Engineering and Technology Journal

Structural strengthening is a method of application to raise the load-ability capacity of building structures to meet the building's need to carry additional and unexpected loads that were not accounted for in the main design. In this study, Ferro-cement was used for strengthening concrete beams. Three locally available wire mesh types were used with an ordinary cement mortar to strengthen reinforced concrete beams under flexural loading. The results show that using a Ferro-cement layer with wire mesh of 15 mm size square opening has the best effect on increasing reinforced concrete beams' bearing capacity and deflection more than when using the other two types of meshes. The first crack and failure load increases were 72 and 79%, respectively. In contrast, the deflection increased 70 and 51% at the first crack and failure load.

This research work presents a nonlinear finite element investigation on the behavior of high strength fiber reinforced concrete beams. This investigation is carried out in order to get a better understanding of their behavior throughout the entire loading history. The three- dimensional 20-node brick elements are used to model the concrete, while the reinforcing bars are modeled as axial members embedded within the concrete brick elements. The compressive behavior of concrete is simulated by an elastic-plastic work-hardening model followed by a perfectly plastic response, which terminate at the onset of crushing. In tension, a fixed smeared crack model has been used.

The addition of epoxy bending plate to the tension and compression faces or web is an effective technique for flexural or shear strengthening of reinforced concrete beams, also using of steel fibers with concrete improves the structural behavior and increases the moment capacity and shear resistance of the beams. General equations are derived for predicting the bending moment capacity, maximum and balancing reinforcement ratio the equivalent depth of the compression zone for singly and doubly reinforced rectangular sections and T-beams. The results indicate that bending moment capacity increased in beams with steel fibers and composite plates, while the maximum balancing reinforcement ratios are decreased.

In this paper, an extensive study is carried out 18 beams on the behavior of T-beams (8 with web openings, 10 without openings). Compressive strains distribution at the flanged are investigated with the presence of the openings in web to recheck the effective width of flange with real flange width. Parametric study are considered in this paper includes the compressive strength, longitudinal flexuralreinforcement,flangereinforcement,shear reinforcement and theweb openings (location, shape, size). Generally, standard codes of practice have overestimated effective flange width due to concentrated load effect, and codes do not take into account the web openings effect. Based on the results, the enhancement in effective width for each parameter were 9.1%-13.36%(compressive strength),10.1%-13.3%(longitudinal flexural reinforcement),7.6%-18.2%(flange reinforcement),3.35%-5.7%(shear reinforcement), the web openings reduced the effective flange width by 15% (openings at mid span ) and 5% ( openings at quarter span ) and the circular opening gavean optimum effective width better than rectangular opening were located both at quarter span.

Reactive powder concrete (RPC) is a new type of ultra-high strength and high ductility concrete first developed in the 1990's in France. It is recognized as a revolutionary material that provides a combination of ductility, durability, and high strength. In this research work the nonlinear f ini t e element investigation on the behavior of RPC
beams is presented. This investigation is carried out in order to get a better understanding of their behavior throughout the entire loading history. Also, a numerical parametric study was carried out on the RPC beams to investigate the influence of fibrous concrete compressive strength ( ) cf f ¢ , tensile reinforcement ratio ( ) w r , fiber content ( Vf ) and shear span to effective depth ratio (a/d) on the shear behavior and ultimate load capacity of these beams.
The three- dimensional 20-node brick elements are used to model the concrete, while the reinforcing bars are modeled as axial members embedded within the concrete brick elements. The compressive behavior of concrete is simulated by an elastic-plastic work-hardening model followed by a perfectly plastic response, which terminated at the onset of crushing. In tension, a fixed smeared crack model has been
used.

This research work presents a nonlinear finite element investigation on the
behavior of lightweight reinforced concrete beams. This investigation is carried
out in order to get a better understanding of their behavior throughout the entire
loading history.
The three-dimensional 20-node brick elements are used to model the
concrete, while the reinforcing bars are modeled as axial members embedded
within the concrete brick elements. The compressive behavior of concrete is
simulated by an elastic-plastic work-hardening model followed by a perfectly
plastic response, which terminated at the onset of crushing. In tension, a fixed
smeared crack model has been used .The effect of some important parameters
(ƒ'c , rw ,a/d) have been investigated to study their influence on the predicted loaddeflection
curves

This work aim to study the effect of transverse reinforcement , area of splice
bar, concrete cover thickness , rib area and the increasing in concrete strength (highstrength
concrete) on bond strength between concrete and reinforcing spliced bars .
Therefore, a new simple equation is derived for beams with spliced bars and
confined by transverse reinforcement to calculate bond strength and reflects the
effects of these factors .Where many of existing codes and provisions used to
calculate the spliced strength do not include or reflect the influencing of these factors
in bond strength estimation . Based on experimental results from previous works ,
(116) confined beams with spliced bars are investigated in this study , where
concrete compressive strength ( c f ¢
) ranging from 25 MPa to 113.793 MPa ,amount
of transverse reinforcement vary in a wide range and , conventional and high
relative rib area of deformed bars are present in these beams . The proposed method
exceed the limitation of ( f MPa c ¢ £ 69 ) that given by ACI code .Where the
proposed method is examined and applicable for concrete compressive strength up
to 113 MPa . Also, in this work the second root of c f ¢
is examined , as concrete
strength increased with high-strength concrete , to reach a suitable value for both
normal and high- strength concrete and to be more appropriate with the heavy
present of transverse reinforcement . Power of (0.35) is adopted and used in this
work instead of the second root of c f ¢