Full Description

This paper reports the results of a series of experiments performed on welded connections between steel tubes. The exploration, the second in a four-phase program being conducted at the University of Texas, was directed toward determining the distribution and magnitudes of local stresses occurring in such joints when the joined members are subjected to axial loadings. Impetus for the research was provided by the petroleum industry which utilizes tubular members in many structures especially offshore drilling towers and platforms.

Ten specimens representative of welded joints used in practice were tested. Seven of the specimens involved a single brace (small tube) framing onto the unbroken surface of a chord (larger tube). In four of these, the axis of the brace made a 90 angle with the axis of the chord and three had brace angles of 45. The remaining three specimens were joints with multiple (3) braces joining to the surface of the chord. The axes of the three braces in each of these specimens met at a single point on the axes of the chord. Further, the four axes lay in a single plane with the brace axes making angles of 45, 90, and 135 with the single chord axis.

With the ends of the chord securely fastened into a loading jig, a variety of axial loads were applied to the braces. The stresses at critical points in the joint were monitored from electrical resistance strain gages located on the surfaces of the tubes. The measured stresses provided the information required to construct the contours of isostatics and isobars, the stress patterns, and the stress distributions that are included in the appendix for each of the loadings on each specimen tested.

These results were then used to isolate the location and magnitudes of the significant stresses in each specimen. Because the dimensional parameters for the T-joints were systematically varied from specimen to specimen, their individual influence on the stresses could be quantitatively appraised. This was done in the form of design nomographs. These charts should provide invaluable information to those responsible for the structural integrity of such joints in service.

The joints were also tested to failure and qualitative comments concerning their behavior at and near ultimate are included for completeness

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Published: 1967 Number of Pages: 36 File Size: 1 file , 1.5 MB