Axially loaded reinforced concrete columns are hardly exist in practice due to the development of some bending moments. These moments could be produced by gravity loads or the lateral loads. First, the current paper presents a detailed analysis on the overall structural behavior of 15 eccentrically loaded columns as well as one concentrically loaded control one. Columns bent in either single curvature or double curvature modes are tested experimentally up to failure under the effect of different end eccentricities combinations. Three end eccentricities ratio were studied, namely, 0.1b, 0.3b and 0.5b, where b is the column width. Second, an expression correlated the decay in the normalized axial capacity of the column and the acting end eccentricities was developed based on the experimental results and then verified against the available formula. Third, based on the equivalent column concept, the equivalent pin-ended columns were obtained for columns bent in either single or double curvature modes. And then, the effect of end eccentricity ratio was correlated to the equivalent column length. Finally, a simplified design procedure was proposed for eccentrically loaded braced column by transferring it to an equivalent axially loaded pin-ended slender column. The results of the proposed design procedure showed comparable results against the results of the ACI 318-14 code.

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The main target of this article is to find out the most applicable strengthening technique to change the brittle punching shear failure of slab–column connection to a ductile one. The considered strengthening technique uses the combined effect of the internal single-leg stirrups and a thin layer of ultra-high-performance strain hardening cementitious composite material provided in either tension or compression side. Thus, 12 slab specimens divided into four groups were prepared and configured. It was found that the slab provided with properly anchored single-leg stirrups with a cross-shaped thin layer of ultra-high-performance strain hardening cementitious composite material at the compression side proved the most efficient technique among all the considered configurations. This technique enabled the slab to sustain a punching load of about 2.38 times that of the control unstrengthened slab. In addition, it exhibited ductile failure showing strain hardening and softening plateaus. Finally, the experimental shear resistances of all the strengthened slabs were compared against the design resistances stipulated by different design standards such as the ECP 203-2007, ACI 318-14, DIN 1045-1, and EC2-2004 codes. It can be concluded that the failure characteristics stipulated by the DIN 1045-1 code showed the most rational results compared with those of the experimental findings.

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