Paulo J. S. Cruz

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.

Performance of Vibration‐Based Damage Detection Methods in Bridges

The important advances achieved in modal identification, sensors, and structural monitoring of bridges have motivated the bridge engineering community to develop damage detection methods based on vibration monitoring. Some of these methods have already been demonstrated under certain conditions in bridges with deliberate damage. However, performance of these methods for damage detection in bridges has not been fully proven and more research must be done in this area. In this paper, 6 damage detection methods based on vibration monitoring are evaluated with 2 case studies. First, the dynamic simulation and modal parameters of a cracked composite bridge are obtained. Here, the damage detection methods are evaluated under different crack depth, extension of the damage, and noise level. Second, damage is identified in a reinforced concrete bridge. This bridge was deliberately damaged in 2 phases. In this example, damage detection methods, which do not require comparison between different structural conditions, were applied. In the first case study, evaluated damage detection methods could detect damage for all the damage scenarios; however, their performance was notably affected when noise was introduced to the vibration parameters. In the second case study, the evaluated methods could successfully localize the damage induced to the bridge.

Experimental behaviour of end-plate beam-to-column composite joints under monotonical loading

An experimental research program on end-plate beam-to-column composite joints under monotonical loading is presented. The major focus relates to the identification of the contribution of the concrete confinement in composite columns to the behaviour of the joint, coupled with a thorough assessment of the various loading possibilities, ranging from symmetric and anti-symmetric loading on internal nodes to external nodes under hogging and sagging moments, typical in seismic regions. Comparison with current methodologies in the analysis of composite joints is also presented.

Scavengers for achieving zero formaldehyde emission of wood-based panels

This work examines the performance of three formaldehyde scavengers in wood-based panels. Sodium metabisulfite, ammonium bisulfite and urea were applied in different physical forms during particleboard production, and the resulting physico-mechanical properties (internal bond strength, thickness swelling, density and moisture content) and formaldehyde emission levels were compared. Formaldehyde content was measured using the perforator method, and formaldehyde emission was evaluated both by desiccator and gas analysis methods. The chemical reactions involved in each formaldehyde scavenging process are proposed and discussed. The tested scavengers showed distinct performances under the different emission testing conditions, which were interpreted in terms of the stability of the chemical compounds formed upon formaldehyde capture. Sodium metabisulfite proved to be an excellent scavenger for all formaldehyde methods allowing the production of particleboard panels with zero formaldehyde emission.

Database for the semi-rigid behaviour of beam-to-column connections in seismic regions

The behaviour of steelwork connections has long been recognised as complex. A database of test results for connection behaviour constitutes an essential step towards the development of design methodologies, allowing more researchers to investigate in this field without the financial burden of carrying out experimental work, avoiding being misled by incomplete or incorrect data, and opening the way to design assisted by testing. A database of experimental results for steel and steel-concrete composite connections is presented which encompasses graphical treatment of data, numerical manipulation and statistical treatment of groups of results, allowing easy comparison of connection behaviour. Simplified constitutive models for the hysteretic behaviour of connections are presented and included in the database for comparison and calibration with experimental results. The database SERIWWW was developed according to the following specifications: Possibility to introduce test results for any type of connection in free form format, irrespective of the type of connection (existent or not); Possibility to deal with any material; Possibility to deal with dynamical tests; Possibility to deal with numerical simulations; Easy interchange (import-export) with any commercial program (EXCEL, ACCESS, etc.); INTERNET on-line implementation. and implemented as independent modules which correspond to different levels of utilisation, as shown in Table 1. An experimental project of beam-to-column composite connection cyclic and dynamic tests currently under execution is presented where both con

Probabilistic models for mechanical properties of concrete, reinforcing steel and pre-stressing steel

This paper presents probabilistic models for mechanical properties of pre-cast and cast-on-site concrete as well as of reinforcing and pre-stressing steel. An extended review of models available in the literature is made and new probabilistic models are developed based on a significant amount of data collected by the authors. New probabilistic models are proposed for concrete ultimate strength (separately for precast and cast-in-place concretes), for yield and ultimate strength of reinforcing steel and for proportionality limit and ultimate strength of pre-stressing steel. The new models account for a recent improvement of production and are more appropriate for the probabilistic assessment of modern concrete structures then the models available in the literature.

Guidance for European Structural Design of Glass Components

Keywords: structural glass Reference EPFL-REPORT-196634 Record created on 2014-02-13, modified on 2016-08-09

Application of radar techniques to the verification of design plans and the detection of defects in concrete bridges

Non-destructive tests (NDT) are an essential tool used in special inspections to gather detailed information about the condition of a bridge. The inspection of bridge decks is a critical task, and, currently, can be successfully carried out using a wide range of NDT techniques. Nevertheless, some of these techniques are excessively expensive and time consuming. One of these techniques, the ground penetrating radar (GPR), has been used for some decades in the non-destructive inspection and diagnosis of concrete bridges. GPR is useful to find general information about the true position of reinforcement and tendon ducts, and check the quality of the construction and materials. A significant number of reinforced and prestressed concrete bridges are deteriorating at a rapid rate and need to be repaired and strengthened. During these rehabilitation processes, designers are often faced with a lack of original design plans and unawareness of the real position of reinforcement and tendon ducts. In this paper, three case studies of the use of GPR techniques for the inspection of concrete bridges are presented and analysed. The main aim of this research is to show the strong need and usefulness of these techniques, which can provide non-visible information about structural geometry and integrity required for strengthening and rehabilitation purposes.

Practical implications of GPR investigation using 3D data reconstruction and transmission tomography

Non-destructive investigation using ground penetrating radar is becoming more popular in the inspection of civil structures. Currently, traditional 2D imaging is used as a preliminary tool to find possible areas of interest for more detailed inspection, which can be accomplished by more advanced techniques like 3D image reconstruction or tomography. In this paper, a general overview of the work done at University of Minho regarding these techniques is presented, together with their limitations and advantages over typical radargrams, with implications for civil engineering applications. For this purpose, data acquisition on two large masonry walls and one large concrete specimen have been carried out, using reflection mode, 3D reconstruction and transmission tomography. The specimens have been specially built for non-destructive inspection techniques testing, incorporating different materials and internal voids. Radar tomography and 3D image reconstruction techniques provided much more detailed information about structural integrity and shapes and location of the voids, when compared to 2D imaging originally used for potential target identification.

Load capacity of damaged RC slab spans of railway-bridges

European railway bridges are relatively old and degradation processes cause defects diminishing their load capacity. This paper presents computer-based DAGA system supporting the load capacity assessment of damaged railway slab spans made of reinforced concrete (RC). Construction of the analysed bridge spans and types of considered defects (mainly material losses and strength reduction) are based on a study of the railway infrastructure in Poland and Portugal as well as on results of the international research projects focused on railway bridges. Presented system is equipped with an advanced graphical editor which enables precise and fast creation of a three-dimensional model of the damaged bridge span and offers graphical presentation of the results of the load capacity analysis. Effective algorithm of static and strength analysis allows simultaneous modelling of various defects with non-limited intensity, extent and location.