The last decade saw the emergence of a new type of space truss built with continuous chord members. Earlier studies on these trusses confirmed that besides the cost savings resulting from their simple jointing methods, their behaviour is sound and ductile. The present study investigates the possibility of using either a concrete slab or top timber boards acting compositely with the top chord, to improve the behaviour of these trusses. New techniques are developed to allow the easy and inexpensive attachment of both types of top continuum. With these techniques, a high level of shear interaction can be developed, leading to significant improvements in behaviour. The paper also introduces an analytical study based on the finite element method for the analysis of space trusses with continuous chords, both in the composite and non-composite states.
Externally post-tensioned tendons can cause an initial compressive stress in steel-concrete composite sections at the hogging moment region, and then a part of the tensile stress in the concrete flange can be relieved. This study presents a detailed finite element analysis of the nonlinear flexural response of continuous steel-concrete composite beams strengthened with externally post-tensioned tendons. The initial post-tensioning force is introduced as an initial strain in the truss element that used to simulate the external tendons. The accuracy of the finite element model is validated using existing experimental works. The effects of tendon eccentricity, longitudinal steel rebar ratio, and initial post-tensioning force on the beam behavior are explored. Furthermore, deterministic and stochastic shrinkage effects are carried out to obtain the long-term random responses of the strengthened beams as well as unstrengthened beams. However, the ultimate capacity of the strengthened beam increases only by 8%, the cracked moment redoubles, and an affirmative behavior over the unstrengthened beams is obtained. Also, a rapid decay in the long-term deformation of continuous steelconcrete composite beams is obtained at the early age while a linear decrease in the remaining part of the age occurs.
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