fill. It had high load capacity, strength and ductility. The concrete in-fill prevented the steel web plate from buckling, and beams generally failed in a ductile manner. Applying prestressing techniques reduced deflection under external loads, increased the load-carrying capacity and enhanced its flexural behaviour by 126% compared to the double web plate girder. The failure mode was changed from web shear buckling in a double web girder to bending in a hybrid composite plate girder, with an improvement of web shear buckling by 88%. The FE analysis result showed excellent consistency with the experimental result.

Experimental and Numerical Investigation on Stress Concentration Factors of Offshore Steel Tubular Column-to-Steel Beam (STCSB) Connections

Steel tubular column-to-steel beam (STCSB) connections are critical parts in offshore structures, where complex component connections and the stress concentration are of significant concern. This study conducted stress concentration tests on welded STCSB connections and subsequently developed a finite element (FE) model for the connections, with the experimental results validating the accuracy of the model. The discussion focused on the influence of parameters such as the width-to-diameter ratio of the beam to the column, the diameter-to-thickness ratio of the column, the diameter-to-thickness ratio of the column to the beam, and the height-to-thickness ratio of the beam web on the fatigue performance. The study proposed optimization methods including the addition of stiffeners and outer flange plates. The findings indicate that optimized connection configurations can effectively mitigate stress concentration in the connected areas, thereby enhancing the structural stability and fatigue life. The width-to-diameter ratio of the beam to the column and the diameter-to-thickness ratio of the column significantly affect the fatigue performance of welded STCSB connections, with an increased width-to-diameter ratio of the beam to the column or a reduced diameter-to-thickness ratio of the column leading to a substantial decrease in the maximum stress concentration factors (SCFs). The addition of stiffeners and adjustment of the outer flange plate can improve stress concentration effects in the connection area.

Experimental study of air leakage of reinforced concrete panel with cracks

Evaluation of the leakage rate is necessary for infrastructure where hermetic performance holds critical importance. This study conducted a test to evaluate the air leakage rate of cracked reinforced concrete panels. Hollow beam specimens with an air chamber in the web were prepared to provide a relatively simple setup for airtight pressure testing under 200 kPa pressure. While testing, the lower flange of the beam specimen was subjected to tension cracking under transverse loading, and air pressure was applied to the air chamber of the beam to measure the air leakage rate through the flange plate as the magnitude of loading increased. The test variables were the differential air pressure, flange plate thickness, and reinforcement ratio. The test results showed that the leakage rate increased in proportion to the differential pressure. When the reinforcement ratio increased from 0.7 to 1.3 %, the leakage rate decreased by 90 %. When the plate thickness increased from 75 to 100 mm, the leakage rate decreased by 91 %. The analysis of the test results showed that the leakage rate was proportional to the cube of the crack width (R2 = 0.91–0.95), which agreed with existing prediction models. When the crack width at rebar location was used, the existing models showed the best predictions for test results. This result indicates that to accurately predict the air leakage rate of reinforced concrete members, the critical crack width at the location of reinforcement (i.e. the smallest crack width in the member thickness) is more important than the crack width at the member surface.

Experimental investigation of welded steel T-stub components under high loading rates

The equivalent steel T-stub approach is widely used in practice to analyse and design bolted steel joints that are otherwise complex to study. The available analytical and empirical models for characterizing the response of T-stub components are based on numerous experimental and numerical research studies. This research is mostly concerned with the pseudo-static response of the T-stub. However, natural and man-made hazards (such as earthquakes and impacts) are dynamic. Considering the strain-rate sensitivity of steel, dynamic effects may have a notable effect on structural behaviour. A limited number of studies investigated the response of steel components/joints at high loading rates with inconclusive, and sometimes conflicting, observations. Accordingly, an experimental study is undertaken to address the data shortage. A total of 57 welded steel T-stubs were tested under monotonic tension. The main test parameters included the T-stub flange plate thickness, the loading rate, and the bolt preload condition. The test data underscored the influence of the loading rate and bolt preload. Notably, at a loading rate of 50 mm/s, an average of 35% reduction in the elastic stiffness, a 5% amplification of strength, and a 22% reduction in ductility is observed compared to the reference pseudo-static loading rate. The paper discusses the test observations in detail, evaluates the findings considering past research, and assesses potential implications on design.

