Analysis of the Traffic Induced Vibrations on a 19th Century Heritage Chapel using FEM Modelling

• Type: Article in International Conference Proceedings Book
• Date: 2010

Authors

P. Tamvakou (Author) Other; M.M. Paredes (Author) Other; R.C. Barros (Author) FEUP

Conference proceedings International

Title: Proceedings of The Tenth International Conference on Computational Structures Technology

Pages: 1-16

The Tenth International Conference on Computational Structures Technology

Valencia-Spain, 14 a 17 de Setembro de 2010

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Scientific classification

FOS: Engineering and technology > Civil engineering

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Resumo (PT): To study the consequences of traffic vibrations on a patrimony chapel, a finite element method (FEM) modelling of the chapel and adjoining soil and road was developed using commercial software ANSYS [1]. The dynamic loads corresponding to vehicles moving along the road were simulated and the corresponding maximum displacements accelerations and stresses of some chapel key points were obtained. The dimensions of the heritage chapel are 4.91 m wide, 9.2 m long, 7.15 m high. To include the effect of the adjacent Manor-House, a small wall attached to the eastern side of the chapel in continuity of façade with the chapel southern front wall (9,82 m long), and a big wall attached to the eastern side of the chapel alongside its length (20 m long) were considered. The complex FEM model of the chapel-house-soil-road was meshed with 20-node brick elements. The first 3 modes of vibration had the natural frequencies: f1=16.23 Hz, f2=22.19 Hz and f3=24.85 Hz; they matched (with some accuracy) values obtained by system identification using 4 seismographs at 4 implantation points of the chapel and detecting the motion characteristics induced by ambient vibrations (Miguel [2]). As the hypothetical vehicle moves along the road, its weight is always between 2 road nodes. Some nodes were selected on the walls of the chapel, for which were explicitly calculated the displacements and the accelerations. When the vehicle is near the chapel wall, the displacements begin to increase up to the point that the wall reaches its maximum displacement. Some nonlinear graphs of normal and shear stresses variations were determined for the operating weight of a large hydraulic excavator on tracks as heavy circulating vehicle. Although the chapel structure might look safe for ultimate limit conditions that apparently do not reach critical stress values, the chapel behaviour indicates indexes and conditions which imply reduction or loss of serviceability. The peak sway ratios for this chapel under heavy traffic reached values only characteristic of much slender structures like masonry bell towers (Selby and Wilson [3]). Also, the calculated peak transient horizontal accelerations for several nodes on the west wall, far exceeded the peak recommended value of 42 mm/s2 defined in BS 6472 [4] for adverse human exposure to vibration in buildings. (Paper 140)

Abstract (EN): To study the consequences of traffic vibrations on a patrimony chapel, a finite element method (FEM) modelling of the chapel and adjoining soil and road was developed using commercial software ANSYS [1]. The dynamic loads corresponding to vehicles moving along the road were simulated and the corresponding maximum displacements accelerations and stresses of some chapel key points were obtained. The dimensions of the heritage chapel are 4.91 m wide, 9.2 m long, 7.15 m high. To include the effect of the adjacent Manor-House, a small wall attached to the eastern side of the chapel in continuity of façade with the chapel southern front wall (9,82 m long), and a big wall attached to the eastern side of the chapel alongside its length (20 m long) were considered. The complex FEM model of the chapel-house-soil-road was meshed with 20-node brick elements. The first 3 modes of vibration had the natural frequencies: f1=16.23 Hz, f2=22.19 Hz and f3=24.85 Hz; they matched (with some accuracy) values obtained by system identification using 4 seismographs at 4 implantation points of the chapel and detecting the motion characteristics induced by ambient vibrations (Miguel [2]). As the hypothetical vehicle moves along the road, its weight is always between 2 road nodes. Some nodes were selected on the walls of the chapel, for which were explicitly calculated the displacements and the accelerations. When the vehicle is near the chapel wall, the displacements begin to increase up to the point that the wall reaches its maximum displacement. Some nonlinear graphs of normal and shear stresses variations were determined for the operating weight of a large hydraulic excavator on tracks as heavy circulating vehicle. Although the chapel structure might look safe for ultimate limit conditions that apparently do not reach critical stress values, the chapel behaviour indicates indexes and conditions which imply reduction or loss of serviceability. The peak sway ratios for this chapel under heavy traffic reached values only characteristic of much slender structures like masonry bell towers (Selby and Wilson [3]). Also, the calculated peak transient horizontal accelerations for several nodes on the west wall, far exceeded the peak recommended value of 42 mm/s2 defined in BS 6472 [4] for adverse human exposure to vibration in buildings. (Paper 140)

Language: English

Type (Professor's evaluation): Scientific