Isabel Valente

Experimental analysis of Perfobond shear connection between steel and lightweight concrete

This paper describes the experimental tests carried out at the University of Minho using Perfobond connectors and lightweight concrete. The main objective of these tests is to describe the connection behaviour and to analyse and compare the contribution of the different elements to the slip measured between the steel profile and the concrete slab. In this way, it is possible to define the connection ductility. The test configuration follows some of the EC4 recommendations and repeats some dispositions referred to by Oguejiofor and Ferreira. The parameters under study are the concrete strength, the reinforcement disposition and the Perfobond rib existence and spacing of holes. An important comparison with the experimental results achieved by different authors using normal weight concrete may then be established.

Axial performance of jointed sandwich wall panels

AbstractThroughout this paper, a new system for connecting composite sandwich wall panels is proposed. The relevant structural components are investigated with the aim of utilizing these panels as ...

Mechanical characterization of ancient Portuguese riveted bridges steels

In repairing and retrofitting processes of ancient riveted steel bridges is crucial to assess the structural state of old metals to guaranty structural safety. Metals under long-time operations (mild, rimmed low carbon steels <0.1% C, puddle irons) and cyclic loading present a tendency for degradation processes. The case-studies of this work are five metallic bridges existing in Portugal (Luiz I, Eiffel, Fao, Pinhao and Trezoi). This work presents the study of some characteristics of materials extracted from the five case-studies, such as: monotonic tensile strength, chemical composition, microstructures, hardness, notch toughness and fatigue crack propagation. In terms of monotonic tensile tests, the materials from Luiz I, Eiffel and Fao bridges are similar to puddle steel and the materials from Pinhao and Trezoi bridges are similar to mild steel. In terms of toughness only the material from the Pinhao bridge exhibits acceptable toughness properties, considering current design requirements. The materials from the other bridges exhibit relatively low toughness properties. The fatigue crack propagation data from the old Portuguese riveted steel bridges were correlated using the Paris’s law and the possibility for a design crack growth rate was discussed.

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.

Structural performance of hybrid sandwich slabs under shear loading

In a hybrid panel with glass fiber-reinforced polymer (GFRP) bottom skin and ribs, and deflection hardening cementitious composites (DHCC) top layer, it is very important to provide good shear connection between these various components in order to increase the load carrying capacity of the resulting hybrid slabs and a larger increment of deflection before the occurrence of the structural softening of this panel. The effectiveness of the proposed hybrid sandwich panels strongly depends on the performance of the shear connectors. The efficiency of indented shear connectors in improving the flexural performance of hybrid sandwich panels is here demonstrated. Since the efficiency of indented shear connectors in the hybrid sandwich panels is unknown, efforts are made in this paper in investigating the shear performance of hybrid slabs. A special focus is given on the indented shear connector’s behavior, considering different shear span ratios in ranges of 2.00, 1.39, and 0.77. In this regard, six hybrid sandwich panels were manufactured and experimentally tested under different shear loads. Then, the results are interpreted comprehensively. The results obtained show that the GFRP rib thickness and height, and shear span ratios influence the damage events and the structural performance of the hybrid sandwich panels. Moreover, it was observed that using indented shear connectors in the hybrid slabs, regardless of the shear span ratios, provides high load capacity, high stiffness, and large residual deflection.

Structural Assessment of Companhia Aurífícia, a 19th Century Industrial Building Located in Northern Portugal

ABSTRACT Companhia Aurifícia is located in Porto, Portugal, and was founded in 1864. It was a pioneer factory in the industrial production, casting, rolling, and stamping of metallic objects and laboured for about 150 years, in areas as jewelry, manufacture of parts in silver and gold or the production, and casting of various metals. In 1866, it began laboring in Rua dos Bragas, its present location, and in 2003 ceased all activities.Companhia Aurifícia is an industrial complex including several buildings, all located in the same block. It is a precious example of the industrial architecture in Porto, where the still existent retaining walls, structures, machinery, and decorative elements make it one of the last examples of 19th century industrial life of the city.This article aims to evaluate the safety condition of one of the buildings included in this industrial complex, in order to propose the necessary strengthening interventions.

Non-Destructive Tests for the Structural Assessment of a Historical Bridge over the Tua River

Paradela Bridge is a metallic bridge located along the bank of the Tua River in northern Portugal. While the bridge is not currently in service, its structure is representative of many metallic truss structures built across the continent between the XIX and the XX century. Tua Line belongs to the Douro area that UNESCO recently declared as world heritage. This study acquires its importance since it might serve as an insight for the study of many other similar structures all over the country. This paper comprises a historic investigation of archived documents, an on-site survey to evaluate its present conditions, a dynamic testing and the construction and calibration of numerical models in finite element analysis (FEA) software, structural assessment and capacity rating estimation. The purpose of constructing numerical models was to evaluate the suitability of the bridge under the original loading and in accordance to modern design standards. The historical research revealed that the truss bridge was designed as a simply supported element and that a series of hand calculations were carried out on individual structural elements (e.g. main trusses, stringers and floor beams). Furthermore, a dynamic test was conducted in order to identify the global dynamic properties of the structure and to calibrate numerical models that ensure reliability and representativeness. FE models served through the structural assessment of the bridge in accordance with modern design codes and to estimate the safety of the bridge. Likewise, a nonlinear failure analysis was also conducted in order to estimate the capacity rate of the bridge and the likely failure modes.

A probabilistic assessment methodology for life cycle analysis of structures

The life cycle analysis (LCA) of structures is a framework that evaluates its condition and safety within the whole life through specific performance indicators. Management decisions are then taken considering this state and in a way that cost is optimized. Used indicators are strictly correlated and they are usually determined through a structural assessment procedure. However, this procedure is carried of different sources of uncertainty. This paper presents one methodology for a probabilistic assessment which considers and mitigates some of these uncertainties. This algorithm is based in both optimization and Bayesian inference techniques. It will be applied with two structures, respectively, a reinforced concrete and one composite beam. Two performance indicators will be computed considering traditional probabilistic assessment techniques and this methodology Obtained results pointed out the economic advantages of considering this methodology.

Non linear probabilistic analysis of reinforced concrete structures

The behaviour of reinforced concrete bridges is doted of uncertainty as main parameters, like the ones related to material properties, are variable and not deterministic. In order to take this into consideration, a non linear probabilistic analysis should be developed. This paper presents an application of it on the evaluation of the structural behaviour of two batches of reinforced concrete beams, which were loaded, in laboratory, up to failure. However, when performing it, a previous attention must be paid to the intervenient parameters. In fact, on the one hand it is important to consider the highest number of parameters as possible but, on the other hand, this implies higher computational costs. In order to avoid this, it is essential to identify, by developing a sensitivity analysis, all critical parameters. A comparison of numerical results with obtained experimental data is executed, being, the advantages of such kind of analysis, pointed out.