No abstract

Bending moments due to permanent loads can be strongly reduced in a generally shaped structure by introducing a set of additional forces through an external posttensioning system. The response of these structures under live loads has not been studied yet; therefore, this work investigates the behavior of these structural systems under load distributions that differ from the permanent ones. First, a definition of a moment‐based efficiency is proposed. Next, a parametric analysis is carried out to evaluate the performance of these structural systems by varying the two main design variables and other relevant parameters (strut connection and orientation, discretization, efficiency definition, etc.). Finally, the methodology is applied to a case of study where several posttensioned alternatives are compared to the standard one (i.e., without posttensioning) to prove the benefits of adopting external posttensioning in terms of material‐saving.

<p>The El Salvador Project is a student-led initiative born in 2001 at Imperial College London that provides simple and effective engineering solutions to rural communities in El Salvador. The projects are developed in close collaboration with the Salvadorian NGO REDES and the UK-based charity Engage for Development. This paper presents the work developed over the summer 2019, when a footbridge was constructed for the School of the community of El Yomo, in the town of Alegría. The footbridge was intended to restore the path connecting the main settlement with the local school, which heavy rainfall had eroded in the previous years forming an impassable ravine. The footbridge was designed as a 15 m long steel truss beam supported on masonry walls. The construction was a collective effort. The main challenges faced during construction were the unexpected conditions of the site, the unreliable supply of materials and the lack of means for excavation, lifting and auxiliary constructions. The success of the project relied considerably on the knowledge of the local workers. The involvement of the community helped develop a feeling of ownership over the project which has resulted in a strong commitment in its maintenance since the opening. The footbridge was enthusiastically inaugurated by the community and has provided the children of El Yomo with a safer and faster route to their school, based on a comprehensive risk management approach.</p>