The capacity and behaviour of cold-formed steel built-up sections are affected by the arrangement of the connections. This study aims to determine the effect of the screw spacing to the bending capacity and behaviour of the cold-formed steel built-up box section which made from lipped-channel (1.0 mm thick, 81 mm web height, 8.5 mm lip height, upper and lower wing width 38 mm and 40 mm). A total of 19 beams with a length of 1200 mm each are subjected to pure bending moments by applying two point loads spaced 600 mm in the midspan. The screw spacing variations in the moment span are 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 328 mm, and 350 mm. The test results show the average of bending capacity of the beam test is increasing with the reduction in screw spacing while the screw configuration also affects the beam capacity. Analysis of the bending capacity using the effective width method and the direct strength method based on AISI S100-16 gives very conservative results. The failure mode of the built-up box sections were observed in the form of local buckling, distortion, and lateral-torsional buckling.

This paper summarizes new application of CFS in bridge constructions where a seven meters long pedestrian bridge was constructed. The bridge has 1.2m width, 0.8m depth, and is composed of CFS Warren truss and bondek floor systems. Natural frequency of the bridge considering only dead load application was found as 8.54 Hz and decreased to 7.08 Hz when the live load was included. Under static load test, the application of dead load only and both dead and live loads yielded a maximum deflection of 3.53 and 8.1 mm, respectively. Normal walking and running pedestrian loads were carried out created a maximum acceleration equaled to 0.11g. Lastly, sinusoidal waves application facilitated through a three-phase induction motor having self-weight of 24.86 kgf at frequency equal to 8.5 Hz was performed for one hour resulting no decrease of the natural frequency, thus the bridge can be assumed to experience no noticeable stiffness degradation.