Protective Construction with Reinforced Earth

The objective of this research is to develop a simple analytical method that characterizes plane shock wave propagation through reinforced earth and the dynamic interaction with modular retaining wall panels. The shock wave was initiated as a velocity boundary condition. The exact solution was obtained by the Laplace transform method. A step-by-step design procedure based on the limit state concept is proposed. Because of the impulsive nature of ground shock. the maximum response of the wall panel and reinforced soil system depends mainly on the capacity and rate of energy absorption and dissipation of the system. Therefore, the connection between wall panels and soil reinforcement, and soil reinforcement itself should be ductile beyond the proportional limit. Furthermore, the soil reinforcement should possess a high elastic tensile modulus to minimize the wall panel displacement

Equipment Fragility Due to Shock Response

Because of its simplicity, the shock response spectrum has become widely used as a means of describing the shock responses and fragilities of structures and equipment. This paper focuses on the drawbacks of using the shock response spectrum for defining equipment shock tolerance. A cantilever beam with a tip mass was used to model a hypothetical piece of equipment subjected to strong ground motion such as that caused by an explosion. The exact solution from a detailed modal analysis shows that multiple modes of response were excited. Contributions from higher modes can be more predominant than that from the fundamental mode. Assuming the total response of equipment is predominantly in the first mode can lead to significant error. Current shock spectrum procedures for equipment fragility assessment are inadequate, not only because of the physical limitations of shake table tests, but also because of the lack of a reliable analytical model

Equipment Fragility Due to Shock Response

Because of its simplicity, the shock response spectrum has become widely used as a means of describing the shock responses and fragilities of structures and equipment. This paper focuses on the drawbacks of using the shock response spectrum for defining equipment shock tolerance. A cantilever beam with a tip mass was used to model a hypothetical piece of equipment subjected to strong ground motion such as that caused by an explosion. The exact solution from a detailed modal analysis shows that multiple modes of response were excited. Contributions from higher modes can be more predominant than that from the fundamental mode. Assuming the total response of equipment is predominantly in the first mode can lead to significant error. Current shock spectrum procedures for equipment fragility assessment are inadequate, not only because of the physical limitations of shake table tests, but also because of the lack of a reliable analytical model

Ground Shock Resistance of Mechanically Stabilized Earth Walls

A simple analytical method has been developed that characterizes plane shock wave propagation through reinforced soil and the dynamic interaction between soil and retaining wall panels. The shock wave due to an explosion in the backfill was modeled as a velocity boundary condition at a standoff distance from the wall. The exact solution to this problem was obtained using the Laplace transform method. Full-scale explosive test data from 4.6-m high and 24-m wide reinforced soil walls were used to validate the analytical methodology. The accuracy of the analytical method has further been verified by finite element analysis. The method is adequate for the response analysis of mechanically stabilized embankment walls under ground shock due to an explosion in the backfill

Sympathetic vibration due to co-ordinated crowd jumping

In assembly structures or places where crowds may gather such as dance halls, theaters, gymnasia and stadia, the loading is almost entirely caused by human activities. Structural resonance or near resonance and the resulting vibrations causing discomfort of spectators have often been observed during a rock concert or a sporting event. Recent research efforts have focused on developing load models to quantify the dynamic loading effects induced by individuals and groups up to 40 people. The lack of coherence of motion from a large crowd, the so-called ‘‘group effect’’, has been quantified based on simulations. The simulation results and the load models thus developed should be verified against actual field data from assembly structures before they are adopted into building codes and standards

STRUCTURAL CONCRETE MIX FOR CONSTRUCTION FOR ELECTROMAGNETIC WAVE/PULSE SHIELDING

Conductive concrete mixtures are described that are configured to provide EMP shielding and reflect and/or absorb, for instance, EM waves propagating through the conductive concrete mixture. The conductive concrete mixtures include cement, water, conductive carbon material, magnetic material, and metallic conductive material. The conductive carbon material may include conductive carbon particles, conductive carbon powder, and/or coke breeze. The metallic conductive material may include steel fibers, and the magnetic material may include taconite. The conductive concrete mixture may also include supplementary cementitious materials (SCM). A method of making a concrete structure includes pouring a concrete mixture to form conductive concrete, and positioning a first conductive screen within the conductive concrete proximate to an exterior surface of the conductive concrete. The method also includes positioning a second conductive screen within the conductive concrete in electrical contact with the first conductive screen

STRUCTURAL CONCRETE MIX FOR CONSTRUCTION FOR ELECTROMAGNETIC WAVE/PULSE SHIELDING

Conductive concrete mixtures are described that are configured to provide EMP shielding and reflect and/or absorb, for instance, EM waves propagating through the conductive concrete mixture. The conductive concrete mixtures include cement, water, conductive carbon material, magnetic material, and metallic conductive material. The conductive carbon material may include conductive carbon particles, conductive carbon powder, and/or coke breeze. The metallic conductive material may include steel fibers, and the magnetic material may include taconite. The conductive concrete mixture may also include supplementary cementitious materials (SCM). A method of making a concrete structure includes pouring a concrete mixture to form conductive concrete, and positioning a first conductive screen within the conductive concrete proximate to an exterior surface of the conductive concrete. The method also includes positioning a second conductive screen within the conductive concrete in electrical contact with the first conductive screen