Engineering Commons^™

Electrospinning Processing Techniques For The Manufacturing Of Composite Dielectric Elastomer Fibers, Rani Elhajjar

Civil and Environmental Engineering Faculty Articles

Dielectric elastomers (DE) are novel composite architectures capable of large actuation strains and the ability to be formed into a variety of actuator configurations. However, the high voltage requirement of DE actuators limits their applications for a variety of applications. Fiber actuators composed of DE fibers are particularly attractive as they can be formed into artificial muscle architectures. The interest in manufacturing micro or nanoscale DE fibers is increasing due to the possible applications in tissue engineering, filtration, drug delivery, catalysis, protective textiles, and sensors. Drawing, self-assembly, template-direct synthesis, and electrospinning processing have been explored to manufacture these fibers. Electrospinning …

Polymer Geogrids: A Review Of Material, Design And Structure Relationships, Rani Elhajjar

Civil and Environmental Engineering Faculty Articles

Geogrids are a class of geosynthetic materials made of polymer materials with widespread transportation, infrastructure, and structural applications. Geogrids are now routinely used in soil stabilization applications ranging from reinforcing walls to soil reinforcement below grade or embankments with increased potential for remote-sensing applications. Developments in manufacturing procedures have allowed new geogrid designs to be fabricated in various forms of uniaxial, biaxial, and triaxial configurations. The design flexibility allows deployments based on the load-carrying capacity desired, where biaxial geogrids may be incorporated when loads are applied in both the principal directions. On the other hand, uniaxial geogrids provide higher strength …

Novel Adhesive Anchoring System Through Engineered Interface, Hua Liu, Jian Zhao

Civil and Environmental Engineering Faculty Articles

This report describes a study of an innovative adhesive anchoring system. The weak link in the load transferring path of adhesive anchors is at adhesive-concrete (A-C) interface; hence, the innovation is about creating threads/grooves in drilled holes in concrete before the holes are filled with adhesive and anchors are installed. The new anchoring system is expected to improve the robustness of A-C interface and the consistence of adhesive anchors.

The new adhesive anchoring system was verified in this study using both unconfined and confined pullout tests in uncracked concrete. The tests were divided into to two groups, one using traditional …

Impact Of Test Setup On Tensile Behavior Of Adhesive Anchors, Da Luo, Hua Liu, Jian Zhao

Civil and Environmental Engineering Faculty Articles

This report describes a study of adhesive anchors in two types of tension tests. Confined tension (CT) tests are relatively easy to implement; however, the closely placed reaction may create undesirable and unrealistic confining condition to test anchor. Unconfined tension (UCT) tests are then needed to verify the tensile capacities, which usually correspond to lower bond strength than those from CT tests. Therefore, bond strengths obtained from CT tests must be reduced, and a reduction factor of 0.75 has been stipulated in ACI 355.4 document. This reduction factor (alpha_setup) is currently being challenged.

In this study, we attempt to explore …

A Novel Concrete-Based Sensor For Detection Of Ice And Water On Roads And Bridges, Habib Tabatabai, Mohammed Aljuboori

Civil and Environmental Engineering Faculty Articles

Hundreds of people are killed or injured annually in the United States in accidents related to ice formation on roadways and bridge decks. In this paper, a novel embedded sensor system is proposed for the detection of black ice as well as wet, dry and frozen pavement conditions on roads, runways, and bridges. The proposed sensor works by detecting changes in electrical resistance between two sets of stainless steel poles embedded in the concrete sensor to assess surface and near-surface conditions. A preliminary decision algorithm is developed that utilizes sensor outputs indicating resistance changes and surface temperature. The sensor consists …

Survival Analyses For Bridge Decks In Northern United States, Habib Tabatabai, Chin-Wei Lee, Mohammad A. Tabatabai

Civil and Environmental Engineering Faculty Articles

The use of deicing salts in northern regions of the United States is a major contributor to the long-term deterioration of bridge decks. In this study, the 2008 U.S. National Bridge Inventory (NBI) records were used to develop survival models for non-reconstructed bridge decks in six northern states of Minnesota, Wisconsin, Michigan, Ohio, Pennsylvania, and New York. The hypertabastic accelerated failure model was used to develop survival (reliability) and hazard (failure rate) functions for all six states. The NBI parameters included were the deck rating, type of superstructure (concrete or steel), deck surface area, age, and average daily traffic (ADT). …

Design Considerations For Integral Abutment/ Jointless Bridges In The Usa, Ralph G. Oesterle, Habib Tabatabai

Civil and Environmental Engineering Faculty Articles

This paper summarizes results of a major study on jointless bridges sponsored by the U.S. Federal Highway Administration. This study included extensive laboratory and field experiments as well as detailed analytical studies. A set of design recommendations were provided. Jointless bridges have reduced maintenance, improved riding quality, lower impact loads, reduced snowplow damage, and structural continuity for live load and seismic resistance. However, the thermal movements of the bridge and restraint forces from the abutments and piers must be considered and accommodated. The general design philosophy is to build flexibility into the support structures to the extent feasible while providing …