Internal Blast Test of a Reinforced Concrete Structure
Lynsey Reese, Ph.D., P.E.; NAVFAC EXWC; Port Hueneme, CA, USA
Michael Oesterle, Ph.D., P.E.; NAVFAC EXWC; Port Hueneme, CA, USA
Michael Newberry; Syscom, Inc.; Pueblo, CO, USA
Keywords
Internal Blast, Protective Design, Rebar Coupler, Rebar with End Plates
Abstract
Multiple tests were performed on a RC structure to measure performance of a wall with threaded rebar couplers and
rebar with anchor plates compared to a baseline wall with conventional reinforcing lap splices and connection details.
The tests were performed at the Hardened Internal Blast Structures (HIBS) facility at Tyndall Air Force Base. The test
setup consisted of a detonation room with a roof slab, floor slab, and four walls that separated it from four witness
rooms. One wall had a doorway size opening that allowed gaseous detonation products to vent out of the room. The
first two tests used a single charge that was initiated in the center of the room, equidistant from each wall. The last
test used two charges next to each wall being analyzed. The blast effects on the walls consisted of multiple shock
reflections and quasi-static gas pressure. The results of the tests demonstrate the efficacy of new rebar technologies
for use in protective structures subject to blast. This paper will summarize all of the tests completed, performance of
new rebar technologies and discuss technology gaps and future work for implementation in current protective design
criteria.
Introduction
Naval Facilities (NAVFAC) Engineering and Expeditionary Warfare Center (EXWC) and Air Force Civil Engineer
Center (AFCEC) conducted three internal blast tests that were designed to demonstrate that RC walls with threaded
mechanical couplers and rebar with end plates exhibit an equivalent response as a conventional RC wall design with
lap splices and hooked rebar. The goal of the tests was to produce enough inelastic response in the walls to achieve a
maximum support rotation greater than two degrees, where support rotation,
, is defined as:
e = atan(
2∆
)
Equation 1
L
where,
∆ = Peak Displacement
L = Span
A value of e equal to two degrees is significant because that is the allowable limit on support rotation for RC walls
providing personnel protection for Protection Category 1 as specified in Unified Facilities Criteria (UFC) 3-340-02
[1].
A schematic that displays how the rebar technologies are implemented into a wall section is shown in Figure 1.
Protective construction designs may be exposed to external and/or internal blast loads where the former is generally
characterized by a single pressure pulse and the latter consists of a short duration shock pressure with multiple
reflections and a quasi-static gas pressure. The walls in this experiment were loaded by an internal blast load because