Wind-Induced Response Analysis and Fatigue Reliability Study of a Steel–Concrete Composite Wind Turbine Tower

Taking an actual 3MW steel–concrete composite wind turbine tower as an example, a finite element model of the tower structure was established, and static bearing capacity and dynamic time history response analyses were performed to identify the locations where the structure is prone to failure. On this basis, the fatigue lives of the turbine tower at the most unfavorable locations were predicted using linear cumulative damage theory, and the fatigue reliability at the corresponding locations of the structure was calculated using the kriging–subset simulation method. The most dangerous locations of the tower that are most prone to failure are as follows: the bottom of the leeward side of the upper steel tube, the flange of the steel tube, the bolt-hole imprinting surface of the flange, the leeward side of the transition tube, and the top of the leeward side of the concrete tube. The failure risk of the flange and bolt-hole imprinting surface of the upper steel tube is relatively high, followed by that of the transition tube. This indicates that special attention should be given to the design and daily maintenance of this part. The fatigue resistance of the tower can be enhanced by improving the strength of the flange plate or increasing the number of bolts and strengthening the transition tube.

Behavior and design of demountable and replaceable RC columns with bolted flange connections under eccentric compression

This study developed an innovative bolted flange connection for reinforced concrete (RC) columns, through which the RC columns could be removed and replaced in the event of a change in structural function or seismic damage. The detailed construction of the demountable and replaceable reinforced concrete columns with flange connection (DRCC-FC) is introduced firstly. Then the installation method and replacement requirement of DRCC-FC is presented, and the design formula for flange connection is also given. This study conducted experiments on nine DRCC specimens and one cast-in-place specimen under eccentric compression. The failure modes, loading capacity, deformability as well as strain on rebars and flange plates were investigated. Furthermore, finite element models of DRCCs were established and a parametric analysis was conducted. The effect of flange thickness, flange steel strength and length of connectors on mechanical properties was discussed. Results demonstrated that the failure modes of DRCC specimens were consistent with that of cast-in-place specimen, both of which exhibited yielding of rebars on the tensile side and crushing of concrete on the compressive side. The flange of the specimen with a low thickness appeared plasticity, and the other specimens did not show a significant deformation on the flange plates and bolts, which was favorable for the removal and replacement of the column components. The loading capacity of the DRCC specimens was slightly lower than that of the cast-in-place one, but the deformability was superior. Flange thickness is the main factor affecting the loading capacity and rotational stiffness of the flange connection. Finally, the formula for loading capacity of DRCCs related to flange thickness was presented. Comparison with the finite element and test results indicated that the calculation error of the formula is within 12%.

Plastic collapse behavior of plate to CHS connection under biaxially symmetric load

This study investigates the plastic collapse behavior of a non-diaphragm type connection with flange plates connected to a circular hollow section (CHS) column, where four flanges were joined from two orthogonal directions. The analysis was conducted using the finite element method (FEM). The focus was on determining the collapse load of the flange joint under a biaxially symmetric load from the four flanges. In an initial numerical analysis, the fundamental collapse behavior of the cylindrical wall was explored. Finite element models of CHS tubes with perfectly elasto-plastic material properties were employed. The analysis revealed that the plastic collapse mechanism of the cylindrical wall was influenced by the axial force in the transverse flanges. Prediction equations for the collapse load of the joint were formulated, assuming four representative collapse mechanisms and employing the principle of virtual work based on the numerical analysis results. Additionally, the ultimate strength of the joint, determined by the plastic collapse of the cylindrical wall, was computed using finite element models of CHS tubes with realistic hardening properties. A comparison between predictions from the equations based on perfectly elasto-plastic CHS tubes and numerical solutions through finite element analysis (FEA) of CHS tubes with realistic hardening properties validates the accuracy of the proposed prediction equations, even when applied to realistic steel tubes.

