Richard Redwood

Design of steel and composite beams with web openings

Abstract Composite or non-composite steel beams containing large web openings are considered. A general method of analysis suitable for design use is presented and related to a number of previous studies. Comparisons are made with the results of experimental research. Detailing of reinforcement and other design considerations are summarized; the material presented provides all the information necessary for design.

BEHAVIOUR OF AXIALLY LOADED TUBULAR V-JOINTS

Abstract The results of an experimental test program comprising seven tubular V-joints and five tubular T-joints consisting of circular hollow sections and subject to branch axial loading are reported. The tested specimens had branch-to-chord diameter ratios varying from 0·22 to 0·65, and chord radius-to-thickness ratios of 13 to 23. The angle between branches of the V-joints was 60, 90 or 120 degrees. The behaviour of the joints is examined through a comparison of ultimate strengths, stiffness characteristics and hotspot stresses of comparable T and V specimens. Addition of a loaded out-of-plane branch member to a T-joint increases the strength of the T-joint when the angle between the branches is low, and decreases it when the angle is large.

ORTHOTROPIC BRIDGE DECKS WITH CLOSED STIFFENERS - ANALYSIS AND BEHAVIOUR

Abstract The behaviour of stiffened bridge decks is investigated. The deck is treated not as an equivalent continuum but as a monolithic unit in which all the interactions are considered. A rectangular shell finite element is developed which is suitable for the idealization and efficient analysis of closed type stiffeners. Solutions are compared with three experimental tests of closed type stiffeners of trapezoidal shape. These and other examples show excellent agreement with the analysis. An investigation of the effect of one of the principal parameters entering the problem is presented. This concerns the rib spacing for torsionally stiff ribs, and results obtained indicate that present design methods are conservative in some areas, but are slightly unconservative in others.

Web Post Buckling in Castellated Beams

Publisher Summary This chapter provides an overview of castellated beams. These were originally developed in an era of high materials costs and low labor costs. Subsequent increase in the cost of labor greatly reduced their competitiveness; recently, however, the potential for automated fabrication has again made them a viable product. A series of light beams is now produced in the USA that has the potential for use as castellated beams, and because of their light weight, their use as castellated beams leads to greater web slenderness than previously considered for these beams. As a result, a study was conducted on the behavior of such webs with particular attention paid to the buckling of the web-post. This chapter describes a study of noncomposite castellated beams along with some preliminary results of tests on composite castellated beams. The tests are described are those in which castellated beams are subjected to load at low moment-to-shear ratio thus, precipitating web-post buckling. There is a greater susceptibility to buckling when the beam contains a mid-depth plate welded between the upper and lower sections. The test loads are compared with the results of finite element analysis and acceptable correlation is demonstrated. The chapter describes preliminary results of tests on composite castellated beams.

Design and Behaviour of Eccentrically Braced Frames with Flexural Links

Publisher Summary Provisions for the design of eccentrically braced frames (EBF) are established in the design standards of a number of countries in seismically active regions. The design philosophy is to provide a ductile link in the beams, which is detailed so, that it dissipates energy by inelastic bending or shearing deformations, the rest of the structure remaining elastic. The link is formed either by the bracing being connected eccentrically to the beam to column intersection point or by the separation of brace connections near the midspan of the beam. This chapter discusses a design procedure for EBF with flexurally dominated links. The usual requirement to restrict inelastic action to the links may be relaxed. The effect of this will be to avoid the necessity for the reinforcement of the beams. The design procedure then ensures that, for a selected earthquake, the principal design criteria are satisfied. Thus, inelastic action is confined to the beams. The response of an eight-story structure to other earthquakes is examined. Severe damage is restricted in all cases to the link in the roof level beam. Suggestions are made to overcome this problem.