Interaction of MSE Abutments with Bridge Superstructures under Seismic Loading \u2013 Shaking Table Tests

65A0556This report presents results from shaking table tests on half-scale mechanically-stabilized earth (MSE) bridge abutments. The testing program consists of five tests where the direction of shaking is in the longitudinal direction of the bridge beam, and one test where the direction of shaking is perpendicular to the bridge beam. The longitudinal shaking tests include a baseline configuration and a parametric study of different configurations to investigate the effects of bridge surcharge stress, reinforcement spacing, reinforcement stiffness, and steel reinforcement on the seismic response of MSE bridge abutments. Experimental design of the scale model followed established similitude relationships for shaking table testing in a 1g gravitational field, including scaling for of geometry, reinforcement stiffness, backfill soil modulus, bridge surcharge stress, and characteristics of the earthquake motions. Facing displacements, bridge seat settlements, accelerations, vertical and lateral stresses, reinforcement strains, and contact forces between the bridge beam and bridge seat were measured for different instrumented sections to evaluate the three-dimensional dynamic response during a series of applied shaking motions. Results indicate that reinforcement spacing and reinforcement stiffness have the most significant effects on the facing displacements and bridge seat settlements for dynamic loading conditions

Development of Bridge Column Longitudinal Reinforcement in Oversized Pile Shafts

Publisher Copyright: © 2016 American Society of Civil Engineers.This paper presents an experimental investigation to determine the embedment length required for longitudinal reinforcement in a bridge column extending into an oversized pile shaft, and the amount of transverse reinforcement required for the pile shaft to prevent premature bar anchorage failure due to concrete splitting induced by bar slip. Four full-scale column-oversized pile assemblies were tested under quasi-static cyclic lateral loading. The test specimens had different embedment lengths for the column reinforcement, different amounts of transverse reinforcement in the piles, different sizes of longitudinal bars, ranging from No. 8 to No. 18 (25 to 57 mm) bars, and different column-to-pile diameter ratios. All column-pile assemblies behaved in a ductile manner with plastic deformation occurring near the base of the columns despite some cone-shaped fractures and tensile splitting cracks occurring in the top portion of the piles. The test results show that the embedment length for the column reinforcement can be significantly reduced as compared to that required in current design specifications. The study also shows that an engineered steel casing designed according to a formula proposed here can effectively confine the pile shaft and significantly reduce splitting cracks.Peer reviewe

Molecular Modeling and Simulation: Force Field Development, Evaporation Processes and Thermophysical Properties of Mixtures

To gain physical insight into the behavior of fluids on a microscopic level as well as to broaden the data base for thermophysical properties especially for mixtures, molecular modeling and simulation is utilized in this work. Various methods and applications are discussed, including a procedure for the development of new force field models. The evaporation of liquid nitrogen into a supercritical hydrogen atmosphere is presented as an example for large scale molecular dynamics simulation. System-size dependence and scaling behavior are discussed in the context of Kirkwood-Buff integration. Further, results for thermophysical mixture properties are presented, i.e. the Henry’s law constant of aqueous systems and diffusion coefficients of a ternary mixture