Force Performance Analysis and Numerical Simulation of Assembled Ribbed-Slab Abutments

This study investigates the structural performance of assembled rib-plate bridge abutments (ARBAs) with two different connection methods: bull leg bolt and flange connections. In addition, we explored the bending and shear performance of the connection parts and related areas to assess the damage characteristics and modes of these ARBAs. Utilizing model testing, a numerical analysis was conducted to define the force performance of the ARBA, with reference to a cast-in-place rib-plate abutment. The research results indicate that the bearing capacity and deformation capacity of the cap part of the assembled ribbed slab abutment model with cow leg connections are lower than those of the cast-in-place structure. When the structure fails, a 45° diagonal crack develops from the cross-section at the mid-span joint to the connection between the rib slab and the cap, until the concrete protective layer at the joint is crushed, exhibiting a shear failure mode. The bearing capacity of the assembly rib plate type abutment cap connected by the flange plate is basically the same as that of the cast-in-place structure, and the deformation capacity is weaker than that of the cast-in-place rib plate type abutment. The expansion of structural cracks is consistent with that of the rib plate type abutment connected by the cow leg. When the flange plate at the mid span is damaged, the contact surface between the flange plate and the concrete is pried off, resulting in the inability of the structure to continue bearing, exhibiting a shear failure mode. Through numerical simulation, taking the stress performance of the integral cast-in-place ribbed slab abutment as a reference, the assembled ribbed slab abutment connected by the flange plate is basically consistent with the integral cast-in-place ribbed slab abutment in terms of ultimate load, concrete damage, and steel reinforcement skeleton stress, and the connection device has not yet reached the yield state. The ultimate displacement is slightly weaker than that of the integral cast-in-place ribbed slab abutment. By comparison, it can be seen that the ultimate bearing capacity of the assembled ribbed slab abutment connected by the flange is basically the same as that of the cast-in-place ribbed slab abutment, and the stress performance can reach an “equivalent cast-in-place”, making it the preferred solution for the assembled abutment structure. The finite element parameter analysis of the flanged ARBA revealed that the thickness of the stiffening ribs, the number of bolts, and length of the flange plate anchoring steel plate were proportional to the ultimate load-bearing capacity of the prefabricated ARBA. In the case of no change in the structural damage mode, considering the economic benefits and load-bearing capacity of the structure, the following parameter combinations of the flanged ARBA are recommended: a thickness of 30 mm of the stiffening ribs, the number of bolts is 12, and a length of 50 cm of the length of flange plate anchoring steel plate.

Shear Test of Corrugated Web Girders with Concrete-Filled Compression Tubular Flanges Used in Buildings

Corrugated web girders with plate flanges have been widely applied in buildings and bridges due to the large shear capacity of the corrugated web (CW). However, experiments on corrugated web girders with tubular flanges are limited. Accordingly, this paper explores, through four full-scale small-size experimental tests used on buildings, the shear behavior of a type of girder formed with a CW, concrete-filled tubular flange, and bottom flat plate flange (CWGCFTF) with different CW thicknesses, wavelengths, and concrete strengths. Based on the imprecise results of one current test, a novel simple support device is proposed to improve the accuracy of the shear test of the CWGCFTF. The test results also show that the shear ratios of the tubular flange to the entire cross-section range from 15–18% when the loading reaches that of the corresponding shear stress to 80% of the shear yield strength of the CWs. Moreover, local buckling appears at the top surface of the steel tube with the CW shear buckling failure of the CWGCFTF under the shear tests. At the end, a theoretical equation of the shear ratio of the CW to the whole cross-section is derived, and a shear yield strength equation of the CWGCFTF is proposed and verified by comparisons with the test results.

Experimental study on large deflections of beam–column joints with reinforced flange plates

Web openings facilitate the passage of pipes and enable plastic hinge transfer. However, because these openings reduce the ultimate load at certain values, reinforced flange plates are introduced into the beam–column connections with web openings. In this study, five experimental specimens were constructed and tested, including one base specimen with only web openings, one base specimen with only flange plates, and three specimens with both flange plates and web openings. The failure modes, load–displacement responses, deflection shapes, and deformation capacity were mainly considered. Subsequently, after experimental verification, the thickness and length of the flange plates, as well as the position and diameter of the web openings were studied by numerical simulation. The results indicate that the catenary contribution coefficients and internal energies of the specimens with reinforced flange plates were higher than those of the base specimens. We also concluded that the optimal thickness of the flange plate is equal to that of the beam flange, and the optimal diameter is the maximum web opening that meets the specification requirements. In addition, the mechanical properties gradually increased with an increase the distance a from the web opening to the beam end for a ≤ 190 mm and then decreased for a > 190 mm.

