STRUCTURAL ASSESSMENT AND STRENGTHENING OF REINFORCED CONCRETE COLUMNS UNDER HORIZONTAL BI-AXIAL CYCLIC LOADING

Publications

Seismic Rehabilitation of RC Columns Under Biaxial Loading: An Experimental Characterization

Publication . Pinheiro Rodrigues, Hugo Filipe; Arêde, António; Furtado, André; Rocha, Patrício

The main purpose of this paper is to present an experimental campaign of different strategies for seismic repair and retrofit of RC columns previously subjected to biaxial cyclic loading actions and evaluate the benefits concerning their structural behaviour when again subjected to biaxial cyclic loading. Column rehabilitation was performed in order to improve the ductility and/or strength characteristics and it was obtained through increasing the concrete ductility conditions, with efficient jacketing, or increasing the amount of longitudinal and transversal steel. The aim is, therefore, to contribute in developing and calibrating a procedure that enables the evaluation of the efficiency of different retrofit solutions, their possibilities and fields of application. The results are presented in terms of shear-drift, stiffness degradation, ductility and energy dissipation. The retrofitted results will be compared with the results of the original one, deducting about the structural efficiency by each type of retrofit technique adopted.

2015-08Journal article

Open access

Numerical modelling of RC strengthened columns under biaxial loading

Publication . Rodrigues, Hugo; Furtado, André; Arêde, António; Varum, Humberto

During an earthquake, the reinforced concrete (RC) structures are subjected to deformations that may lead their structural elements to exceed the corresponding resistance limit state, forcing them to have nonlinear responses. The application of realistic numerical models that can represent the non-linearity of each structural element requires full examination and calibration. Furthermore, simplified numerical approaches that can represent the seismic behaviour of original and strengthened RC elements are of full importance. For this, the experimental tests are useful to calibrate the numerical models, and thus to capture as well as possible the real response of the elements. The main goal of this work is to evaluate the efficiency of a simplified numerical approach to represent strengthened RC columns with steel and CFRP jacketing, subjected to biaxial horizontal loading. The numerical modelling efficiency will be evaluated by comparing the numerical results with the experimental ones in terms of shear-drift hysteretic behaviour, initial stiffness and stiffness degradation, maximum strength and energy dissipation. The results shows a good performance of the numerical models, mainly for the RC columns strengthened with CFRP jacketing technique.

2016-05-09Journal article

Open access

Seismic behavior of RC building structures designed according to current codes

Publication . Mosleh, A.; Rodrigues, Hugo; Varum, H.; Costa, A.; Arêde, A.

Earthquakeswhich recently occurred in highly populated regions showthat existing buildings constructed without appropriate seismic resisting characteristics may constitute as an important source of risk and may cause economical loses and casualties. It is recognized the progress of the knowledge in earthquake engineering in the last decades. In this paper, two 6 irregular storey buildings were studied consisting of frame structures, representative of the common practice in Portugal, i.e. designed without considering earthquake actions. Push-over and non-linear time history analyses were done, with non-inear 3-D models in longitudinal and transverse directions. The building responseswere analyzed in two different levels: global and local. For the global response analyses: max displacement, inter-storey drift (IS drift), floor rotation for each storey and base shear were compared. For local response four columns were chosen and the variation of axial load in terms of base shear and drift as well as the biaxial demand was considered. The result shows that most variation of axial load happens in corner, facade-X, facade-Y and centre column respectively. It is noteworthy that by increasing the initial axial load the biaxial demand decreases. The seismic vulnerability was analyzed for earthquake of different return periods, and the seismic demands were compared with limit proposed in international codes and conclusion are drafted in terms of safety. The vulnerability assessment based on seismic codes clearly shows that the building 2 presented a better performance with low inter-storey drifts. The main goal of this study is considering the application andmethodology for the seismic assessment of existent real buildings. In fact this is an important topic, to understand the seismic vulnerability of certain particularities in existing buildings to assure that the common observation can be applied for a prototype building, especially irregular ones. Also one of the major observations in this study is the comprehension of the effect and importance of biaxial loading in columns and the influence of the axial load variation, relating the position of the columns in plan and in height.

2016-08Journal article

Restricted access

Seismic behavior of strengthened RC columns under biaxial loading: An experimental characterization

Publication . Pinheiro Rodrigues, Hugo Filipe; Arêde, António; Furtado, André; Rocha, Patrício

Abstract The main purpose of this work it to present an experimental campaign of different strengthening strategies of RC columns, and evaluating benefits concerning their structural behavior for cyclic loading. 9 RC columns were tested, two of them without strengthening and seven composed by strengthened columns by CFRP or steel plates jacketing. The aim is, therefore, to contribute for developing and calibration a procedure that enables the evaluation of the efficiency of the strengthening strategies, their possibilities and application. It was also an objective of this work to explore the possibility of using this techniques on the improvement of existing buildings performance.

2015-10Journal article

Restricted access

Keywords

Experimental assessment,Strengthening,Cyclic multiaxial tests,Numerical modelling, Engineering and technology ,Engineering and technology/Civil engineering

Funding agency

Fundação para a Ciência e a Tecnologia, I.P.
Fundação para a Ciência e a Tecnologia, I.P.

Funding programme

5876-PPCDTI
Concurso para Projectos de I&D em todos os Domínios Científicos - 2008

Funding Award Number

PTDC/ECM/102221/2008