Stresses In Steel Plates Research Articles

Investigation on activation performance of adhesive bonding connection between Fe-SMA and steel plates

Steel structures are extensively utilized in civil engineering because of their advantageous characteristics. However, cyclic loading can induce cracks in steel structures, resulting in a decline in mechanical properties and increased life cycle costs. In recent times, iron-based shape memory alloys (Fe-SMAs) have gained recognition as promising materials for structural reinforcement due to their distinct shape memory effect. The adhesive bonding connection between Fe-SMA and steel offers an efficient solution for reinforcing steel structures, enabling uniform stress transfer without introducing defects. This study investigates the influence of the geometric dimensions of Fe-SMA plates and the structural adhesive on the stress of steel plates through activation tests and finite element simulations. A multiple regression model has been proposed to describe the relationship between the size of Fe-SMA plates, structural adhesive, and the stress of steel plates. In addition, the temperature of the adhesive during activation is determined through activation tests. According to test results, a temperature distribution model for the adhesive has been developed, allowing for an accurate theoretical calculation of the adhesive softening length. The adhesive softening significantly impacts the stress distribution of the steel plate, making this model considerably valuable. This study provides valuable experimental data and a theoretical basis for the practical implementation of Fe-SMA in metal structural reinforcement.

A Study of Residual Stresses in Steel Plates Obtained by Laser Deposition Directly on a Rigid Substrate

A neutron diffraction method has been used to study residual stresses in corrosion-resistant martensitic steel AISI 410 plates of the composition (wt %): 0.15 С, 13 Cr, 1 Mn, 1 Si, and Fe for balance obtained by direct laser deposition. The plates are deposited on rigid substrates, which are commonly used in practice in the production of large parts. It has been shown that in plates of different thicknesses (2.2 and 7.4 mm) and the same length and width (70 × 30 mm), the patterns of the stress distribution curves are very close, however, the stresses in a 7.4-mm-thick plate are lower than in a 2.2-mm-thick plate. In both plates (2.2/7.4 mm), the maximum normal tensile stresses (~450/350 MPa) are induced near lateral edges of the substrate. The maximum tensile longitudinal stresses (~400/250 MPa) are induced in the middle section of the plate near the upper edge. In the middle section of a 7.4-mm-thick plate, a stress distribution over the thickness is observed: the stresses near the side surfaces are higher than in the middle section. The thickness distribution becomes more uniform by approaching the plate edges. The stress distribution pattern in plates obtained by direct laser deposition strongly depends on the rigidity of the substrate and, to a lesser extent, on the material and deposition technology.

A Study of Residual Stresses in Steel Plates Obtained by Laser Deposition Directly on a Rigid Substrate

A Study of Residual Stresses in Steel Plates Obtained by Laser Deposition Directly on a Rigid Substrate

Load transfer mechanism of precast concrete piers with demountable connections

To investigate the replacement or rehabilitation of precast concrete piers, a novel demountable steel-concrete composite connection with notched perfobond connectors was proposed for the pier-pile cap joint. In the proposed connection, a bolted mechanical connection is used to connect the longitudinal reinforcing bars and steel plate, which is bolted to the pile cap through pre-stressed anchor bolts. Pseudo-static capacity tests of two half-scale specimens were conducted with different axial compression ratios, and the experimental results were verified by nonlinear finite element analysis. The lateral force-displacement curves, failure modes of connection joint, stress of steel plates and connector-concrete slip were compared and discussed. Furthermore, the internal load transfer mechanism and characteristics were revealed. The results indicate that the precast pier with the proposed connection realizes the rapid assembly and demountability. Specimens present flexural failure, and damage appears at the bottom of the pier columns but above the steel jacket. The connection steel plates and bolted connection remain intact as expected. The stiffness, capacity and failure process in numerical analysis agree well with the experimental results. The notched perfobond connectors set on the base plates effectively transfer the force from the concrete column to the base plate, and enhance the base plate-concrete connection and bending resistance of the base plate.

