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There are a significant number of historic masonry buildings and monuments in seismic areas all over the world that need to be retrofitted. Conventional methods of seismic rehabilitation conflict with the appearance of the masonry element and cannot be employed in the case of monumental buildings where the facade and finishing are decorative or where the exposed masonry defines the character of the structure. Centercore strengthening method has been developed in recent decades and is used in various projects of seismic rehabilitation. However, due to the lack of sufficient experimental and numerical investigation, there is no analytical model to predict the behavior of masonry components retrofitted using this technique. In this research, the material properties of conventional brick masonry used for the construction of Iranian historic buildings and monuments were obtained through base material tests. Afterward, two masonry walls were tested under reversed cyclic in-plane loading. The results showed that centercore method improved the cyclic in-plane behavior of the specimens including ultimate lateral strength and energy dissipation. Moreover, based on flexure theory an analytical model is proposed for prediction of ultimate lateral capacity of masonry walls and piers strengthened by centercore technique, associated with rocking and toe-crushing mechanisms. In addition, regarding dowel action of reinforcing bars and using “Beams on elastic foundation analogy”, a simple formula is proposed to predict the dowel action capacity of centercore rebar and hence, the diagonal crack strength of the retrofitted wall. Comparing the values calculated by the proposed models with available experimental data, showed that the proposed models accurately predicted the ultimate lateral capacity of the specimens.

The test results on eight two-span deep beams made of self-compacting concrete (SCC) are presented and discussed in this paper. The main parameters investigated were the shear span-to-depth ratio, and the amount and configuration of steel reinforcement. All beams failed due to a major diagonal crack formed between the applied mid-span load and the intermediate support separating the beam into two blocks: the first one rotated around the end support leaving the other block resting on the other two supports. Both concrete compressive strength and web reinforcement had a major effect in controlling the shear capacity of the beams tested. For the shear span-to-depth ratio considered, the vertical web reinforcement had more influence on the shear capacity of the specimens than the horizontal web reinforcement. The shear provisions of the ACI 318M-11 are unconservative for most of the beams tested. Comparisons of test results with the strut-and-tie model (STM) suggested by ACI 318M-11, EC2 and CSA23.4-04 showed that the predictions are reasonable for continuous deep beams made with low and medium compressive strength. Although the equation suggested by ACI 318M-11 is very simple, its prediction is more accurate than the STM suggested by different design codes.

The deflection of reinforced concrete (RC) beams with low span-effective depth ratios can be attributed equally to shear and flexural deformations. Although truss models can be used to evaluate shear deformation, their prediction accuracy is strongly dependent on how the diagonal crack angle is estimated. This paper presents the results from an experimental test of nine RC beams that failed in shear and had low span-effective depth ratios (i.e., a / h 0 3 ). It then proposes a multi-angle truss model for predicting ultimate shear deformation while considering the effect of the bending moment variation along the span on diagonal crack angles. An empirical formula is also presented to predict the shear stiffness degradation of RC beams up to the ultimate state through regression analyses. Numerical results show that the proposed multi-angle truss model can be used to predict the shear deformation of RC beams with low span-effective depth ratios with reasonable accuracy.

The objective of this study is to experimentally and analytically estimate the influence of web openings in reinforced concrete deep beams. Thirty-two reinforced high-strength concrete deep beams with or without openings were tested under two-point top loading. Test variables included concrete strength, shear span-to-depth ratio, and the width and depth of the opening. Test results indicated that the strengths at diagonal crack and at peak were closely related to the angle of the inclined plane joining the support and the corner of the web opening. Also, the influence of concrete strength on the ultimate shear strength remarkably decreased in deep beams with openings rather than solid deep beams. From comparisons of predictions and test results, the equations proposed by Kong and Sharp, and Tan, Tong and Tang would be suitable for reinforced high-strength concrete deep beams with openings and θ 3 ≥ 3 0 ∘ .