Papers by Keyword: Structural Identification

Abstract: The fighter planes of the fifth generation, as compared to the fourth, has increased the composite materials use since high mechanical properties enhance the operational performance. However, composite materials present some negative characteristics such as damage progression, leading to delamination or matrix failure. This phenomenon often results in an unknown behaviour. This paper deals with the delamination phenomenon after casual low energy impacts. On different specimens, we performed different investigations through dynamic characterization, followed by modal parameters elaboration. After completing the first phase an opportune simulation model by FEM was developed to compare the obtained results whose values were in agreement with the real case.

Abstract: In the present article non-destructive testing evaluation of the existing damage evolution has been applied to some buildings of the medieval town of Craco (Matera, Italy) and, in particular, to the Normand tower. Actually the little town of Craco is totally abandoned as a consequence of the activation of the landslide motions of its soil depth. Nevertheless, the Normand tower still stands because it is located on a stable and stiffer foundation ground. The tower was built in the XII century. It is 20 m tall and has a symmetric square plan, with dimensions 11 m x 11 m; it was built for defense against enemy attacks. Inside the tower a cistern in reinforced concrete was placed in 1949. It is not connected to the structural walls of the tower; however it represents an obstacle for installing the damage detection equipment and sensors. In this article a preliminary study on the masonry structure of the Normand tower is carried on. A finite element numerical model has been developed and a modal analysis has been performed. The final aim of the research is to find out the evolutionary stage of the cracks and to propose a possible retrofit of the tower.

Abstract: The paper presents an overview on the timber structures of the Royal Palace of Naples. Focusing on the roofs of the Historical Apartment, located at the second level of the palace, different structural typologies are illustrated. The structural identification was achieved starting from an extensive in situ survey, aimed at assessing materials, conservation state, geometries and static schemes. Therefore 3D FEM models of the study systems as whole were set up and the structural analyses carried out, allowing to catch the weaknesses in terms of strength and deformation capacities; the safety checks were performed according to Eurocode 5 provisions. Finally, on the basis of the acquired knowledge, the appropriate retrofitting techniques were suggested [1, . In particular, with reference to the Diplomatic Hall (II), details of the realized restoration interventions, based on mixed technologies, are presented [.

Abstract: The work presented a structural identification method based on recurrent neural network and auto-regressive and moving average model. The proposed approach involves two steps. The first step is to build a recurrent neural network to map the complex nonlinear relation between the excitations and responses of the structure-unknown system by on-line learning . The second step is to propose a procedure to determine the modal parameters of the structure from the trained neural networks. The dynamic characteristics of the structure are directly evaluated from the weighting matrices of the trained recurrent neural network. Furthermore, a illustrative example demonstrates the feasibility of using the proposed method to identify modal parameters of structure-unknown systems.

Abstract: A new drop hammer was designed and used for multiple reference impact testing of two bridges. The drop hammer utilizes a multiple-rebound control system for successfully applying a single impact with repeatable high-level force for bridge testing. Signal analysis results indicate that the drop hammer provides a higher signal-noise ratio and a better coherence even when the response signals are subject to pollution due to traffic on the bridge. Modal flexibility was computed by using the impact data from the drop hammer, and meaningful deflected shapes could be generated demonstrating the potential of the envisioned structural assessment system.

Abstract: The main purpose of this paper is to present the possibilities of applying data mining methods to the problem of structural identification of complex systems, focusing on the static structural system properties. In this paper we will define the main set of problems of structural identification and propose the way of their solution by means of data mining methods. A specific solution to selected problems is demonstrated on the model designed in the Matlab program. In the framework of experiment based on the results of simulation, we will identify the existence of internal relations in the system and analyze the degrees of their dependencies.

Abstract: Experimental data was collected for structural identification (St-Id) of an old bridge: (1) static displacement and strain measurements taken under proof-load level, and; (2) multi-reference impact test (MRIT) data from one of the spans of a three span, cast-in-place reinforced concrete (RC) T-beam Bridge. MRIT was used to generate the modal data for computation of modal flexibility and displacement profiles. The St-Id procedure used during this application was designed to mitigate epistemic uncertainty in the data interpretation process. Successful results from MRIT demonstrated the reliability of applications for bridge condition assessment based on impact testing.

Abstract: A finite element modelling of a masonry building prototype is illustrated in this paper. A computational analysis describing the dynamic behavior of the structure is presented in order to characterize some dynamical features of the system under the effect of harmonic forces of different intensity. The structure is represented by a two-story masonry building characterized by a regular floor plan. The finite element modelling of the structure intends to reproduce an experimental test of the masonry building subject to a harmonic force input supplied by a vibrodyne. Frequency response functions corresponding to the frequency load inputs are reported for different monitored nodal points of the finite element mesh. In this way by comparison with the experimental results obtained in a parallel study it is possible to suitably assess the calibration of the parameters for characterizing the dynamical behaviour of the masonry structure.

Abstract: In the present paper an experimental study has been performed on a masonry building prototype and some preliminary experimental results are illustrated for analyzing the structural behavior of a masonry building prototype subject to harmonic forces of different intensity. The physical model used for the laboratory test is a two-story masonry building characterized by a regular floor plan. The structure test is subjected to a harmonic force input supplied by a vibrodyne. The experimental results are aimed at characterizing the dynamic response of the masonry building subject to harmonic forces in order to describe the bahaviour of the masonry building under the predominant actions of a seismic input.

Abstract: This work presents the dynamic tests on a retrofitted masonry arch bridge. The Gresal Bridge, located in the North-East of Italy, was highly exposed to seismic hazard, due to the slenderness of its high piers. A retrofit intervention has been carried out, and a new rc slab has been built under the pavement, anchored to the piers with high strength vertical ties and restrained at the abutments, to create a new resistance arrangement withstanding inertial forces. The dynamic behaviour has been initially assessed with numerical models comparing the response of the bridge before and after the repair, and has subsequently been tested by the Output-Only technique to detect the variation of the modal response induced by the strengthening intervention. The dynamic tests have shown the structure to be more rigid than expected and, after calibration, a good agreement to exist between the numerical frequencies and the experimental records captured on the retrofitted bridge.