Strengthened Structural Members and Structures: Analytical Assessment

Reinforced concrete (RC) jacketing is a common method for retrofitting existing columns with poor structural performance. It can be applied in two different ways: if the continuity of the jacket is ensured, the axial load of the column can be transferred to the jacket, which will be directly loaded; conversely, if no continuity is provided, the jacket will induce only confinement action. In both cases the strength and ductility evaluation is rather complex, due to the different physical phenomena included, such as confinement, core-jacket composite action, preload and buckling of longitudinal bars. Although different theoretical studies have been carried out to calculate the confinement effects, a practical approach to evaluate the flexural capacity and ductility is still missing. The calculation of these quantities is often related to the use of commercial software, taking advantage of numerical methods such as fibre method or finite element method. This paper presents a simplified approach to calculate the flexural strength and ductility of square RC jacketed sections subjected to axial load and bending moment. In particular the proposed approach is based on the calibration of the stress-block parameters including the confinement effect. Equilibrium equations are determined and buckling of longitudinal bars is modelled with a suitable stress-strain law. Moment-curvature curves are derived with simple calculations. Finally, comparisons are made with numerical analyses carried out with the code OpenSees and with experimental data available in the literature, showing good agreement.

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“…(8) and (13) have to be set equal to zero, and furthermore if < , Eqs. (9) and (14) are as well equal to zero.…”

Section: Equilibrium Of the Sectionmentioning

confidence: 99%

Strength and ductility of RC jacketed columns: A simplified analytical method

Minafò

Trapani

Amato³

2016

Engineering Structures

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“…Most reinforced concrete (RC) buildings in southern Europe were built in the first half of the 20 th century to carry only gravity loads, by implementing the allowable stress design philosophy which did not allow any control of the failure mode and the corresponding deformation capacity of the individual members [1]. Νon-uniform distribution of stiffness and/or mass along the height of the building, poor material quality, and insufficient reinforcement detailing, are some of the main deficiencies that substantially increase the vulnerability of the existing building inventory when exposed to natural hazards, such as earthquakes.…”

Section: Introductionmentioning

confidence: 99%

“…In case of old type detailing columns, the bar slenderness ratio s/Db (s is the stirrup spacing and Db is the bar diameter of the longitudinal reinforcement), which reflects the stability of compression reinforcing bars supported laterally by stirrups, is generally between 10 and 50 [1]. Based on the work of previous researchers [3][4][5][6], for s/Db < 6 and bars with significant strain hardening, axial load-carrying capacity is greatly enhanced beyond the yielding load, thus inelastic buckling of reinforcing steel bars is expected to occur.…”

Section: Introductionmentioning

confidence: 99%

Structural performance of RC columns retrofitted with steel-reinforced grout jackets under combined axial and lateral loading

Thermou

Papanikolaou

Hajirasouliha

2021

Engineering Structures

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“…flexural strengthening of beams) or a new R/C member in various retrofit techniques (e.g. jacketing, infill walls) entails issues related to the connection between existing and newly cast concrete [1][2][3]. The response of the composite member, and subsequently of the whole structure, depends largely on the response characteristics of the interface, since shear transfer occurs.…”

Section: Introductionmentioning

confidence: 99%