International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Transducers whose outputs are characterized as a charge require signal conditioning to convert the charge produced to a voltage or current for use in instrumentation systems. Blast gauges, in particular, require processing which preserves the transient nature of the data and very fast risetimes, which would otherwise be degraded by long cable runs and parasitic capacitances. A charge amplifier which amplifies and converts a charge to a low-impedance voltage suitable for driving coaxial lines is described, along with theory of operation. Charge amplifiers of the type described are relatively unaffected by temperature and power supply variations, and occupy less than two square inches of printed circuit board space per channel.

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Blast loads on buildings can originate from accidental explosions or from targeted attacks. Design against blast loads has become an increasingly important topic due to the current political climate. Unfortunately, many older buildings are constructed with unreinforced masonry (URM) walls which are particularly susceptible to out of plane failures caused by blast loads. One solution to increase the safety of these buildings is to retrofit them with advanced materials that can increase their out-of-plane stiffness and resistance. This thesis investigates the potential of using a high-performance shotcrete as a retrofit system for URM walls against blast effects. The shotcrete used in this study is made from Engineered Cementitious Composite (ECC), a special type of fiber-reinforced cementitious material, with high ductility and high energy-absorption capacity. The ECC shotcrete replaces aggregates with synthetic microfibers to increase tensile strength and ductility. A welded wire mesh was embedded in the shotcrete to provide ductile behavior. The testing program includes a total of six large-scale unreinforced masonry wall specimens. Two walls were constructed using concrete masonry unit (CMU) blocks to be retrofitted. The first specimen was built as an infill wall, experiencing no axial load, while the second specimen was built as a load bearing wall, with 10% axial load. Four more walls were built out of stone blocks. Two of the stone walls were controls: one infill and one load bearing (4% axial load). The other two stone walls were retrofit with the shotcrete system: one infill and one load bearing (4% axial load). The blast loads were simulated using the University of Ottawa’s Shock Tube. The walls were restrained at the top and bottom with a shear restraint to induce one way bending. Pressure, displacement and strain data were acquired with the use of pressure gauges, LVDT’s, strain gauges and cameras. The specimens were subjected to gradually increasing blast pressures until failure. The performance of the specimens was observed by analyzing the displacement, crack widths, fragmentation and failure mode. The results indicate the benefits of using ECC shotcrete as a retrofit system. The displacements of the retrofit walls were very small compared to the control walls, and fragments were limited. The specimens with axial load were found to have increased resistance. While the failure mode was brittle for the retrofit walls, this can be avoided with the use of a mesh with a larger area of steel. A SDOF analysis was performed to predict the blast response of the test walls. The analysis was done by generating resistance functions for the walls through analytical models. The analysis was found to agree reasonably well with the experimental data.

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Blasts and impacts are two of the severest loads a structure can experience. Blast experimenters, however, have observed that the load imparted to a circular member was lower than the predicted design load. Additionally, numerous investigations have established the superiority of concrete filled FRP tubes (CFFTs) over conventional reinforced concrete members. These observations indicated CFFTs’ potential to resist dynamic blast and impact loads. The experimental and numerical investigations presented in this thesis aimed to demonstrate the suitability of CFFTs to resist blast and impact loads, to determine the parameters that influence their behaviour under such loads, and to develop a design procedure for resisting these loads. The initial numerical investigation determined the reflected blast loading parameters experienced by a circular cross section. The experimental phase consisted of testing twelve full scale specimens, two monotonically, four under impact loading, and six under close-in blast loading. The monotonically tested specimens acted as controls for the entire program. The results of the impact testing investigation were used to develop and validate a non-linear single degree of freedom (SDOF) model. This impact phase also led to the development of relatively simple procedures for designing CFFTs under impact loading using either SDOF modeling or the conservation of energy. Analysis of the blast testing results led to the development of numerical procedures for obtaining an equivalent close-in blast loading for SDOF analysis of CFFTs and Pressure-Impulse diagrams. The use of SDOF modeling and conservation of energy in blast design were also discussed. Finally, a non-linear explicit dynamic model of CFFTs was developed using the commercial software ANSYS Autodyn. This model was verified using the experimental impact and blast test results and used to conduct a parametric study. The results of these investigations indicated that CFFTs were particularly suitable for blast and impact resistant applications, as their geometry diffracted blast waves and the addition of the tube increased their energy absorbing capacity significantly giving them additional strength and ductility. The tube also confined and protected the concrete core and simplified construction. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2014-01-27 15:57:52.768

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Thesis (Ph.D.) -- McMaster University, 1997. / Includes bibliographical references. Also available via World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1928. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 76-80).