Pedro Pacheco

Technical Challenges of Large Movable Scaffolding Systems

Abstract The method of construction of decks of bridges and viaducts with several spans using movable scaffolding systems (MSS) is very efficient and competitive. This solution is generally used for the 40 to 60 m span range. Over the last few years, new experiences have been acquired and new solutions have been developed for the 70 to 90 m range (large MSS or LMSS). In this range, unexpected economical results may be achieved if the number of spans is high and/or if the costs of piers and foundations are relatively high. With LMSS it is possible to achieve very high productivity ratios. The application of LMSS implies significant technical challenges. Some are similar to the more common MSS, but others become more relevant. This paper discusses bridge–equipment interaction including main vertical loads on the bridge, horizontal forces on piers, wind actions, wind-induced vibrations on piers with MSS stabilization, accidental MSS-induced actions, thermally induced horizontal displacements, and deflection control. Two real examples are presented. The design criteria recommendations are listed in the conclusion section.

A Scaffolding System strengthened with Organic Prestressing - the first of a new Generation of Structures

The first full scale application of a movable scaffolding system strengthened with an organic prestressing system (OPS) is briefly described. The main characteristics of the steel structure and of the OPS technology are presented and significant aspects of the equipment’s structural behaviour are given. The advantages of this innovative solution are established. Results prove that this control system enables the design of lighter scaffolding systems, reducing their service deflection at the same time.

Experimental study of a launching gantry reduced scale model strengthened with organic prestressing

An experimental study of a launching gantry reduced scale model strengthened with organic prestressing (OPS) is briefly described. Results prove that this control system provides a significant increase in the load capacity of gantries, reducing at the same time their service deflection. Technical feasibility of the system is also confirmed. Full scale critical issues are identified and measures to minimize their importance are presented.

New Modular Bridges Solutions—A sustainable Solution to Connect People

The present paper describes a new modular bridge solution with higher range of spans, load capacity, fast assembly and smart packing. As an upgrade of the conventional Bailey bridges type, BERD developed a new structural solution designed to be launched by increment launching with a superfast telescopic system. In remote locations where building a conventional concrete bridge can represent a logistic challenge regarding materials and equipment transport, the modular steel bridges aim to minimize the logistic operations impact of the infrastructure. In fact, modular bridges are aligned with the three main principles of sustainability in construction—reuse, reduce and recycle. Being reused several times with minimum maintenance needed, high capacity to be adapted to several span lengths and totally recycled in the end of life cycle, modular bridges highly fits in the sustainability concept. Also the new range of spans up to 120 m offered by BERD, opens new possibilities of bridging margins reducing distances between populations and also social and economic impact. Prepared to be easily assembled and launched in few days (less than one week), the modular bridges main applications are: new bridging, civil protection, infrastructures repairs and military support.

Fatigue Design and Prevention in Movable Scaffolding Systems

Abstract The Movable Scaffolding System (MSS) is a heavy construction equipment used for casting situ of concrete bridge decks. In the past decades, MSSs have become increasingly complex and industrialized, enlarging its span ranges, incorporating auxiliary elevation machinery and increasing productivity. The tendency nowadays is for strong reutilization and the notion of MSS as a disposable or temporary structure is somehow reductive. The main structure of MSSs may be potentially exposed to fatigue, usually characterized by low number of cycles with significant stress amplitude. Fatigue may be prevented through adequate design; judicious selection of materials; demanding quality control and implementation of robust inspection and maintenance plans.

A new concept of overhead movable scaffolding system for bridge construction

In the last decade, a research and development process, initiated in the Faculty of Engineering of the University of Porto has brought out an innovative technology for bridge construction: Organic Prestressing. This new technology is now being applied to a brand new generation of movable scaffolding systems. The present paper presents a new concept of overhead movable scaffolding systems for in situ bridge construction, in which the scaffolding structure is similar to a “bowstring”, with the particularity of having an arched upper chord and an actively controlled lower chord.