Enhancing the Structural Performance of Masonry Structures by Post-Tensioning

Abstract

Despite the evident advantages of combining masonry with prestress, their joint use has been poorly exploited during the last decades. This paper claims the high potential of masonry as a primary load-bearing material when combined with post-tensioning. This work deals with arch footbridges and antifunicular structures. With respect to the first, this research illustrates the introduction of external loads by internal post-tensioning to favourably increase the axial forces in a masonry arch, and consequently improving its structural behaviour. With respect to the second, this work shows how bending moments in a non-funicular 2D curved geometry can be eliminated through an external post-tensioning system. In summary, this research strongly expands the range of post-tensioned masonry structures that exhibit a bending-free (or quasi bending-free) behaviour and, de facto, opens up new possibilities for designs that combine structural efficient solutions with traditional materials.

Re:Crete – reuse of concrete elements in new structures: A footbridge prototype

“…Due to the arch slenderness and the flat geometry, the thrust line lies outside the cross-section (Figure 2(a), pink area). Post-tensioning the arch via centric cables creates an artificial normal force and radial load, which over-compresses the RC blocks so that the thrust line is brought back inside the cross-section, as shown in Figure 2(b) (Todisco et al 2018). Via the post-tensioning, the slender segmental arch becomes stable also for asymmetric loading and without any backfill, while experiencing stresses far below the compressive strength of regular building construction concrete.…”

Re:crete – a Footbridge Made of Reused Concrete Blocks

“…The points of application of all such resultants along the arch is the thrust line, illustrated in pink on Figure 3. When the thrust line is beyond the cross-section, the arch becomes unstable [23,24]. As detailed in Figure 3(a), without post-tensioning, the thrust line of the Re:Crete arch would be outside the cross-section under asymmetrical loads.…”