Prestressed Concrete Design - 11 - Example 2 - Prestress Loss Estimation w/ AASHTO and PCI Handbook

This example problem is in Module 11 of my Prestressed Concrete Design course (Prestress Loss). This example goes through how to calculate prestress loss of a Florida I-Beam (FIB) using the AASHTO LRFD (2017) Refined Method and PCI Handbook Method (2010). There is a composite cast-in-place deck with this section.

[@bowenyang5239]

Hi Dr. David. Thanks for the presentation. Consider that some DOTs require refined analysis to use the transformed section properties. We don't need to add elastic shortening loss at the end if we use transformed section properties, right? Thanks

[@davidgarber1664]

Hi Bowen. Good comment. You are correct. You do not need to add elastic shortening loss if you use transformed section properties to find your stresses. Elastic deformations are implicitly accounted for when using transformed section properties. You can use your jacking stress for finding release stresses and jacking stress minus long-term loss when finding stresses at other times.

[@bowenyang5239]

@@davidgarber1664 Thanks very much, Dr. David. Got it! That makes sense to me!

[@nandaganeshkudva5382]

Design a pre-stressed concrete beam as Type - 1 member to carry a
superimposed load of 12kN/m over a simply supported span of 25m. The
permissible stress in compression for concrete at transfer and working
loads are 14M/mm2 and 12N/mm2 respectively. Initial stress in pre-
stressing cable is 1000N/mm2
. Loss of pre-stress is 20%. Adopt Freyssenet
cables each of 12 wires of 5mm diameter
Can you solve this above problem

[@NeerajKumar-yj2ty]

Can u give the link for this 2017 version code book

[@davidgarber1664]

AASHTO LRFD Bridge Design Specification 8th Edition (store.transportation.org/Item/PublicationDetail?ID=3888). There is a 9th Edition that is now available as well (store.transportation.org/Item/PublicationDetail/4403?NoCategory); I have not updated examples for this edition yet.