Basic Prestressed Concrete Design Part 5: Calculating Strength-Basic Prestressed Concrete Design

Video Transcription

Video Summary

This video is the fifth session of a basic pre-stressed concrete design course. In this session, the instructor continues working on a design example and focuses on the calculation of the ultimate moment for both a rectangular beam with straight strands and a rectangular beam with harp strands. The goal is to be able to compute the nominal moment and check for flexural strength at critical locations along the beam. The session also covers the concepts of tension control, compression control, and transition sections, as well as the effect of harp strands on moment capacity. The instructor explains the assumptions and calculations used to determine flexural strength of reinforced concrete beams, including the strain profile and the stress-strain behavior of pre-stressing steel. The approximate method for determining the stress in the pre-stressing strand at ultimate flexural strength is demonstrated using equations from the American Concrete Institute (ACI) 318 code. The video provides step-by-step calculations, discusses the role of the fee factor, and emphasizes the importance of checking the development length regions at the ends of the beam. In conclusion, the section passes the flexural strength check at mid-span for both the straight strand and harp strand configurations.

Keywords

pre-stressed concrete design

ultimate moment calculation

rectangular beam

straight strands

harp strands

flexural strength

tension control

compression control

transition sections

stress-strain behavior

ACI 318 code