Julio Garzón-Roca

Prediction of the shear strength of reinforced masonry walls using a large experimental database and artificial neural networks

Abstract This paper analyses the accuracy of a selection of expressions currently available to estimate the in-plane shear strength of reinforced masonry (RM) walls, including those presented in some international masonry codes. For this purpose, predictions of such expressions are compared with a set of experimental results reported in the literature. The experimental database includes specimens built with ceramic bricks and concrete blocks tested in partially and fully grouted conditions, which typically present a shear failure mode. Based on the experimental data collected and using artificial neural networks (ANN), this paper presents alternative expressions to the different existing methods to predict the in-plane shear strength of RM walls. The wall aspect ratio, the axial pre-compression level on the wall, the compressive strength of masonry, as well as the amount and spacing of vertical and horizontal reinforcement throughout the wall are taken into consideration as the input parameters for the proposed expressions. The results obtained show that ANN-based proposals give good predictions and in general fit the experimental results better than other calculation methods.

Increasing flexural performance of hybrid sandwich panels by using strain hardening cementitious base composite and glass fiber-reinforced polymer:

The present paper explores different techniques for increasing flexural performance of composite sandwich panels made of hand-layup glass fiber reinforced polymer skins and low density closed cell polyurethane foam core. An experimental program compares the performance of simple panels face to the use of transversal and longitudinal internal glass fiber reinforced polymer ribs and the installation of a strain hardening cementitious base composite top layer over the panels. Based on the experimental results, finite element models are also developed to simulate the flexural behavior of tested panels and conducted an in depth analysis of the techniques studied. Obtained experimental and numerical results show that the use of internal glass fiber reinforced polymer ribs (especially in longitudinal direction) along with the use of strain hardening cementitious base composite significantly and effectively increases the flexural performance of sandwich panels. The high stiffness to weight ratio capacity of the panels attained by applying the proposed method enables its use in rehabilitation of historical places. Furthermore, the proposed techniques could be helpful for strengthening available composite sandwich panels.

Composite modular floor prototype for emergency housing applications: Experimental and analytical approach

The present paper explores a new modular floor prototype to be used in emergency houses. The prototype is composed of a frame structure made of glass-fibre-reinforced polymer tubular pultruded profiles, a slab made of sandwich panels with a polyurethane foam core and glass-fibre-reinforced polymer skins, and a tailored connection system that provides integrity between assembled components. A series of experimental tests are carried out including flexural tests on a single panel, on two and three connected panels, and on the assembled floor prototype. The behaviour of the panels is analysed when they are not considered part of the glass-fibre-reinforced polymer framed structure, namely the failure mechanisms and the efficiency of the proposed connection system between the panels. The performance of the floor prototype to support typical load conditions of residential houses is also assessed. Additionally, an analytical model was used to deeper study the behaviour of the developed sandwich panels, connection system and the modular floor prototype.

Estimation of Cerchar abrasivity index of andesitic rocks in Ecuador from chemical compounds and petrographical properties using regression analyses

An important issue in any rock engineering project is the adequate prediction of tool consumption. Excavation tools are subjected to wear, and repair/replacement of those tools is usually an important expense on any excavation budget. The key factor that affects wear of excavation tools is rock abrasivity. In mining and civil engineering, rock abrasivity is typically measured by the Cerchar abrasivity index (CAI), which is obtained in laboratory from a Cerchar abrasivity test. This paper studied the relation between CAI and the chemical compounds and petrographical properties of andesitic rocks from the central area of Ecuador. A series of regression analyses are performed to study the influence of the different chemical compounds and petrographical properties on the CAI value. Results show that it is possible to make a good estimation of CAI from the plagioclase grain size and/or the content of SiO2, FeO, MgO, CaO, Na2O and K2O compounds.