Ambient Vibration Tests of Two Prestressed Reinforced Concrete Highway Overpasses

Author(s):  
Carlo Pellegrino ◽  
Mariano Angelo Zanini ◽  
Flora Faleschini ◽  
Filippo Andreose ◽  
Klajdi Toska ◽  
...  
Buildings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 39 ◽  
Author(s):  
André Furtado ◽  
Nelson Vila-Pouca ◽  
Humberto Varum ◽  
António Arêde

Following the strong earthquake on April 25, 2015 in Nepal, a team from the University of Porto, in collaboration with other international institutions, made a field study on some of the most affected areas in the capital region of Kathmandu. One of the tasks was the study of a high-rise settle of buildings that were damaged following the earthquake sequence. A survey damage assessment was performed to a 15-storey infilled reinforced concrete structure, which will be detailed in the manuscript. Moreover, ambient vibration tests were carried out to determine the natural frequencies and corresponding vibration modes of the structure. The main aim of this manuscript is to present a numerical study concerning the influence of the masonry infill walls in the structure seismic response. For this, three numerical models were built discriminating the situations with and without damage and nondamaged infill walls. Validation and calibration of the numerical model was ensured by comparing the numerical frequencies with those obtained from ambient vibration tests. In addition, linear elastic analyses were carried out, using real accelerograms from the Gorkha earthquake to assess and quantify the major differences between the models in terms of inter-storey drifts ratios, inter-storey shear forces and seismic loadings.


2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Sergio Vincenzo Calcina ◽  
Laura Eltrudis ◽  
Luca Piroddi ◽  
Gaetano Ranieri

This paper deals with the ambient vibration tests performed in an arch dam in two different working conditions in order to assess the effect produced by two different reservoir water levels on the structural vibration properties. The study consists of an experimental part and a numerical part. The experimental tests were carried out in two different periods of the year, at the beginning of autumn (October 2012) and at the end of winter (March 2013), respectively. The measurements were performed using a fast technique based on asynchronous records of microtremor time-series. In-contact single-station measurements were done by means of one single high resolution triaxial tromometer and two low-frequency seismometers, placed in different points of the structure. The Standard Spectral Ratio method has been used to evaluate the natural frequencies of vibration of the structure. A 3D finite element model of the arch dam-reservoir-foundation system has been developed to verify analytically determined vibration properties, such as natural frequencies and mode shapes, and their changes linked to water level with the experimental results.


1978 ◽  
Vol 104 (5) ◽  
pp. 983-999
Author(s):  
Ahmed M. Abdel-Ghaffar ◽  
George W. Housner

2018 ◽  
Vol 3 (3) ◽  
pp. 39
Author(s):  
Marcos Chávez ◽  
Fernando Peña ◽  
Claudia Cruz ◽  
Gustavo Monroy

This article presents a study on the structural behavior of the Government Building that is part of the old Lecumberri Palace and which currently houses the Mexican General Archive of the Nation. This building was inaugurated in 1900 and closed in 1976, after serving as a prison for 76 years. It was reopened in 1982 after it had undergone several remodeling works. The construction is made of brick masonry with lime mortar. It is supported by a deposit of overly compressible high-plasticity clays. The main problems of this building are the appearance of cracks in both interior and exterior walls, and moisture in the ground floor, caused by differential settlements. The study entailed a geometric and a damage survey as well as ambient vibration tests in order to determine the dynamic properties of the construction. The data obtained was used for the making of a model that, using the finite element method, was analyzed under different load conditions. This study has focused on the overall response with the assumption of smeared crack damage. According to the results, the building’s safety was deemed as acceptable. It has the capability to withstand seismic actions as established by the Mexican Building Code due to the high density of its walls and the resulting stiffness, which infer that the fundamental vibration period of the building would be distant from the predominant vibration period of the soil. This highlights the idea that the building’s critical condition is constituted by the differential settlements, which cause damage in the construction.


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