City Research Online

Abstract

Impact loads result when a structure is hit by a missile. The two major considerations in designing for impact are the limitation of local damage and the control of the overall response of the target structural element. Local damage may include penetration, perforation, scabbing and/or punching shear in the region of the impact on the structure. Overall response includes flexure and reaction shear in the structure. Since the analytical prediction of local damage effects is extremely difficult, damage formulae have been developed on an empirical basis. These formulae depend on many parameters which may be classified into two groups, either missile parameters or target parameters. Two of the target parameters, the amount of reinforcing steel and maximum size of aggregate are not considered in the existing empirical formulae to determine critical perforation and scabbing velocities. The principle aim of the research reported in this thesis is, therefore, to find a term accounting for the level of reinforcement to be included in the formulae and to establish the influence of the maximum size of aggregate on the value of missile impact velocity causing scabbing or perforation. The research undertaken involved an experimental programme of sixty-four individual tests. The tests were concerned with the influence of the two parameters previously mentioned upon the perforation and scabbing of model, steel reinforced concrete targets. The test rig was especially designed using high pressure compressed air to accelerate a steel missile along a barrel to impact upon the target. This system can produce a variety of impact forces by either varying the applied pressure or the mass of the missile. Chapter One discusses the local effects and the overall dynamic response caused by high velocity impact upon reinforced concrete targets. The evaluation of the yield line method of analysis for design to resist high velocity impact is mentioned. The objectives and scope of the proposed research are also discussed . Chapter Two contains a literature review on procedures for determining local missile effects. The chapter considers and compares the existing empirical formulae. Also mentioned in Chapter Two are the experimental investigations into the effects of reinforcement and the associated model similarity requirements for impact conditions. The design and construction of a high velocity impact testing facility and the instrumentation associated with the facility are described in Chapter Three. Chapter Four discusses the fabrication of specimens and the test procedure. An account of the results obtained from the experimental programme is given in Chapter Five and Chapter Six discusses the development and application of the new perforation and scabbing formulae. Empirical formulae have been proposed to account for the amount of reinforcement. A general discussion of the results and the conclusions drawn from the experimental results and some recommendations for future research work are given in Chapter Seven and Eight respectively.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Departments:	Doctoral Theses School of Science & Technology > School of Science & Technology Doctoral Theses School of Science & Technology > Engineering

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