Comparative analyses of a shield building subjected to a large commercial aircraft impact between decoupling method and coupling method

Comparative analyses of a shield building subjected to a large commercial aircraft impact between decoupling method and coupling method are performed in this paper. The decoupling method is applying impact force time-history curves on impact area of the shield building to study impact damage effects on structure. The coupling method is using a model including aircraft and shield building to perform simulation of the entire impact process. Impact force time-history curves of the fuselage, wing and engine and their total impact force time-history curve are obtained by the entire aircraft normally impacting the rigid wall. Taking aircraft structure and impact progress into account some loading areas are determined to perform some comparative analyses between decoupling method and coupling method, the calculation results including displacement, plastic strain of concrete and stress of steel plate in impact area are given. If the loading area is determined unreasonably, it will be difficult to assess impact damage of impact area even though the accurate impact force of each part of aircraft obtained already. The coupling method presented at last in this paper can more reasonably evaluate the dynamic response of the shield building than the decoupling methods used in the current nuclear engineering design.

Evaluation of multi-pass welding-induced residual stress using numerical and experimental approaches

ABSTRACTIn the present work the welding-induced residual stresses in steel plates, due to multi-pass welding are investigated numerically and experimentally. The transient finite element model is developed to estimate the axial residual stresses induced by butt welding. Element birth and death technique is used to simulate the welding process in ANSYS. Plates with 6 mm thicknesses are modelled by one and three passes of welding to investigate the effect of multi-pass welding on the induced residual stress. An experimental study is performed to calibrate the numerical results for both thermal and mechanical analyses. The X-ray diffraction method is used for measuring the residual stress. A good agreement is achieved between numerical and experimental results. It is concluded that, multi-pass welding has significant effects on the residual stress distribution.

Thermal stress measurement in steel plate strengthened by CFRP and aluminum alloy plates

In steel members strengthened by carbon-fiber reinforced polymer (CFRP) plates, the thermal stresses are introduced in the steel members, the CFRP plates and the adhesive layers when temperature changes because the linear thermal expansion coefficients of steel and CFRP are mismatched. As so far, the authors proposed a technique to reduce the thermal stress in steel members strengthened by CFRP plates, which involves bonding aluminum alloy plates with CFRP plates. In the proposed method, the thermal stress in steel member can be reduced so that there are negligible levels of stress in steel member when the cross sectional areas of CFRP and aluminum plates are designed to correspond to the coefficient of thermal expansion of steel, even though the thermal stresses are introduced in the CFRP and aluminum plates. In this study, to confirm the maintaining the thermal stress reduction in steel member by proposed method, thermal stress measurement in steel plate strengthened by CFRP and aluminum plates was carried out about 21 months. In this research, the thermal stress introduced in the steel plate strengthened by CFRP plates was also measured. Furthermore, to assume the thermal shear and normal (peel) stresses in adhesive layers, FE analysis with plane stress element was employed. As the result, it was shown the thermal stresses in steel plate with CFRP plate were able to calculate by using composite theory and measured temperature. Furthermore, in steel plate strengthened by CFRP and aluminum plates, the thermal stress introduced in steel plate was negligible-small through the all-season. It was found the thermal stresses in steel plate with CFRP plates as well as CFRP and aluminum plates were also estimated by using composite theory and measured temperature. In the steel plate strengthened by CFRP and aluminum plates, the thermal shear and normal stresses in adhesive layer glued to steel plate become smaller than that in the conventional CFRP bonded specimen. However, the shear stress in adhesive layers between CFRP and aluminum plates in proposed method was higher than the thermal stress in adhesive layers between CFRP plates in conventional method.

Reduction of Thermal Stress Induced in a Steel Plate Strengthened by Bonded Aluminum-CFRP Composite

