Title: Testing and Analysis of Trimmer Brackets (Headers) Incorporated within Hollow-Core Floors

Author(s): David F. Hodge, Brian D. O’Rourke, John J. Murphy, and Joseph R. Harrington

Publication: Structural Journal

Volume: 113

Issue: 6

Appears on pages(s): 1153-1164

Keywords: finite element analysis; headers; hollow core; precast concrete; trimmer brackets

DOI: 10.14359/51689016

Date: 11/1/2016

Abstract:
One method of forming large openings within hollow-core (HC) floors is to use steel trimmer brackets (headers). These brackets span between slabs on either side of an opening, thereby providing support for a shorter slab. These brackets are referred to in design documents such as the Precast/Prestressed Concrete Institute (PCI) Manual for the Design of Hollow Core Slabs, but no clear guidance is given on their design. While it is clear that the bracket has to support the self-weight of the slab, it is unclear what level of additional live load is supported by the bracket once the concrete keyway joints between the slabs are filled and have gained strength. This paper details a testing program and an extensive finite element (FE) analysis study that have been undertaken to establish the magnitude of live loads applied to the brackets together with the load-transfer interaction at the slab bracket interface.