Web Thickness Ratio Research Articles

The dynamic ultimate strength of stiffened panels under axial impact loading

ABSTRACT The dynamic ultimate compressive strength of stiffened panels under longitudinal compressive impact is studied based on the non-linear finite element method (FEM), and an empirical formula was derived based on the results. Three types of initial deflections are considered in numerical simulation. The FE procedure was validated by comparing with existing formulas and published pieces of literature. The influences of parameters, such as material yield stress, impact duration, impact shape, plate thickness ratio, plate aspect ratio, web height ratio and web thickness ratio, were investigated. The results indicate the impact duration has a significant influence on the non-dimensional dynamic ultimate strength; the geometrical parameters and material yield strength also have a certain effect. While with the same duration, amplitude and impulse, different impact shapes have little influence. The fitting accuracy of the formula was proved by a comparison between the proposed formula and FE results. And its applicability was validated by applying to real ship panels.

Novel micro-deep-hole drill with variable web thickness and flute width

This study proposes a novel micro-deep-hole drill with variable web thickness and flute width to effectively improve the problem of tool breakage and chip clogging during micro-deep-hole drilling. Firstly, the failure form and failure mechanism of micro-drill are explored by performing drilling experiments, and it is found that the torsion fracture and bending fracture are the main premature failure modes of micro-deep-hole drilling tools. The static simulation analysis of micro-drill is further conducted to investigate the influence of geometric parameters on the stiffness and strength of high-aspect-ratio micro-drill, and the results indicate that the web thickness ratio and flute width have significant effects on drill tip stiffness and spiral groove root strength. To balance the rigidity, strength and chip evacuation capability of micro-deep-hole drilling tools, the new micro-drill with variable web thickness and flute width is developed, supplemented by comparative experiments. The results confirm that the new micro-drill has better chip removal ability, greatly reduces the drilling force, torque, drill tip wear and material peeling phenomenon, and significantly enhances the machining quality of hole wall.

NUMERICAL STUDY OF FLANGE BUCKLING BEHAVIOR OF HIGH-STRENGTH STEEL CORRUGATED WEB I-GIRDERS

Steel plate girders with trapezoidal corrugated webs (TCWPGs) have been used over the last years around the world in many roadway and railway steel bridges as they can introduce several important advantages compared to flat web plate girders. The proper design of corrugated web girders depends mainly on the flexural and shear capacity of them. However, the flexural capacity is more important. Also, not many researchers studied the flexural capacity of such girders especially, when flange local buckling failure type (FLB) occurs in these corrugated web girders. In this paper, the flange local buckling behavior of steel trapezoidal corrugated web girders built up from high-strength steel (HSS) plates has been investigated to get the advantages of both the technique of corrugated web plates (CWPs) and the high-strength steel material (HSSs) together. A new numerical parametric study on four important parameters has been carried out to explain and investigate the flange local buckling behavior of high-strength steel corrugated web girders, considering mainly the influences of the flange to web thickness ratio, unsupported length of the compression flange, the corrugation angle and the initial imperfection magnitude of the compression flange on the behavior of girders with corrugated webs built up from HSSs. Using the commonly used finite element software ABAQUS, the results of the FE models have been obtained to be analyzed and discussed. Finally, some important advices have been introduced to aid the structural engineers to design such girders under flexural loading in economical manner.

Effect of Plate Slenderness on Long-Span Duplex Stainless Steel Plate Girder

The behaviour of stainless-steel material is different from that of carbon steel due to the absence of sharp yield point. In long-span stainless steel plate girder, the part of bending moment carried by the web panel causes a reduction in the shear capacity, thereby producing the M-V interaction. Plate girders are made by connecting the flange plate and the web plate. The main objective of this study is to numerically evaluate the effect of web plate slenderness and flange plate slenderness of stainless plate girder under combined bending and shear using commercial finite element software ABAQUS. The existing experimental study related to the M-V interaction of stainless-steel plate girder was used to validate the numerical model. The variation of shear force for different flange thickness to web thickness ratios were also checked to identify the best relation. This numerical study reports a critical flange thickness to web thickness ratio. Both flange plate slenderness and web plate slenderness affect the shear carrying capacity of stainless-steel plate girder under combined bending and shear.

