Girder End Research Articles

Release Methodology of Strands to Reduce End Cracking in Pretensioned Concrete Girders

Results of numerical and experimental investigations concerning the causes of prestressed concrete girder end cracks are reported in this paper. The cracks, which developed during the flame-cutting release process, resulted from the restraining effect of unreleased strands as the girders shortened from the partially transferred prestress and from shear stresses generated by the cutting order of the strands. Several methods were examined to eliminate the cracks, including changes to the strand cutting pattern, debonding some of the strands in the end regions, and increasing the slope of the top surface of the bottom flange. The first two of these methods were implemented in the field and found to be successful.

コンクリート充填型鉄骨造U型ブラケットの応力伝達機構

This paper presents a new method of adjoining .the ends of steel girders and proposes design equations based on an assumption. According to a new method, a steel girder can be connected to a U-shaped bracket without any welding or high-tension bolts. This is made possible by filling concrete between the steel girder's end and inside of the U-shaped bracket. Sixteen steel girder joint specimens were tested in order to verify the assumption that tensile stress of steel girder is transferred to the bracket through the compressive strut of the concrete. Test results explain the stress transfer mechanism.

Experimental test on the Transverse Strength of a Large Bulk Carrier

This paper presents the results of experimental test on the transverse strength of 120, 000 DWT, class bulk carrier built by MHI in September 1970.The test was carried out under light loaded afloat condition by filling sea water into the cargo hold/water ballast tank, and the measurements were made on the stresses of double bottom structure, hopper tank, topside tank and side frames as well as the deformation of the hold.On the other hand, theoretical analysis was made by using a 3-dimensional frame structure model. Furthermore, in order to examine more accurately the stress distribution of the members in hopper tank and topside tank, calculation was carried out by finite element method.The general conclusions obtained from this investigation are as follows : (1) In general, theoretical predictions show a fairly good agreement with the experimental results. Accordingly, it is concluded that the reasonable estimation on the transverse strength of bulk carriers can be made by this analytical method of 3-dimensional frame structure model.(2) Comparatively high stress consentrations were observed at the ends of longitudinal girders and floors.(3) Hopper tank is very effective for the strength of double bottom structure in this test condition. Boundary condition of the double bottom seems near to fixed one.(4) Almost of the shear force in floor plate flows into the sloping transverse member of hopper tank.(5) The degree of the end fixity of the hold frames connected to balancing brackets is about seventy-five percent of those connected to transverse rings.

Effect of elasto-plastic shear springs on increasing the seismic safety of a half-through type reinforced arch bridge

This paper presents the results of nonlinear time history response analysis for a half-through type reinforced concrete arch bridge using three-dimensional analytical model. Eight different analytical models with elasto-plastic shear springs in longitudinal, transverse or vertical direction between lower cross beam and main girder, or between end of main girder and abutment are analyzed to investigate the efficient location of shear springs. Numerical results clarify that the model with shear springs in both longitudinal and transverse direction at end of girder is most effective to increase the seismic safety.

Moment-Rotation Characteristics of Shear Connections

In simple type construction it is assumed that the ends of beams and girders are connected for shear only and are free to rotate under load in the plane of loading. A standard connection used has been a pair of angles fastened to the web by welds and field bolted or welded to the supporting girder or column as shown in Fig. 1. This type of connection, even when designed for shear only, has proved most reliable and among its advantages are: 1. The longitudinal position of the angles can be adjusted slightly to allow for over- or under-cut in the length of the beam. 2. The projection of the angles beyond the end of the beam provide some clearance for erection.

Anchorages for Large Tainter Gates

Novel type anchorages whose distinguishing features and economy derive from single tie girder placed centrally within spillway pier, single anchor at upstream end of girder, and its downstream end in concentric grouping with inclined side arms of adjacent tainter gates.

Anchorages for Large Tainter Gates

Novel type anchorages whose distinguishing features and economy derive from single tie girder placed centrally within spillway pier, single anchor at upstream end of girder, and its downstream end in concentric grouping with inclined side arms of adjacent tainter gates.

THE RELATIVE RIGIDITY OF WELDED AND RIVETED CONNECTIONS

Little quantitative information being hitherto available concerning the degree of restraint developed at the ends of steel beams and girders with welded connections, and the extent of possible related economies and improvements in frame stiffness being correspondingly uncertain, the experimental investigation of two distinct aspects of joint rigidity was undertaken. These were:(a) The relative capacity under gravity load of beam-girder and beam-column connections for developing beam restraint, or continuity, designed with a view to reducing the required weight of the connected beam.(b) The relative values of certain typical connections in resisting the deformation of a frame due to lateral loads, either in one direction or subject to reversal.Two series of specimens were fabricated and tested in relation to plain rating beams. The first series, designed for the purpose of studying beam continuity, consisted of ten 9-in., 20.5-lb. Bethlehem beam double-cantilever specimens, employing five different types o...

IV. On the practical solution of the most general problems in continuous beams

1. It is not necessary to enter into the question of the advisability of employing continuous girders in bridges with spans of less than 200 feet, but it is generally conceded that the increased economy due to the employment of continuous girders in longer spans more than counterbalances the well-known practical objections to continuity. Hence the practical solution of the general problem—given the conditions at the ends of a continuous girder, the spans, the moment of inertia of all cross sections, and the loading, to find the bending moment and shearing stress in every cross-section, is not unworthy of our attention.