Experimental and numerical investigation on residual stress and deformation of welded I-section curved steel beams

This paper presents an experimental and numerical investigation on welding-induced residual stresses and deformations of in-plane curved welded I-section steel beams. Two welded curved beams with different curvatures were investigated. After welding the curved beam, the residual deformations were measured by a 3D scanner. The residual stresses were subsequently obtained through a high-precision sectioning method. The effects of curvature on the magnitude and distributions of residual deformations and stresses at the specific sections were analysed with the test results. It was found that the residual deformation gradually increased from the weld region to both ends of the flange plate, and the torsion in the web plate became severe with a decrease in curvature of the curved beam. Moreover, the welding process of the curved beam was simulated using the finite element (FE) method. The developed FE model was validated against the test results, and thereafter, parametric analyses were conducted to assess the influence of welding sequence, welding speed, and curvatures of the curved beam on the welding residual stresses and deformations. The numerical results demonstrated that the residual stresses and deformations were significantly influenced by welding speeds, but the influence from curvature of the curved beam was relatively small. Finally, a reasonable welding sequence, welding speed, and curvature of the curved beams were recommended.

Shear strength of corrugated web girders with compression tubular flanges

The current paper focuses on the shear strength of corrugated web girders with compression tubular flanges (CWGCTFs) which considers the real web-flange juncture behaviour. Accordingly, the real juncture behaviour between the corrugated web (CW) and compression tubular flange in CWGCTFs used in conventional buildings is explored first. An elastic bifurcation buckling analysis is carried out using the finite element (FE) software ABAQUS for isolated CWs with different boundary conditions at their juncture with the flanges. ِAssuming that the dimensions of the generated CWs depend on those of conventional buildings, it is found that the corresponding embedment of the CW by the flanges of the CWGCTFs acts as a fixed connection. Having identified the real web-flange juncture behaviour, a large number of nonlinear FE models are generated to obtain the shear strength of the CWGCTFs taking into account the geometrical imperfection and material nonlinearities. This has been done based on a validation recently presented by the authors. The FE strengths are then compared with available shear strength predictions for CWGs with plate flanges (those of Driver et al. (2006), Moon et al. (2009), Sause and Braxtan (2011), Nie et al. (2013), Leblouba et al. (2017)) as well as on the derived shear force distribution relation for tubular flange and CW of CWGCTFs of the current authors (2022). Finally, the shear strength of CWGCTFs proposed by Leblouba et al. (2017) is modified to design the shear strength of CWGCTFs.

STEEL PLATE GIRDERS: RESIDUAL STRESSES FROM THE MANUFACTURING PROCESS

AbstractThe manufacturing process of steel plate girders generates residual stresses and geometrical imperfections in the flange and web plates that constitute them. These imperfections must respect the manufacturing tolerances that are presented in the regulation. In the present work several stages of the manufacturing process are studied, being these the thermal cutting of the plates, the assembling of the beam and the flange‐web welding process. This work is also accompanied by several results in terms of residual stresses and geometric imperfections of an experimental study and is made the confrontation of those results with the theoretical information available on the prEN 1993‐1‐14 and with the results obtained by numerical models that simulate the thermal processes of the plates cutting and welding.

Improving Productivity and Safety through Energy-Efficient Longitudinal Distortion Correction Technique Applied to I-Beam Web and Flange Plates

Improving Productivity and Safety through Energy-Efficient Longitudinal Distortion Correction Technique Applied to I-Beam Web and Flange Plates

Analysis on the Influence of Geometric Parameters of a Circular Steel Pipe with Flange Plates on Surface Settlement

Analysis on the Influence of Geometric Parameters of a Circular Steel Pipe with Flange Plates on Surface Settlement