In steel members strengthened with carbon-fiber reinforced polymer (CFRP) plate, thermal stresses are introduced in the steel members, the CFRP plates and the adhesive layers when temperature changes because the linear thermal expansion coefficients of steel and CFRP are mismatched. Therefore, the thermal stress caused by temperature change has to be considered when designing the repair or strengthening of a steel member with CFRP plates. With this in mind, the authors proposed a technique to reduce thermal stress in steel members strengthened by CFRP plate on both side, which involves bonding aluminum alloy plates with CFRP plates. In this proposed method, the thermal stresses in steel member can be reduced so that there are negligible levels of stress when the cross sectional areas of CFRP and aluminum plates are designed to correspond the coefficient of thermal expansion of steel, even though the thermal stresses are introduced in the CFRP and aluminum plates. So far, a thermal bending moment was not considered in the proposed method, because the steel members strengthened by CFRP-aluminum laminated plate on top and bottom sides were assumed. However, if the proposed method is applied on one side of steel member, the thermal stress in the steel member might not be reduced completely by generated thermal bending moment. Therefore, to confirm the effectiveness of the proposed method for one-sided bonding, heat tests were conducted on a steel plate with a laminated plate bonded on one side. Additionally, to verify test results and calculate the shear and peel stresses in the adhesive layers, a numerical model that used Eigenvalue analysis was proposed and applied. The tests revealed that using the proposed method to create a two-layered laminated plate consisting of CFRP and aluminum plates could not reduce the thermal stress completely in a thin steel plate. However, it was found that the thermal stress in steel plate can be completely reduced, even in thin steel plate, when the proposed method is used to create a three-layered laminated plate consisting of one CFRP plate between two aluminum plates, which when composited has a thermal bending moment equal to zero.

Elastic Analysis on Post-Local Buckling of Steel Plates in Thin-Walled Rectangular Concrete-Filled Steel Tube Columns

With the wide application of high-strength concrete and thin-wall steel tube in concrete-filled steel tube, it is essential to study the post-local buckling behavior of rectangle steel plates. Based on large deflection theory of plate, the post-local buckling behavior of steel plates in concrete-filled steel tube is analyzed in this paper. At the same time, the post-local stress of steel plates is obtained. The results indicate that the post-local buckling behavior of steel plates can be effectively utilized in large width-to-thickness ratios of steel plates.

Internal stresses in steel plate generated by shape memory alloy inserts

Neutron strain scanning was employed to investigate the internal stress fields in steel plate coupons with embedded prestrained superelastic NiTi shape memory alloy inserts. Strain fields in steel were evaluated at T=21°C and 130°C on virgin coupons as well as on mechanically and thermally fatigued coupons. Internal stress fields were evaluated by direct calculation of principal stress components from the experimentally measured lattice strains as well as by employing an inverse finite element modeling approach. It is shown that if the NiTi inserts are embedded into the elastic steel matrix following a carefully designed technological procedure, the internal stress fields vary with temperature in a reproducible and predictable way. It is estimated that this mechanism of internal stress generation can be safely applied in the temperature range from −20°C to 150°C and is relatively resistant to thermal and mechanical fatigue. The predictability and fatigue endurance of the mechanism are of essential importance for the development of future smart metal matrix composites or smart structures with embedded shape memory alloy components.

Numerical Investigation and Structural Analysis on the Springing Joint of a Steel Truss Arch Bridge

Arch springing is an important critical joint in a steel truss arch bridge, and it has a great influence on the mechanical behavior of the global structure. The adoption of a reasonable structure of the springing joint is of important significance in the design of an arch bridge. In this paper, with regard to the structure of Xinshiji Bridge, two types of arch springing were put forward. In Scheme-1, the lower chords of steel truss arch ribs are connected to the concrete piers with shear studs on the ribs and cap plates welded on the ribs at the top of concrete piers., while Scheme-2 is a integrated spring joint with a base plate on the bottom of the steel arch ribs and with reinforcing bars through the holes on the joints steel arch ribs. 3D finite element models of the two types of springing joint were established and the relative slips between the concrete and steel were taken into account in the analyses. The mechanical behavior of the concrete and the steel structure of the joints under applied loads was investigated and the analysis result showed that Scheme-2 is a relative better structure of springing joint, with less principle tensile stress in concrete and less Mises stress in steel plates.

Analysis of Hot Leveling Deformation Rate on the Residual Stress of Steel Plate

A 3D thermo-mechanical coupled model of hot leveling and cooling process of steel plate with nine rolls has been conducted with the aid of commercial non-linear FEM software. The effects of four hot leveling deformation rates on the transversal and longitudinal residual stresses of steel plate in the condition of same initial temperature distribution pattern has been analyzed. Different plastic deformation rates are obtained through the reduction change of No.2 leveler. The transversal and longitudinal residual stress distributions at different parts of steel plate are also studied. The results show that the transversal and longitudinal residual stresses increase with plastic deformation rates through hot leveling and cooling. The residual stress distribution patterns at various positions of the steel plate in the conditions of different plastic deformation rates can be confirmed quantitatively, which can provide guidance to practical determination of hot leveling plastic deformation rates.

