Analysis of Laterally Loaded Long or Intermediate Drilled Shafts of Small or Large Diameter in Layered Soil
Strain wedge (SW) model formulation has been used for evaluating the response of a single pile or a group of piles in layered soils to lateral loading. The SW model approach provides appropriate prediction for the behavior of an isolated pile and pile group under lateral static loading in layered soil (sand and/or clay). In this study, the authors extend the capability of the SW model to predict the response of laterally loaded large diameter shafts considering 1) the influence of shaft type on the lateral shaft response; 2) the nonlinear behavior of shaft material and its effect on the soilshaft-interaction; 3) developing partial or complete liquefaction in the surrounding soil profile based on far and near-field induced porewater pressure; and 4) vertical side shear resistance along the shaft wall that has a significant contribution to the lateral shaft response.
A Study of Fiber Reinforced Plastics for Seismic Bridge Restrainers
This Innovations Deserving Exploratory Analysis (IDEA) project evaluated the use of fiber-reinforced plastic (FRP) fabrics as restrainers for seismic rehabilitation of highway bridges as an alternative to steel restrainers to reduce bridge hinge movement during earthquakes. Glass, carbon, and glass/carbon hybrid restrainers were fabricated and evaluated in large-scale dynamic laboratory tests. The research work involved (i) tensile tests on FRP strips and on FRP/concrete bond at various loading rates, (ii) FRP restrainer development and dynamic testing, (iii) shake table tests, data analysis, and performance comparison for FRP, steel, and shape memory alloy (SMA) restrainers, and (iv) development of a FRP restrainer design method. The results showed that the FRP strength was insensitive to strain rates and that the FRP/concrete bond was a function of concrete shear strength but insensitive to strain rates. The results also demonstrated feasible methods for flexible restrainer construction and restrainer/concrete bonding. A simplified FRP restrainer design method, considered more realistic than that of AASHTO was proposed that takes into account the dynamic characteristics of a bridge structure.
Geological, mineralogical and chemical characterization of Devonian kaolinite-bearing sediments for further applications in the ceramic (tiles) industry in La Paz, Bolivia
Clay minerals are widely distributed in Bolivia; among them, illitic clays are most common in the Altiplano where they are mined for use in the ceramic industry that has been growing in the last few years. In addition to illitic sediments, kaolinitic sediments have been recently discovered in sedimentary units in the Bolivian Altiplano. Residual ball clay occurrences in Devonian sedimentary units were studied as part of this work. Geological mapping and geophysical studies (ERT and GPR) were done for better understanding the origin of the deposits and were part of a preliminary study of the mineral potential to define the relationship with the host rock. Chemical and mineralogical techniques such as X-Ray Diffraction, Scanning Electron Microscopy and Inductively Coupled Plasma analyses were performed in samples from the studied area to verify the presence of kaolinite. Atterberg limits and behaviour of the raw material in ceramic specimens supported by chemical analyses show that this material is suitable for manufacturing tile ceramics. This study provides fundamental knowledge for deposit exploitation and future generation of an alternative source of employment for the inhabitants of Micaya.