Analysis and Design of Shear Capacity of Sisal Fibre-Reinforced Concrete Member in Rectangular Cross-Section

This article presents the study of reinforced concrete columns strengthened using a partial jacket consisting of a 35mm self-compacting concrete layer added to its most compressed face and tested in combined compression and uniaxial bending until rupture. Wedge bolt connectors were used to increase bond at the interface between the two concrete layers of different ages. Seven 2000 mm long columns were tested. Two columns were cast monolithically and named PO (original column) e PR (reference column). The other five columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and other columns had a 155 mm by 250mm cross section after the strengthening procedure. Results show that the ultimate resistance of the strengthened columns was more than three times the ultimate resistance of the original column PO, indicating the effectiveness of the strengthening procedure. Detachment of the new concrete layer with concrete crushing and steel yielding occurred in the strengthened columns.

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Mesoscopic damage evolution on bonding interface and its influence on macroscopic performance deterioration of reinforced concrete member

International Journal of Computational Materials Science and Engineering ◽

10.1142/s2047684119500052 ◽

2019 ◽

Vol 08 (02) ◽

pp. 1950005

Author(s):

Ying Wang ◽

Yuqian Zheng ◽

Xuan Wang

Keyword(s):

Reinforced Concrete ◽

Bonding Strength ◽

Element Model ◽

Bonding Interface ◽

Interfacial Damage ◽

Concrete Member ◽

Steel Bar ◽

Reinforced Concrete Member ◽

Bonding Property ◽

Performance Deterioration

Slip or debonding of bonding interface is the key cause of the performance degradation or failure of the reinforced concrete (RC) member. In this paper, based on Monte Carlo method, a mesoscopic finite element model composed of mortar, coarse aggregate and steel rebar was established to consider the mesoscopic damage on the bonding interface and its influence on macroscopic performance deterioration of RC specimen. The results show that the simulation results fit well with experimental data. Higher initial interfacial damage results in lower bonding strength and smaller final displacement. Higher mortar modulus could greatly improve the initial bonding property and bonding strength, but slightly increase the final damage. Compared with the RC specimen model with plain steel bar, the model with deformed steel bar shows a longer duration of nonlinear increase for drawing force and lower bonding strength. When confinement is applied, the coalescence of damage zones is prevented due to the effect of thread. Therefore, the application of confinement could increase the bonding strength and the initial bonding property.

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Analysis of the behavior of reinforced concrete columns strengthened with sleeve wedge bolts and a self compacting concrete layer

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952015000200003 ◽

2015 ◽

Vol 8 (2) ◽

pp. 88-99

Author(s):

M. G. Marques ◽

A. P. A. R. Liserre ◽

R. B. Gomes ◽

G. N. Guimarães

Keyword(s):

Reinforced Concrete ◽

Cross Section ◽

Rectangular Cross Section ◽

Concrete Columns ◽

Concrete Surface ◽

Self Compacting Concrete ◽

Reinforced Concrete Columns ◽

Concrete Layer ◽

Strength Capacity ◽

Strengthening Technique

Strengthening of reinforced concrete columns by jacketing is one of the most common structural rehabilitation techniques in Brazil. For adequate performance, it is necessary, among others, to avoid detachment of the new concrete layer (strengthening material) from the old concrete substrate when the strengthened member is again in service conditions. This paper describes the test results of eight reinforced concrete rectangular columns subjected to combined compression and one-axis bending to evaluate the efficiency of using sleeve wedge bolts across the new concrete/old concrete interface to avoid detachment. The strengthening technique, in this case, consists of adding a layer of self-compacting concrete to one face of the column. Two columns tested were monolithic and named PO (original column) e PR (reference column). The other six columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and its results gave information about column behavior without the use of strengthening. Column PR had a 155mm by 250 mm rectangular cross section and its cross section dimensions matched the strengthened columns but it was cast monolithically. To improve bond conditions between the existing concrete and the new concrete, the concrete surface was roughened and the outermost aggregate was exposed using hydro jetting. Holes along the concrete surface were made to insert the wedge bolts responsible for increasing the bond between the two concrete surfaces. The difference among the six strengthened columns was the position and amount of bolts used. Results indicate that the position and amount of the bolts alters significantly the strength capacity of the columns, since premature rupture by concrete detachment was delayed.

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