Engineering Commons^™

Wide Band-Gap Metamaterials As Seismic Shields, Ashraf Mohammed Daradkeh

Civil Engineering Dissertations

In the past decade, a new paradigm gained popularity among researchers aiming to protect structures from low-frequency seismic vibrations using metamaterials. However, developing a workable design for metamaterials is still challenging, given the various factors such as material availability, size, and shape of its components. This project proposes a new configuration that can widen the attenuation frequency of metamaterials and evaluates the attenuation ability of double-graded metamaterials. The project investigates unit cell parameters such as but not limited to size, density, and modulus of elasticity to finalize a unit cell with the broadest possible bandgap by using common construction material …

Finite Element Approach On Minimization Of Cracks At I-Girder Ends Induced By Prestress, Sangit Rauniyar

Civil Engineering Dissertations

Prestressed I-girders are one of the very commonly and widely used girders for bridges. It is produced at precast plant and transported to bridge site. To produce a prestressed I-girder, strands are first pulled and concrete is poured in I-girder’s formwork. Once the concrete reaches a desired strength, strands are released which induce prestress in I-girder. There are mainly two types of design for I-girders-one that requires debonding of strands at the end of I-girders and another that requires harping of strands at the end of I-girders. The debonding and harping of strands are done to reduce tension at the …

Finite Element Modeling Of Thermal Effect On Airport Slabs, Chuanyue Shen

International Conference on Durability of Concrete Structures

A sub-ground tunnel connecting two concourses of a terminal at Chicago O’Hare International Airport suffered from water leakage. The airport engineers suspected that the problem was caused by high stresses impinging on the tunnel structure by the pavement sections above the tunnel, acting to damage joints and waterproofing membranes that should have prevented such leakage. To provide a fundamental solution to this problem while minimizing the interference with airport operation, a repair strategy needs to be determined based on a clear understanding of the root cause. A preliminary field inspection confirmed that the concrete pavement slabs moved significantly when ambient …

Fatigue Impacts On Hdpe Pipe Material Properties, Marjan Shahrokh Esfahani

Civil Engineering Dissertations

During a pipe’s life cycle, failures occur due to numerous factors such as age, loading conditions, environmental conditions, installation quality, manufacturing procedures, operation and maintenance strategies and so on. Frequent pressure surges or fluctuations in a piping system may cause a fatigue failure as fatigue is one of the most important issues in water pipes due to water hammer impacts. Application of buried High Density PolyEthylene (HDPE) water pipelines has significantly increased in recent years, and PE4710 is a new member of HDPE family. So, there is not yet enough information about PE4710 long-term performance. Due to lack of enough …

Long-Term Management And Condition Assessment Of Concrete Culvert, Zhenting Zou

Dissertations

Infrastructure is the backbone of national security, economic growth, public safety and other aspects of the society. Nationwide, the condition of America’s infrastructure was graded as “D+” by the American Society of Civil Engineers (ASCE) in 2013.

Owners and responsible agencies have employed various cost-effective maintenance and repair methods as well as analytical tools to repair and extend the service life of the infrastructure. However, without a long-term plan, maintenance work can be delayed by lack of funds. Maintenance delay may cause significant reduction in condition state leading to premature failure of the infrastructure. Consequently, a long-term rehabilitation plan is …

A Study On Tibiofemoral Joint Contact Area Stresses Using Finite Element Method, Anjeza Gjini, Altin Bidaj, Enio Deneko, Drilona Disha

UBT International Conference

The joints of the human body act as mechanical or building structures joints. Joints connect different segments by enabling the movement of these segments. The design of a joint that provides durability or static support differs from that one which provides only movement. Joints of the human body, as organic joints, are considered more complex than other types of joints. Finite element models help to comprehend the knee structure behavior under the action of dynamic and static loads. Deformations in the articulating cartilage and the distribution of loads from meniscus provide data to understand the effect of loads in different …

Evaluation Of Live-Load Distribution Factors (Lldfs) Of Next Beam Bridges, Abhijeet Kumar Singh

Masters Theses 1911 - February 2014

A new precast-prestressed cross section was recently developed by a consortium of engineers from the six New England states, New York and members of the northeast region of PCI. The northeast extreme Tee (NEXT) beam is efficient for medium Bridge spans (50 to 80 ft long). Field formwork savings are introduced by having a flange cast integrally during fabrication of the beams at the precasting plant. Job safety is increased because a working platform is created. The flange width of the NEXT Beams can be adjusted during fabrication to accommodate roadways of different widths and skew angles. Because the section …

Comparison Study Between Fem And Sem For Wave Propagation Models Applied To Solids, Shaddy Roberto Castillo Ponton

Open Access Theses & Dissertations

Wave propagation is a field whose application has spread across many disciplines. In the field of structural engineering, wave propagation methods have focused their attention specifically in the area of structural health monitoring and active control of vibrations and noise. Likewise, the development of new methods and their application have been successful in the area of material science with a special emphasis on the field of structural integrity evaluation of anisotropic and inhomogeneous structures (laminated composite structures). The current available analysis tools are inadequate to handle the modeling of complex structures. One-dimensional wave propagation problems in solids are still a …

Historic Bridge Evaluation Using Finite Element Techniques, Helena M. Charron

Masters Theses 1911 - February 2014

The present study examined the application of modern, computer-based analysis methods to two existing historic bridges in Massachusetts. The first bridge featured in this study is the Woronoco Bridge, a reinforced concrete open spandrel arch bridge that was constructed in 1923. It was hoped that a computer-based, parametric study of this bridge would prove it to be deck-stiffened, similar to select bridges of Swiss engineer Robert Maillart. However, the results do not support that there was any intent to reduce bending in the arch as a result of increasing the stiffness of the bridge deck. Instead, the Woronoco Bridge appears …

Eulerian-Lagrangian Two Phase Debris Flow Model, Cora E. Martinez

FIU Electronic Theses and Dissertations

The main objective of this work is to develop a quasi three-dimensional numerical model to simulate stony debris flows, considering a continuum fluid phase, composed by water and fine sediments, and a non-continuum phase including large particles, such as pebbles and boulders. Large particles are treated in a Lagrangian frame of reference using the Discrete Element Method, the fluid phase is based on the Eulerian approach, using the Finite Element Method to solve the depth-averaged Navier–Stokes equations in two horizontal dimensions. The particle’s equations of motion are in three dimensions. The model simulates particle-particle collisions and wall-particle collisions, taking into …

Simplification Of Resilient Modulus Testing For Subgrades, Daehyeon Kim, Nayyar Zia Siddiki

JTRP Technical Reports

Resilient modulus has been used for characterizing the stress-strain behavior of subgrade soils subjected to traffic loadings in the design of pavements. With the recent release of the M-E Design Guide, highway agencies are further encouraged to implement the resilient modulus test to improve subgrade design. In the present study, physical property tests, unconfined compressive tests, resilient modulus (Mr) tests and Several Dynamic Cone Penetrometer (DCP) tests were conducted to assess the resilient and permanent strain behavior of 14 cohesive subgrade soils and five cohesionless soils encountered in Indiana. The applicability for simplification of the existing resilient modulus test, AASHTO …