What is it about?
This paper presents a comparative study on the transmission length of pre-tensioned concrete members using experiments and standard codes. Also, a case study was presented to understand the influence of tranmission length on the shear resistance of a typical precast hollow-core slab.
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Why is it important?
A significant number of pre-tensioned, hollow core slabs (HCS) without shear reinforcement or stirrups are being used in tall structures and industrial buildings. The shear resistance of HCS is highly dependent on the prestress transferred. Hence, the transmission length is one of the important design parameters. This paper highlights the discrepancy existing among the design equations for transmission length given in the literature and codes. If the design transmission length is shorter than the actual transmission legnth, it could lead to poor shear resistance of the HCS members. This paper finds that some codes underestimate transmission length and provide less conservative shear designs. Based on experimental results, this paper proposes a new empirical equation to the IS 1343 and other codes to arrive at rational and conservative shear designs.
Perspectives
This paper gives an insight about the significance of tranmission length on the shear resistance of the member. It is important for a code to provide adequate tranmission length as it governs the distribution of prestress between the strand and concrete. This eventually influence the shear resistances if the actual transmission length is underestimated and could cause bursting stresses at the end if the actual transmission length is overestimated. Hence, for a PTC systems, rational estimation of transmission length is very important. The codes which do not consider many factors which could influence the transmission length, has to be revised to provide a rational estimation.
Prabha Mohandoss
Read the Original
This page is a summary of: Transmission length of pretensioned concrete systems – comparison of codes and test data, Magazine of Concrete Research, May 2018, ICE Publishing,
DOI: 10.1680/jmacr.17.00553.
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