2nd EFAST Workshop, Reliable Testing of Seismic Performance

The EFAST project consisted of a design study of a new major seismic testing facility in Europe that will be comparable with important testing installations that are now working or under construction in Japan, U.S.A., China and Taiwan. The presentations by invited experts during the 2nd EFAST Workshop, which was held by the end of the project, emphasized the basic idea that experiments are necessary because reliable engineering cannot still rely only on numerical predictions. The relation between the experimental research and the improvements of the buildings codes in the last decades has also suggested that a consistent experimental activity is fundamental for properly understanding and predicting the real behaviour of complex structural elements. Today in many fields, as in the assessment of nuclear facilities for example, more reliability is required in order to increase the safety, which leads to a newer impulse for experimental testing of components, subsystems, soil-structure interaction effects and so on. The necessity and characteristics of the available testing methods was reviewed with up-to-date examples and studies on aspects such as shaking table, pseudo-dynamic and hybrid testing methods, centrifuge facilities, scale models, soil-structure interaction, control strategies and performance. Within the EFAST design study as it was presented, several solutions are proposed for the future experimental facility, among which the reference one is a laboratory composed, mainly, of a high performance shaking table array and a reaction structure where both traditional (pseudo-static/dynamic) and innovative testing techniques (e.g. real time hybrid testing) can be applied and combined. These shaking tables can be moved in the trench and can be also rigidly coupled between them, if necessary. A large SDOF shaking table for geotechnical studies is also foreseen in such solution. The discussion of the different solutions covered aspects such as costs (including safety, maintenance and operation), demand of experiments, flexibility and performance among others.JRC.G.5-European laboratory for structural assessmen

Preliminary Report to ESFRI Roadmap for the new Research Infrastructure EFAST

The present report provides information useful for the preparation of the application of the new Research Infrastructure EFAST to the ESFRI roadmap. A brief introduction about the EFAST project and the ESFRI open the document. Two sections follow: the first one is devoted to identify the main need in Earthquake Engineering, the second one deals with the current and future testing technologies all around the world. The proposed concept of the EFAST testing facility is then described and the main strategic values are illustrated. Economic aspects about its realisation and the positive fall down on European economy are also discussed. A section dedicated to the impact of EFAST on the scientific community and, more generally, on the whole society conclude the report.JRC.G.5-European laboratory for structural assessmen

A scaled-time test method

The Pseudo-Dynamic Test Method (PDTM) is being developped currently as an alternative to the shaking table testing of large size models. However, the stepped slow execution of the former type of test has been found to be the source of important errors arising from the stress relaxation. A new continuous test method, wich allows the selection of a suitable time-scale factor in the response in order to control these errors, es proposed here. Such scaled-time response is theoretically obtained by simply augmenting the mass of the structure for wich some practical solutions are proposed

Annex: Master Configuration Files

A DLL (Dynamic Link Library) is a file of code containing functions that can be called from other executable code. The advantage of working with DLLs at ELSA PsD Master controller is in the modularity for programming the testing method and algorithm without the need to work with the master.exe program. This new version of DLL allows the implementation of both PsD and Cyclic test, plus strain-rate effect compensation, re-start capabilities and a large variety of security alarms. In this manual the user will find a full explanation of how to use the DLL throughout some simple examples. In this Annex the user can find some other examples coming from real tests carried out at ELSA laboratory.JRC.G.5-European laboratory for structural assessmen

Un nuevo método longitud de arco para estructuras no lineales

En los últimos años el método de longitud de arco ha demostrado ser muy efectivo en la resolución de problemas estructurales no lineales dada su capacidad de manejo de puntos límite y su facilidad en la implementación de un tamaño automático del paso de integración. Sin embargo, existen todavía algunas limitaciones conocidas para este método. En este artículo se presenta una versión diferente que evita una de dichas limitaciones y también son incorporados algunos detalles que pueden dar mayor generalidad a ambas versiones

ELASPSD Data Acquisition and Signal Generator User Manual

The European Laboratory for Structural Assessment (ELSA) belongs to the Joint Research Centre (JRC) of the European Commission. It is one of the units of the Institute for the Protection and Security of the Citizen (IPSC) at the Ispra Site of the JRC. The main facility of ELSA is a large Reaction Wall‐Strong Floor system equipped with powerful servoactuators used to simulate the response of civil full‐size structures submitted to dynamic loads using the ELSAPSD testing system. During a test, the user may want some data to be displayed, analyzed or/and stored in the computer. This can be made through an acquisition object. This manual explains how to use an acquisition starting from the most simple case, which is using an acquisition node with an internal trigger. Each chapter adds new information to the previous one, so it is interesting to read the manual in a sequential order. This manuals refers to the acquisition software of ELSAPSD according to the versions PSDCYC03.DLL and M13.004 of the master controller software and acqui.exe???????

The scaled-time test as an alternative to the pseudo-dynamic test

The stepped and excessively slow execution of pseudo-dynamic tests has been found to be the source of some errors arising from strain-rate effect and stress relaxation. In order to control those errors, a new continuous test method which allows the selection of a more suitable time scale factor in the response is proposed in this work. By dimensional analysis, such scaled-time response is obtained theoretically by augmenting the inertial and damping properties of the structure, for which we propose the use of hydraulic pistons which are servo-controlled to produce active mass and damping, nevertheless using an equipment which is similar to that required in a pseudo-dynamic test. The results of the successful implementation of this technique for a simple specimen are shown here

Hierarchical boundary elements

In this paper we show the possibility of applying adaptive procedures as an alternative to the well-known philosophy of standard Boundary Elements. The three characteristic steps of adaptive procedures, i.e. hierarchical shape functions families, indicator criteria, and a posteriori estimation, can be defined in order to govern an automatic refinement and stopping of the solution process. A computer program to treat potential problems, called QUEIMADA, has been developed to show the capabilities of the new idea

Influencia de las irregularidades de la vía en la respuesta dinámica del sistema vehículo-vía-estructura en puentes de ferrocarril

En el marco de la U.I.C. (Unión Internacional de Ferrocarriles) la Oficina de Investigación y Ensayo (O.R.E) está desarrollando la cuestión D-160, relativa al cálculo de la flecha admisible de los puentes, en función de la confortabilidad de viajeros. El presente artículo expone algunos de los resultados obtenidos con los programas desarrollados en la Escuela Técnica Superior de Ingenieros Industriales de la Universidad Politécnica de Madrid

Modelo de fisuración. Aplicación a estructuras axisimétricas de hormigón armado

El comportamiento mecánico del hormigón sigue siendo un problema no resuelto en cuanto a la modelización según las teorias de la mecánica del continuo, a pesar de tratarse de un material ampliamente extendido en su uso. Una de las facetas más caracteristicas de su comportamiento, la fisuración, representa tal vez el aspecto más dificil de tratar en los modelos bi y tridimensionales. En este articulo se describe un modelo propuesto de comportamiento que salva el compromiso entre complejidad y aplicabilidad: La fisuración es considerada como un deterioro del material -daño, tal vez- y su orientación no es registrada en la historia; al igual que ocurre en la Teoria de la Plasticidad, existe un trabajo de fisuración que sirve para medir el deterioro existente. El modelo es además compatible con la plasticidad como tal, tipica del comportamiento a compresión del hormigón. Dicho modelo, junto con una versión modificada del método de longitud de arco para resolución de problemas no lineales, es implementado y utilizado para la resolución de algunos ejemplos