Hot-rolled Shapes Research Articles

Experimental studies on shear behavior of steel-UHPC composite beam with hot rolled shape steel

The present study reported the findings of an experimental investigation of steel-ultrahigh performance concrete (UHPC) composite beams with hot rolled shape steel (HRSS). In order to investigate the shear behavior of HRSS-UHPC composite beams and determine the specific effects of shear span-to-depth ratios on the failure mode, ultimate shear strength and ductility, four shear tests were conducted. The test results showed that pronounced shear failure modes were observed in all specimens. The shear span-to-depth ratio significantly affected the shear behavior of HRSS-UHPC composite beams. As the shear span-to-depth ratio increased from 1.33 to 2.33, the shear resistance decreased by 30.5%. The ductility coefficient increased by 24.2% with the span-to-depth ratio increasing from 1.73 to 2.33. In addition, the measured ultimate shear capacity was compared to the current major shear design approaches, which indicated that the prediction for shear resistance by the standard AFNOR was closer to the experimental results. Finally, an analytical model for predicting the shear resistance of HRSS-UHPC composite beams was developed based on the experimental observations, current AFNOR design approach and previous theoretical method, which was in good agreement with the experimental results where the shear span-to-depth ratio ranged from 1.33 to 2.33.

Design and experimental study of hot rolled shape steel-ultrahigh performance concrete composite beam

A novel lightweight, high-strength and economical hot rolled shape steel (HRSS)-ultrahigh performance concrete (UHPC) composite beam is proposed for short- and medium-span composite bridges. Compared with traditional steel-concrete composite bridges, the new composite bridge has lower self-weight, better economic efficiency, and more constructional feasibility. The flexural and shear behaviors of the HRSS-UHPC composite beam were investigated through four-point bending tests on two scaled (1:2) specimens. The influence of shear-to-span ratio on the behaviors of the HRSS-UHPC composite specimens was revealed, including the failure mode, the crack distribution pattern, the propagating angle of diagonal shear cracks, and the development of crack width. The experimental results showed that the failure mode of the specimens, as well as the morphology of cracks and crack distribution, were strongly dependent on the shear-to-span ratio. In addition, the results of finite element analysis (FEA) and theoretical calculation also demonstrated that the bending and shear resistances of the proposed HRSS-UHPC composite bridge could meet the design requirements of Eurocode [1] at the ultimate limit states (ULS) and the serviceability limit states (SLS). In addition, the influence of concentrated load caused by heavy vehicle on the response of the designed composite bridge at ULS and SLS is also discussed. The calculation results of FE model show that the location of vehicle load (i.e. shear-to-span ratio) has a significant impact on the deformation of the designed composite bridge, internal force of cross section and stress of UHPC web.

Experimental performance of double built-up T moment connections under cyclic loading

Prequalification of the Double Split Tee (DST) connection has been conducted using hot-rolled shapes, whose availability is still limited in several countries. In addition, the range of available T web and flange thicknesses is narrow for these shapes. Thus, the use of built-up T-stubs on the DST connection seems to be a promising alternative, considering that they offer more freedom of sizing and allow a better use of the material. The experimental research reported here aimed to validate the use of built-up tees instead of hot rolled tees in DST moment connections. Four beam-to-column full-scale double built-up T (DBT) moment connections were subjected to cyclic loading following the prescribed loading history in AISC seismic provisions. The parameters varied among the specimens were the T flange thickness, the type of weld between the T flange and the stem (fillet weld or full penetration groove weld), and the column web thickness, in order to observe the most significant limit states of the connection, namely development of plastic hinges in beams, panel zone plastification, and T flange prying. The results indicate that the connection can sustain 4% drift without strength degradation, whether it is designed for T flange prying or beam hinging. In the case of the former, only limited permanent deformation of the flange is observed, while for the latter significant plastic deformation of the beam can be achieved with little or no damage of the T. The type of weld used has no significant effect on the connection performance.

