The Algerian seismic design code (RPA99) recommends a limit on the elastic period as a governing factor in the design process of low and mid‐rise buildings, function of the structural system regardless of the related ductility level. The recommended limit criterion is evaluated through approximate analytical methods using drift limit. The assignable displacement ductility ratio for the force reduction factor is derived from some well established R‐μ‐Tn expressions. The limit period evaluation procedure (proposed in this paper) agrees with a capacity design approach since it allows for adjusting the required resistance demand level function of a ductility level resulting from code's steel recommendations. This will enhance seismic design procedure based on a target‐period approach such as in the Algerian seismic design code RPA99, to fulfil the minimum required two performance levels or to satisfy three performance levels if a damage control is considered. A critical study is carried out considering three regular earthquake‐resistant concrete framed structures and taking into account the specificity of various types of soils, namely rock, firm and soft. A comparison of the obtained results shows clearly that the RPA99 recommended limit is only valid for nude moment resisting frames.

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International audienceAn experimental study has been carried out on damaged rectangular reinforced concrete beams, repaired with near surface mounted carbon fibre reinforced polymer materials. A total of 32 specimens were loaded to failure in a 4-point flexural test. The parameters considered are the rate of damage (20, 40 and 60%), the rate of strengthening and the type of strengthening materials (rods and strips). Concrete compressive strain, carbon fibre reinforced polymer strain, ultimate strength and load-deflection have been recorded to evaluate the response of the specimens. Results clearly demonstrate that the strengthening with near surface mounted carbon fibre reinforced polymer can enhance the structural performance of reinforced concrete beams in terms of both maximum strength and deformation. The effects of test parameters are evidenced and compared

Abstract. Abstract. Concrete-filled steel tubes circular section columns are increasingly used in the design of modern multi-stories structures. Investigations developed in recent decades confirm their beneficial use. They are used as a structural component system, given their excellent energy absorption and dissipation, or as a rehabilitation tool for recovery of damaged components after a seismic event. They contribute through their performance to confer high strength to elements, as high ductility and high rigidity, with a remarkable optimization of the used materials. The main objective of this work is to review the principal models characterizing the behavior laws of concrete confined by steel jacket. An analysis based on Samantha model was conducted to highlight the parameters affecting the sectional behavior, and to evaluate the gains in strength and deformation. A section strength capacity investigation is presented. Results are compared with some codes recommendations. This type of structure can be used in Algeria for rehabilitating old buildings, or strengthening reinforced concrete columns to improve their structural performance. However, new regulatory measures should be considered in order to introduce this compound element in the construction.

Shear walls are very efficient structural elements to resist lateral seismic disturbance. Despite the aforementioned seismic performance, recent investigations report that they have suffered from significant structural damage after recent seismic activity, even for those complying with seismic provisions. These deficiencies in resistance and deformation capacities need to be explored. This study considers the influence of plastic length Lp, concrete compressive strength f_c28, longitudinal reinforcement ratio ρl, transverse reinforcement ratio ρsh, reduced axial load ν, confinement zone depth CS and focusing on the geometric slenderness λ. The parametric study has been conducted through NL pushover analysis using Peform3D software. The chosen coupled shear-flexure fiber macro model was calibrated with well-known cyclic experimental specimens. The paper points out the discrepancy between the two well-known codes EC8 and ASCE/SEI 41-13. In fact, the value of the slenderness ratio (λ) that trigger the beginning of a purely flexural behaviour recommended by EC8 (λ>2) is very different from the value of the ASCE/SEI 41-13 (λ>3) without accounting for the effect of the reduced axial force. Finally, it was found that RCW capacities are very sensitive to f_c28, ν, ρl, Lp and less sensitive to ρsh and CS. However, (λ) is the most decisive factor affecting the NL wall response. A new limit of slenderness and appropriate deformations of rotations are recommended to provide an immediate help to designers and an assistance to those involved with drafting codes. Doi: 10.28991/cej-2021-03091777 Full Text: PDF