A four-phase program to improve the specific energy absorbed by axially crushed composite collapsible tubular energy absorber devices was undertaken. In the first phase, examining of the crushing behaviour of non-triggered tubes was carried out. The second phase is aimed at obtaining the best position for the triggered wall. The third phase focuses on the effects of material sizing in order to understand the influence of triggered wall length on the responses of composite circular tubes to the axial crushing load. The results of these three phases of the study contribute to the fourth whose objective is to optimize the shape geometry of the crosssection area to further improving in tube energy absorption capability. The experimental results demonstrated the strong potential benefits of optimizing the material distribution. The sizing and shape optimization of composite collapsible tubes exhibited a pronounced effect on their capability to absorb high specific energy under axial compressive load.

To increase the capacity load carrying of the beams, post tensioned metal straps are fully wrapped around the beams in their tensile zone in this study. In total four normal R.C beams with the depth of 160 mm, height of 240 mm and total length of 2100 mm are cast and tested under four-point load testing. The number of variables is kept to minimum of two which are the number and location of the straps. It is found that using post tensioned metal straps fully wrapped around the beams can increase the load-carrying capacity of the beams by 36% at least and 39% at a max. The main factor in influencing the rate is the location of the straps. A complete guide on using the material along with its application on the beams are explicitly described in the paper.