Does the shear strength of reinforced concrete beams and slabs depend upon the flexural reinforcement ratio or the reinforcement strain?

Beam tests are conducted to investigate the effect of the reinforcement ratio, ρ, and the shear span to depth ratio, a/d, on the shear strength of reinforced concrete beams and slabs without stirrups. The a/d ratio is shown to have a very significant effect on shear strength at both low values of a/d (where failure is governed by strut-and-tie mechanisms) and large values of a/d (where failure is governed by breakdown in beam action). Increases in ρ associated with increases in a/d such that the strain, or M/ρVd ratio, is kept constant will result in constant failure shear stresses. Shear design methods that do not account for a/d (e.g., ACI Committee 440) cannot predict the observed experimental behaviour, whereas the general method of the CSA A23.3 code can. Using the ACI 440 equation for Vc may reduce the economic competitiveness of fibre-reinforced polymer reinforcement versus steel reinforcement

Prevalence of Hepatitis C Virus (HCV) Coinfection in HIV Infected Individuals in South India and Characterization of HCV Genotypes

Purpose: To determine anti-HCV antibodies and genomic subtype of HCV in 1487 confirmed human immunodeficiency virus (HIV) positive samples. Methods: A total of 1487 confirmed HIV-positive samples were tested for anti-HCV antibodies by using a third generation ELISA kit (Ortho 3.0) and by RT PCR for HCV. HIV and HCV coinfected samples were selected for HCV genotyping by RFLP and subtyping with NS5-type specific primers. Results: A total of 1487 HIV-infected serum samples were screened for HCV infection, of which, a 1443 (97.04%) were negative and 45 (3.02%) were coinfected. HIV-HCV coinfection was predominant in the age group 41-50 years (51.1%). HCV genotyping and subtyping was done for the 45 HCV RNA-positive specimens of which genotype 1 was observed in 31 (68.8%) and genotype 3 was observed in 14 (31.1%) subjects. Further subtyping analysis showed the genotype 1b in 23 (51.1%), 1a in eight (17.7%), 3a in 10 (22.2%) and 3b in four (8.8%) subjects. Conclusion: HIV and HCV seroprevalence is higher in South India, and the most prevalent genotype in coinfection was genotype 1b