Numerical and experimental study on the behavior of drilled flange steel beam to CFT column connections

Numerous studies conducted on different types of rigid connections such as reduced beam section (RBS) and drilled flange (DF) showed their ductile behavior. This paper evaluates the seismic performance of moment resisting connections with drilled flange (DF) beams as a simple and efficient alternative for RBS connected to concrete-filled steel tube CFT columns. Different patterns are proposed and the shear capacity of panel zone and ductility of connection are assessed to obtain the optimum case. For this purpose, the finite element Abaqus version 6.14 is used for the numerical models with the thickness ratio of beam flange to web, the type of hole and the number of holes in beam flange as the main parameters. The best arrangement of zigzag hole pattern is first determined by cyclic loading and then experimentally validated. Based on the obtained results, the type and number of holes significantly affect the ductility of connection and decrease stress concentration in the area of beam to column connection. In addition, the idea results in changing plastic hinge from the area of beam-to-column connection and panel zone to the beam in its drilled flange region and reducing the possibility of brittle failure at connection. Further, the arrangement can decrease flexural stress in the groove weld of direct beam-to-CFT column connection by 41% and increase the flexural capacity of panel zone by 31%. Furthermore, a 35% enhancement was observed in the shear capacity of panel zone by increasing the flange to web thickness ratio.

Numerical studies on full-scale steel columns under complex seismic loading

Numerical analyses using the finite element software Opensees are conducted to examine the ultimate seismic behavior of Wide-Flange steel columns used in multi-story steel frames. An OpenSees fatigue model was adopted to consider the effect of local buckling and cyclic strength degradation. The numerical model is validated with the experimental results from seven full-scale column specimens tested by the authors in an earlier study utilizing the Multiple Usage Structural Testing System (MUST). The comparisons of results include hysteretic behavior which is obtained through three cyclic tests on steel columns with two different axial load levels, and time history behaviors of four additional columns tested by pseudo-dynamic hybrid simulation with both horizontal and vertical seismic excitations. A series of parametric studies on axial load, height or width to thickness ratio of web and flange, aspect ratio of cross section, and section forms are also carried out.

Shear behaviour of single perforated lean duplex stainless steel (LDSS) rectangular hollow beams

In this work, the effect of single circular perforation in the shear behaviour of LDSS rectangular hollow beams has been presented using finite element analyses, in a systematic manner, considering a key cross sectional parameters viz., flange thickness, flange width, web thickness, shear span etc. Predominantly, the effects of single perforation size / diameter and location (along longitudinal, transverse, and diagonals) are determined with an attention on the shear load capacity (Vu/Vy), deformed shapes (or failure modes) etc. The effects of the perforation are presented parametrically in relation to web slenderness (hw/tw) and flange to web thickness ratio (tf/tw). The FE results are then compared with the newly amended stainless steel European design code (EN 1993-1-4, 2006/A1:2015) [8]. Additionally, based on the current FE understanding, new design expressions for shear buckling factor are proposed.

Shear strength of tapered end web panels

Hot rolled beams can show insufficient strength or inertia and result in the utilization of steel plate girders in the design. For cost-effective design, tapered plate girders are employed, where the depth of the end web panel is linearly varied with the panel length. In most of design codes, the shear capacity is well estimated for prismatic web panels, with reasonable accuracy. The tapered web panels, however, are lacking investigation. The objective of this numerical study is to examine the effect of different geometric parameters of tapered end web panel on the elastic shear buckling and the nominal shear strength. The geometric parameters in question are, namely: tapering angle; tapering direction; panel aspect ratio; web slenderness ratio; flange to web thickness ratio; and attachment of transversal vertical stiffeners to panel ends. The finite element method has been employed, where linear elastic buckling and nonlinear inelastic post-buckling analyses have been performed. The numerical results have been verified against classical web buckling theory, design codes, and experimental results published in the literature. Furthermore, regression analysis has been performed for the obtained results, where new design rules have been proposed for both elastic and nominal shear strength. It has been reported that tapered end web panels possess post-buckling strength that is highly dependent on the geometric parameters.

Research on the Drilling Performance of a Helical Point Micro Drill with Different Geometry Parameters.

