ABSTRACT

This paper reports the results of three static tests on tubular multi-planar KTKT-joints. The relevant geometry parameters investigated are: the diameter ratio ß, the chord thinness ratio y, and the out-of- plane angle ф. The aim of the tests is to investigate the static behavior of the joints and to propose an ultimate capacity equation. From the test observations, it was found that failure of the specimens was due to plastification of the chord wall under the compressive braces. The behavior shows that compressive loads redistributed from the diagonal braces to the vertical braces after failure of the diagonal compressive braces. The interaction between the diagonal and vertical compressive braces is used to propose the ultimate capacity equation.

INTRODUCTION

Multi-planar CHS KTKT-joims shown in Figure 1 are joints in statically indeterminate trusses. KTKTjoints are usually applied to roof truss structures, tower structures as well as offshore jackets. No tests regarding KTKT-joints are known and hence, no design guidance is available. However, multi-planar KK-joints were tested by Makino et al. (1984), Paul et al.(1993) and Yonemum et al.(1996) and were studied numerically by Lee and Wilmshurst (1996, 1997), v, hile uni-planar KTjoint tests were carried out by Wilmshurst et al.(1998). In the light of those studies, this paper discusses the ultimate behavior of KTKT-joints under static load. This paper first describes the tests on three KTKT specimens, reports the ultimate behavior of KTKT-joints and furnish a basis for the ultimate capacity equation for KTKT-joints.

SPECIMENS AND GEOMETRY

Three specimens were tested to investigate the ultimate behavior of KTKT-joints. The configuration, nomenclature and brace designation of the three specimens are shown in Figure 2. The measured dimensions of the three specimens are given in Table 1. The member sizes of the specimens provide two variations in ß, γ, and ф.

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