An experimental and numerical assessment of the behavior of geogrid-reinforced concrete columns.

Abstract

Geogrids are geo-synthetic materials that have been established as an effective method for the strengthening of infrastructure applications and rehabilitation of slope stability problems. This study presents the results of experimental and analytical investigations on the performance of concrete columns internally wrapped with different types of Geogrids. The use of Geogrids as confinement material in the reinforced concrete columns is easier and less laborious since it is not as rigid as conventional steel reinforcement. Reinforced Concrete columns were wrapped with three different types of materials: uniaxial geogrids, biaxial geogrids, and steel hoops. The confined and unconfined (control) specimens were loaded in uniaxial compression. Strain gauges are used to qualitatively and quantitatively study the displacement and strain fields on the composite surface. Axial load and axial and lateral strains were obtained to evaluate stress-strain behavior, ultimate strength, stiffness, and ductility of the wrapped specimens. Results show that internal confinement of concrete by geogrids sheets can significantly enhance (1) the strength, (2) ductility, and (3) energy absorption capacity of the concrete specimens. An analytical model to predict the entire stress-strain relationship of concrete specimens wrapped with geogrids was developed. The finite element software package (ADINA) has been used to model reinforced concrete columns under axial stress. However, the proposed study consists of three distinct models. In the first model, the behavior is that of unconfined plain concrete. Biaxial Geogrids behavior is quantified as transverse reinforcement in the second model. In the last model, the reinforced concrete column is confined with Uniaxial Geogrids as transverse reinforcement. Comparison between the experimental and analytical results indicates that the model provides satisfactory predictions of the stress-strain response.