During the micro-drilling process of stainless steel, the wear, fracture, and breakage of the micro-drill easily occur. Micro-drill geometry parameters have significant influence on the drilling performance of the micro-drill. Nowadays, the helical point micro-drill is proposed and its improved drilling performance is validated by some researchers. In this study, to analyze the effect of geometry parameters of the helical point micro-drill on drilling performance, the mathematical models of the helical flank and ground flute are proposed, and the cutting lip shape, rake angle, and uncut chip thickness are calculated using MATLAB software. Then, based on the orthogonal tests, nine kinds of micro-drills with different point angles, web thicknesses, and helix angles are fabricated using a six-axis CNC tool grinder, and micro-drilling experiments on 1Cr18Ni9Ti stainless steel are carried out. The drilling force, the burr height, and the hole wall quality are measured and observed. The results show that the point angle is the main contributing factor for the thrust force and burr height, and the web thickness is the main contributing factor for the micro hole wall quality. The increased point angle offers a larger thrust force, but gives rise to a smaller exit burr. A larger web thickness leads to a larger thrust force and burr height, and results in a poor surface quality. With the helix angle increased, the thrust force and burr height decreases, and the surface quality of micro-hole improves. The geometry parameters with a point angle 70°, a point angle of 40°, and web thickness ratio of 0.2 can used to improve the drilling performance of the helical point micro-drill.

Shear buckling strengths of web-posts in a castellated steel beam with hexagonal web openings

Shear buckling behaviors of web-post in a Castellated Steel Beam (CSB) with hexagonal web openings under vertical shear were investigated using finite element method. Through treating the upper part of the web-post as a free body under horizontal shear force, whose shear buckling strength can be calculated by the thin-plate shear buckling theory, design equations for the vertical shear buckling strength of the web-post were proposed. Parameters that affected the vertical shear buckling strength of the web-post were studied, which were the opening height to web thickness ratio h0/tw, the web-post width to web thickness ratio e/tw, the web height of Tee-section above the opening to the web thickness hf/tw, the web thickness tw and the incline angle of the opening edge α. After obtaining the vertical shear buckling strength of a CSB through finite element model, the shear buckling coefficient k can be obtained through inverse analysis. Research results showed that k decreased non-linearly with the increase in e/tw and hf/tw and it increased linearly with the increase in α and h0/tw. Practical calculating method for k was proposed based on parameter analysis results. The vertical shear buckling strength of the web-post calculated using the proposed shear buckling coefficient k agreed well with that obtained from the finite element simulation. For the proposed method was based on the elastic buckling of the web-post, it overestimated the shear buckling strength when the web-post buckled in the elastic–plastic state.

Effect of Depth and Flange to Web Thickness Ratio on Structural Behaviour of Corrugated RC Section Used in Arch Bridge

Effect of Depth and Flange to Web Thickness Ratio on Structural Behaviour of Corrugated RC Section Used in Arch Bridge

Effects of Web Height-Thickness Ratio on Longitudinal Residual Stresses of the Welded Monosymmetric I-Section

This paper descries work carried out using ANSYS finite element techniques to evaluate the longitudinal residual stress distributions of the welded monosymmetric I-section in various web height-thickness ratios. From the analysis results, it is shown that, with the web height to thickness ratio increased, the peak values of residual tensile and compressive stress in flange decrease, and the peak residual tensile stress in web decrease too, but the peak residual compressive stress increase. Meanwhile, the distribution width of residual tensile stress in flange and the distribution width of residual compressive stress in web all present increasing trends. The magnitude of the maximum longitudinal residual tensile stresses in both the flange and web reach the yield stress fy, while the maximum residual compressive stress in wide and narrow flange is close to 0.4 fy and 0.3 fy respectively, and the peak value of compressive stress in web which closes to the wide flange and to the narrow flange is about 0.4fy and 0.3fy separately. With the change of height to thickness ratio of web, the distributive width of residual tensile stress in flange or web is about 0.3 times of flange width or web height.

Slenderness limit of Class 3 I cross-sections made of high strength steel

In this paper an attempt is made to establish a more accurate slenderness limit for Class 3 cross-section welded I beams made of high strength steel. For this purpose experimental and nonlinear numerical analysis of the local stability was performed. Ten beams with different flange slenderness were tested up to failure load. The influence of other parameters, particularly web slenderness, was analysed using finite element nonlinear numerical analysis. According to the obtained results and method proposed by B. Kato (J. Construct. Steel Res. 17 (1990) 33–94) the analytical expression for demarcation between slender and semicompact I cross-sections taking into account the flange web interaction was derived. Further research work is needed to consider also the influence of the flange to web thickness ratio.