Improvement in hot rolled shape defect after cold rolling

Improvement in hot rolled shape defect after cold rolling

FLEXURAL BEHAVIOUR OF LIGHT GAUGE COLD FORMED STEEL MEMBERS : COMPARISON OF IS CODE AND EURO CODE

Light – gauge steel evolved as a building material in the 1930’s and reached large scale usage only after the Second World War. In comparison with conventional steel construction, where standard hot rolled shapes are used, the cold formed light gauge steel structures are relatively new development. This paper presents a study on behaviour and economical of cold formed steel (CFS) built up channel section using different codes. This paper provides an experimental investigation for the bending strength of Cold – Formed light gauge steel plain (stiffened) rectangular sections. The test specimens were brake pressed from high strength structural steel sheets. In addition, the test strengths were compared with the design strengths calculated using the Indian Standard and Euro codes Specification for Cold –Formed steel structures. Flexural members are linear members in which axial forces act to cause elongation (stretch). The theoretical data are calculated using Indian Standard code IS 801-1975 and the section properties of the specimens are obtained using IS 811-1975. The specimens are designed under uniformly distributed loading with simply supported condition. The research project aims to provide which code of practice given more economical, high bending strength, more load carrying capacity and high flexural strength. The studies reveal that the theoretical investigations limit state methods (SI method) have high bending strength, high load caring capacity, maximum deflection and minimum local buckling& distortional buckling compare to the other codes.

Prevention of crack formation in the production of welded ring preforms from hot-rolled shapes of aging nickel alloys

The negative features of the active process of production of welded ring preforms from hot-rolled shapes of aging nickel alloys are considered. The mechanical characteristics of alloy EP693-VD in tensile tests of bar specimens in different conditions (initial, after air hardening, and after water hardening) are determined. An improved process is suggested, where the disadvantages are removed.

Laser-Fabricated Structural Shapes for New Construction, Overhaul, and Repair

Increasingly, fabricated structural shapes are replacing hot-rolled shapes in new vessel construction. Designed for high structural efficiency, these custom shapes can be made from materials not available in hot-rolled form. Although most production is carried out at present using conventional welding and cutting processes, high-power industrial laser processes are being developed. A recent project, titled Laser Fabricated Shapes for Naval Applications, has started the task of developing a laser-based comprehensive system for the cutting and welding of structural shapes, as well as qualifying the laser welding process and the product of the process. It is expected that the use of laser cutting and welding will allow dramatic improvements in accuracy, quality, and productivity. While the greatest application will be in the new construction arena, custom-fabricated shapes can have beneficial impact on overhaul and ship alteration projects. Aspects of system integration, product design, production, inspection, and cost issues are explored.

Laser-Cutting and Welding of DDG-51 Structural Shapes

The application of high-power industrial lasers to the production of structural shapes for shipbuilding has been analyzed. Requirements for T-and I-sections used in a DDG-51 class vessel were used to evaluate a cost/benefit ratio for fabricating shapes vice purchasing hot rolled sections. Results of the study indicate that fabricated shapes offer significant tangible and intangible benefits to the shipbuilder, and that the entire shipset of T's and I's can be cut from plate and welded to actual net shape for less cost than the purchase price of stock lengths of hot-rolled shapes. Savings from elimination of complex layout and cutting operations further add to the benefit. The high speed and high accuracy of modern industrial lasers makes possible an efficient, flexible, and cost-effective approach to the production of structural shapes. A further benefit is the potential to design a ship with structurals having the same depth, vastly improving the speed of outfitting such as the installation of piping, wireways and vent runs.

