Engineering Commons^™

Evaluation Of 50’ Frp Truss Bridges With Timber Decks, Maxwell Browning Carey

Graduate Theses, Dissertations, and Problem Reports

Fiber-reinforced polymer (FRP) composites have become mainstream structural materials and are being utilized in many different structural applications because of their outstanding thermos-mechanical properties and other characteristics. These characteristics include exceptional corrosion resistance, energy absorption, durability, high strength-to-weight, stiffness-to-weight ratios, and others. Also, FRP composites are cost effective especially when accounting for the service life of such a material.

In this study, testing and analysis were performed at both the component as well as a structural system levels. Herein, two FRP truss bridges of different widths with 50 ft. spans underwent extensive testing and analysis in accordance with AASHTO specifications. …

Euplectella Aspergillum’S Natural Lattice Structure For Structural Design & Stability Landscape Of Thin Cylindrical Shells With Dimple Imperfections, Zoe Y. Sloane

Masters Theses

The first portion of this thesis assesses the structural application of a bracing design inspired by the deep-sea sponge, Euplectella Aspergillum. Many studies have investigated the natural strength found in the unique skeletal structure of this species. The braced design inspired by the sponge features square frames with two sets of cross-braces that are offset from the corners of each frame, creating a pattern of open and closed cells. This study reports the results of multiple Finite Element Analysis (FEA) computations that compare the described bracing pattern to a more common bracing design used in structural design. The designs …

A Comprehensive Protocol For Inspection And Assessment Of Aging Steel Bridges: Experiments, Computations And 3d Laser Scanning Of Field Corroded Girders, Georgios Tzortzinis

Doctoral Dissertations

According to a recent evaluation, our nation's infrastructure has increasingly presenting signs of deterioration with some elements exhibiting significant deficiencies in conditions and functionality. Regarding the transportation network condition, from the over than 600,000 bridges which are included in the National Bridge Inventory, 46,154 of them are characterized as structurally deficient with the backlog of bridge rehabilitation needs estimated at US$125 billion. Among the many aspects of structural deficiency, corrosion is considered a common cause, both for reinforced concrete and steel bridge deterioration. For steel bridges, corrosion has historically triggered bridge failures resulting to fatalities and injuries. To prevent similar …

Impacts Of Using Tubular Sections In Open Web Steel Joists, Hollis (Cas) L. Caswell V

Honors Theses

Open web steel joists are lightweight structural trusses used in place of I-beams to support long-span floors and roofs of open space buildings. Their slender geometry makes them highly efficient in resisting flexure, but susceptible to out-of-plane buckling in a failure mode known as lateral-torsional buckling. This failure can be avoided by running lateral bracing between joists called bridging or potentially by using tubular sections to build up the joists rather than angle sections.

It is possible that a joist design using tubular cross-sections could require less bridging and prevent the need to use erection bridging for initial joist construction. …

Biomechanics Of Trees Under Extreme Wind Loading Events, Mojtaba Dargahi

Electronic Thesis and Dissertation Repository

For urban planners, arborists and foresters, understanding tree stability under self-weight and applied loads from wind and snow is important when developing management strategies to reduce the risk of damage from these abiotic agents. Current predictive approaches are generally empirical and based on a posteriori surveys of failures. A more rigorous engineering approach to understanding response phenomenon in trees subjected to extreme winds has been attempted herein. The size of trees and their architecture (shape and structure) greatly influence their mechanical stability under dynamic loading. Considering trees as porous media, wind loads on them are affected by their resistance to …

Critical Buckling And Post-Buckling Behavior Of Thin-Walled Liners Encased By Underground Pipelines In Saturated Soils, Zhaochao Li

Doctoral Dissertations

"This study aims to investigate the structural stability of thin-walled liners encased in functionally-obsolete underground pipelines in saturated soil under external hydrostatic pressure, a concentrated load, temperature change or their combination, and develop a simplified circular arch model of thin-walled liners when not constrained by the pipelines. The friction and adhesion on the interface between a liner and its constraining surface (pipeline or grouting), and the pressure gradient on deeply-buried pipelines are neglected. The critical buckling load of elastic liners is analytically derived under a plane strain condition using the principle of minimum potential energy. The analytical solution is either …

Steel Compression Members With Partial-Length Reinforcement, Morgan Herrell

Electronic Thesis and Dissertation Repository

Steel wide-flange columns in existing truss bridges may be built-up with flange cover plate reinforcement to increase compressive capacity. This thesis investigates the use of partial-length steel cover plates about column mid-height to improve the weak-axis buckling resistance.

The present research first reviews literature concerning the Euler buckling of members with partial-length reinforcement. Inelastic buckling is simulated by 3-D finite element analysis accounting for cover plate length, cover plate area, bolt hole perforations, yield stresses, residual and locked-in dead load stresses, and initial out-of-straightness. The model is validated by a load test of a full-scale column with bolted reinforcement plates. …