Investigation of a hollow structural section connection and transfer member for load sharing in anti-ram vehicle barriers

Open Access
Author:
Noveral, Christian James
Graduate Program:
Civil Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 06, 2013
Committee Members:
  • Dr Daniel G Linzell, Thesis Advisor
Keywords:
  • anti-ram
  • barrier
  • finite element analysis
  • HSS
  • hollow structural section
  • connection
  • LS-DYNA
Abstract:
As evidenced by various past and present events involving vehicle delivered explosive device attacks on buildings, efficient and effective anti-ram barrier designs can be very beneficial in protecting structures. Anti-ram barriers put in place to protect structures from moving vehicles follow a different design, analysis, and construction approach than most structures due to the extreme nature of the vehicle impact load. In many situations, it is also important to consider aesthetic implications of anti-ram barriers when completing a design. Hollow structural section (HSS) steel members are very useful for the design of anti-ram barriers because of their efficiency in dealing with torsion or biaxial loads, and their aesthetic and architectural advantages. Certain types of load sharing configurations involving pierced HSS member connections and an HSS transfer member do exist as a nature of the HSS shapes, however their behavior under impact loading is largely undocumented. There existed a need to understand the use of these connections and transfer members parallel to the direction of impact in anti-ram barriers for load sharing purposes. A prototype structure using basic pierced HSS connections and an HSS transfer member was designed and its performance under vehicle impacts was examined parametrically. The prototype structure was designed using a basic plastic collapse analysis. Varied parameters included member sizes, piercing hole sizes, and connection orientation with respect to the piercing member. The prototype structure was examined using finite element (FE) analysis with modeling techniques selected from past modeling of full-scale crash tests and past literature. Additionally the FE models were validated against past full-scale tests of partially restrained moment connections. Results from the validated FE models that examined barrier behavior were presented in the form of member force time histories at important locations and via internal strain energy calculations. These results indicated that the use of a basic pierced HSS connection and HSS transfer member oriented parallel to the direction of impact effectively shared load between bollards in anti-ram barriers. In addition, recommendations for reducing member sizes when using the studied connection and transfer member are provided.