STRENGTH CHARACTERISTICS OF CHANNEL BEAMS UNDER WARPING AND TWIST PREVENTION

The fundamental bending strength characteristics of channel section beams are studied by a numerical analysis and checked with respect to the effects of loading conditions, type of cross sections and initial imperfections. The slender type of high depth channel to be likely used in plate girder structures and the compact section type for hot-rolled shapes are adopted here. Mainly emphasized are the effects of prevention of twist at the loading point and the warping restraint at beam ends. The reduction of bending strength due to lateral-torsional buckling is significantly improved by the end warping restraint and prevention of twist at the loading point. Finally, it is concluded that the channel section beams can be used as main structural members.

Improvement in the rolling of special shapes

The Omutninsk Metallurgical Plant has collaborated with the rolling laboratory at the Dneprodzerzhinsk Industrial Institute to improve the pass system on a mill which rolls billets for the production of shapes measuring 36 x 20 mm in cross section. The steel 45 shapes are made in small lots (25-30 tons) and are shipped in cold-worked state with a surface finish corresponding to precision class B (GOST 1051-73). To achieve the required surface quality and dimensional accuracy, the technology provides for hot rolling of a 38 x 22 mm billet and its subsequent drawing to the finished shape. On a semicontinuous 300/280 mill which includes a continuous four-stand 300 group and a open three-stand 280 group the hot-roUed shape is obtained from a 52-mm-square billet in seven passes: f ive passes on a smooth roll and two traverse edging passes. Here, the draft is 1.18. To reduce the number of passes, eliminate manual labor, and increase dimensional accuracy, we designed a pass system which uses a four-rol l finishing pass. This makes it possible to obtain a shape of the correct geometry in the minimum number of passes, regulate the grooves in two mutually perpendicular directions, and create a stress state which is close to cubic compression. The partings of the passes are vertical, while the gap size is 0.5 mm. In the leader pass, the corner sections have been blunted by levels with an angle of 45 ~ in order to prevent overfilling of the finishing pass. Here, the diagonals of the leader pass are equal to the diagnosis of the finishing pass, with allowance for the blunting of the corners. The rough shape is obtained by reducing the billet on the smooth roll and in a box pass. The draft in this system is 1.34. The pass system was tested in the continuous four-stand 300 group of the 300/280 mill at the Omutninsk combine, the last stand of the mill having been replaced by a four-rol l stand designed by the Dneprodzerzhinsk Industrial Institute. The four-rol l pass was created by two driven horizontal rolls 315 mm in diameter and two undriven vertical rolls 135 mm in diameter. The dimensions of the shape were within the tolerance. The fluctuation in the dimensions of ihe hot-rolled shape was connected with inaccuracies in the dimensions of the initial semifinished product, the temperature difference, and the change in the tension of the product over its length. After drawing of the hot-rolled shape, the finished product corresponded to the requisite dimensions. Compared to the existing technology, the new rolling technology makes it possible to obtain the specified shape in fewer passes while eliminating manual labor during the actual rolling operation.

Mastering the production of economical hot-rolled shapes for different sectors of industry in the XII Five-Year Plan

Mastering the production of economical hot-rolled shapes for different sectors of industry in the XII Five-Year Plan

Yield Line Analysis of Column Webs with Welded Beam Connections

In welded construction the connections, for the most part, are easily designed and fabricated. However, one of the more difficult connections occurs when a beam must be welded to a column web. This is so for two reasons: (1) analyzing the column webs capacity is arduous and (2) making the actual connection in accordance with the design is no simple task because of the space restrictions imposed on the welder by the column flanges. This paper will deal only with the first consideration—analyzing the column web strength—using Yield Line Analysis. The Yield Line approach has been utilized previously by Abolitz and Warner1 for brackets welded to column webs, and by Blodgett for welding rolled sections to box columns. The assumptions used here differ somewhat from those of the above authors. The final result is a series of curves covering a very high percentage of restrained beam to column web connections involving hot rolled shapes. The curves relate beam moments to column web thickness for a series of beam sizes and for W14 columns with yield strengths of 36 and 50 ksi. For special cases not covered by these curves, but for which the yield line pattern assumed is valid, direct solutions may be developed by use of the formulas used to construct these curves.