EXPERIMENTAL AND NUMERICAL INVESTIGATIONS ON HISTORICAL MASONRY WALL SPECIMENS TESTED IN SHEAR-COMPRESSION CONFIGURATION

The paper presents the experimental investigation carried out on wall specimens reproducing the ancient masonry of several monumental building located in the old city centre of L'Aquila (Italy) and damaged by the April 2009 earthquake. The wall specimens were prepared in accordance with the traditional technique, using original stone elements and typical poor mortar. Subsequently, the specimens were consolidated with mortar injections. Other specimens were also reinforced with Ultra High Tensile Strength Steel wires applied as coating technique (not wrapped). Shear-compression tests were carried out on the wall specimens to evaluate the effects of the reinforcements both in terms of final stiffness and strength of the specimens. A non-linear Finite Element Model (FEM) was developed to reproduce the experimental tests and to better understand the damage phenomena. The load-displacement curves predicted by the FEM compared quite well with the experimental ones. The failure mode of the specimens was properly captured by the FEM. The effectiveness of the external reinforcement was proved to strictly depend on the coating adhesiveness to the walls surface. The premature debonding of the external reinforcement was demonstrated to cause the fragile post-peak behaviour during both the actual experimental test and the numerical simulations

Comparing test methods for the mechanical characterization of fiber reinforced concrete

Different tests are proposed by international standards for the evaluation of the mechanical properties of fiber reinforced concrete (FRC); among them, either beams or round determinate panels are generally used. However, different tests are accepted by design codes if reliable correlation factors between standard parameters are provided (fib Model Code 2010). Within this context, a broad experimental program on both beams and round determinate panels was carried out in order to provide a critical discussion on material characterization and to evaluate possible correlation factors. Beam tests according to European (EN 14651), American (ASTM 1609), and Japanese (JCI-SF4) standard, as well as small round panels and large round panels (according to ASTM 1550) were studied within an experimental program comprising 189 beams and 90 round panels. Unlike previous researches, mainly focused on steel fibers, two types of macro-synthetic fibers were considered. Based on these experimental results, a comparison between test methods is presented, along with correlation approaches are proposed and critically discussed