Shear strengthening design

Usually, for shear design the well-known classical truss model is used. The shear strengthening design also requires knowledge and understanding of the cmcial failure modes of the externally bonded shear reinforcement (EBSR). 

In the following sections, the design of flexural and shear strengthening as well as confinement are described. Note that these design methods are still under development and that all equations in these sections are presented without safety factors. In an actual design, safety factors must be applied. 

The value of the design strength of shear strengthened members can be computed... 

Mofidi and Chaallal (2011) have discussed shear strengthening of RC beams with externally bonded FRP composites their paper also reviews the design provisions of the latest versions of the major design gnidelines related to shear strengthening of RC beams with FRP, which are ... 

Similar to the design of flexural strengthening, the following states for the shear design of reinforced concrete (RC) members can be distinguished as the stmctural loads increase ... 

Several equations for the concrete contribution can be found in the relevant literature. However, this equation describes the design shear resistance of a RC member without shear reinforcement. It is important to note that this definition for the concrete contribution is different from the definition of State r given above in this section. To determine Erc, the load at the first shear crack should be calculated. Additionally, all the usual design verifications for RC (failure of the concrete struts, shift of moment line, etc.) have to be considered. For ductility reasons, the member should have a minimum internal shear reinforcement ratio, otherwise strengthening is not recommended. 

Ibiantafillou, T. C. and C. P. Antonopoulos (2000). Design of concrete flexural members strengthened in shear with FRP./owraa/ of Composites for Construction 4(4) pp. 198-205. 

Chaallal, O., Nollet, M. J. and Perraton, D. (1998), Strengthening of reinforced concrete beams with externally bonded fiber-reinforced-plastic plates Design guidelines for shear and flexure , Canadian Journal of Civil Engineering, Vol. 25, Issue 4, pp. 692-704. 

Other complex processes present themselves the interaction of dislocations with each other and other crystal defects. Fig. 15 shows an example of twin boundary that can be grown on a specially designed template. Such boundaries are known to be very effective in the strengthening of materials [45], and colloidal crystals again offer an opportunity to observe the interaction between boundary and dislocation (pileup, decomposition, transmission,. ..) in a unique, direct fashion. Perhaps the most complex plastic deformation is that of amorphous materials. Here, the hard-sphere colloidal glasses allow direct observation of the local shear transformations that govern the plastic flow of these materials. That hard spheres make such... 

The enhancement of strength and stiffness is alternatively achieved by selective or large-scale strengthening of structural members or by the addition of new elements that can resist either partially or fully the seismic actions (e.g., reinforced concrete shear walls, steel trusses, infill walls, etc.). In this case, particular attention should be given to the design of the foundation due to the increase of both the structural mass and the seismic loads. 

The analytical model presented in section Analytical Model for R/C Jacketed Columns explicitly accounts for the slip at the interface between the existing member (core) and the jacket. The transfer of normal and shear stresses in the interface between the external layers of the jacket and the existing member determines the composite action developed by the strengthened members (Thermou et al. 2007). An alternative to this approach is presented in section Simplified Analytical Expressions for R/C Jacketed Columns where simplified analytical expressions in combination with the monolithicity factors may be used for designing the retrofit scheme. 

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