Effects of initial condition of steel plate on welding deformation and residual stress due to welding

The effects of initial deflection and initial residual stress in steel plate on the out-of-plane deformation and residual stress due to welding are investigated from analysis results of thermal elastic-plastic FEM modeling with large deflection theory. Initial residual stress due to plate forming has very little effects on welding deformation and welding residual stress. For initial deflection, with concave profile (Type I), welding induced deformation has the same type as initial deflection and its magnitudes are small. When initial deflection is in the direction parallel to weld Une (Type II), welding induced deformation has minor variations. When initial deflection is bended in the direction normal to weld line (Type III), welding deformation was largely generated along the width direction of the steel plate. On the other hand, the variation in type of initial deflection does not affect the residual stress and plastic strain.

溶接鋼構造物の全応力測定への磁歪法の適用性に関する実験的検討

On maintenance of structures, there is a strong need to know stress condition of steel structures in use. Usually, strain gauges are used for stress measurement, but they can measure stress fluctuation only after pasting them to structures. So, stress already existed in structures beforehand cannot be measured. Stress measuring technique using the magneto-strictive effect senses magnetic field distortion by strain of steel itself. It has a possibility to measure stress already existed in structures beforehand, such as dead load stress or welding residual stress. We made experimental study on measuring stress in steel bridges using the magneto-strictive effect, and the following results are obtained. (1) Stress measuring technique using the magneto-strictive effect can measure stress in steel plates which have the same surface condition as that used in steel bridges. (2) The magneto-strictive effect has a possibility to measure welding residual stress in ‡T girder of steel bridges. (3) By using the magneto-strictive effect, it is possible to measure stress in steel with 200 μm thickness paint and to measure stress change of steel bridges during erection

Comparison of Acoustoelastic Methods to Evaluate Stresses in Steel Plates and Bars

Most of the methods for determining residual stresses inside metallic solids are destructive, which is undesirable. The ultrasonic technique provides a useful nondestructive tool in the evaluation of stresses. This work presents the application of shear and longitudinal waves in the determination of stress state in a steel bar. A bar stressed by a hydraulic system is used to simulate the effect of the tensile stress. The stresses are recorded and compared with the real value calculated using the force and the bar cross-sectional area. The comparison between the theoretical and experimental results shows that it is possible to correlate tensile stresses and velocity with both methods, although the longitudinal critically refracted LCR waves have greater sensitivity to the stress.

Fatigue behavior of composite beams with pyramidal shear connectors under repeated loading

For the designing of railway bridges with steel-concrete composite slab, it is necessary to estimate fatigue behavior of composite slabs. Regardless of the advancement of structural analytical methods, there still exist many problems in analyzing the composite slab with pyramidal shear connector. In order to clarify the fatigue properties of steel plate-concrete composite slabs, a series of fatigue test was carried out for several types of the TSC beams under various cross-section and loading conditions. The results are as follows: (1) the fatigue failure of TSC beams results from the tensile fracture of bottom steel plate and shear connectors, and (2) the converted fatigue strength of the plate for two million cycles can be estimated at 940kgf/cm2 from the S-N curves. Based on the test results, a simplified method is presented to predict stresses in steel plate and concrete under repeated loads. The calculated values agree well with the test results.

A STUDY ON INITIAL DEFLECTIONS AND RESIDUAL STRESSES IN STEEL PLATES WITH CLOSED CROSS-SECTIONAL STIFFENERS

A STUDY ON INITIAL DEFLECTIONS AND RESIDUAL STRESSES IN STEEL PLATES WITH CLOSED CROSS-SECTIONAL STIFFENERS

Determination of transient and residual thermal-hardening stresses in steel plates

Diagrams for determining weight fractions of pearlite and martensite, transient and residual thermal-hardening stresses are numerically evaluated and analysed for steel plates. Kinetics of phase transformation and the accompanying volumetric dilatation are taken into account. The diagrams enable the evaluation of proportions of individual constituents and phases, determination of relative volumetric changes due to phase transformations, and estimation of transient and residual stresses. The results are obtained and compared for Lomakin's theory and the Hildenwall model.

Computer analysis of the distribution of temperature, deformation, and stress in steel plates during quenching

Computer analysis of the distribution of temperature, deformation, and stress in steel plates during quenching