Structural Engineering Commons^™

Isotropic Shrinkage Of Patterned Vacancies Enables Three-Dimensional Nanoprecise Metastructures For Visible Light Applications, Quansan Yang, Gaojie Yang, Takahiro Nambara, Hiroyuki Kusaka, Yuichiro Kunai, Alex C. Matlock, Corban Swain, Brett Pryor, Yannick Salamin, Daniel Oran, Hasindu Kariyawasam, Ramith Hettiarachchi, Dushan Wadduwage, Marin Soljačić, Peter T. C. Soflaei, Edward S. Boyden

Computer Science Faculty Publications

Three-dimensional metastructures with nanoscale feature sizes exhibit unique properties compared with structures with larger feature sizes, but are difficult to fabricate. Here we introduce implosion carving (ImpCarv), a method for photopatterning vacancies of complex geometry throughout materials, followed by isotropic shrinkage (>10-fold). ImpCarv works by photoactivating sensitizers to generate reactive oxygen species that cleave a swollen hydrogel at defined points, followed by controlled shrinkage via dehydration. ImpCarv creates three-dimensional metastructures where the refractive index of each point throughout a material can be specified with nanoscale precision via material presence or absence. By leveraging refractive index programmability for precise phase …

A Review Of Infrared Thermography Applications For Civil Infrastructure, Prabal Shrestha, Onur Avci, Sahabeddin Rifai, Feras Abla, Michael Seek, Karl Barth, Udaya Halabe

Engineering Technology Faculty Publications

Civil infrastructure is continuously subject to aging and deterioration due to multiple factors, which lead to a decline in performance and impact structural health. Accumulated damage on structures increases operational costs and poses significant risks to public safety. Effective maintenance, repair, and rehabilitation strategies are needed to ensure civil infrastructure’s overall safety and reliability. Non-Destructive Evaluation (NDE) methods are utilized to assess latent damage and provide decision-makers with real-time information for mitigating hazards. Within the last decade, there has been a significant increase in the research and development of innovative NDE techniques to improve data processing and promote efficient and …

Elevation-Distributed Multistage Reverse Osmosis Desalination With Seawater Pumped Storage, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

A seawater reverse osmosis (RO) plant layout based on multistage RO with stages located at different elevations above sea level is described. The plant uses the weight of a seawater column from pumped storage as head pressure for RO (gravity-driven multistage RO) or to supplement high-pressure pumps used in RO (gravity-assisted multistage RO). The use of gravitational force reduces the specific energy for RO compared to using high-pressure pumps. By locating the RO stages at different elevations based on demand sites, the total specific energy consumption for RO and permeate transport to different elevations above sea level is reduced from …

Lateral-Torsional Instability And Biaxial Flexure Of Continuous Gfrp Beams Including Warping And Shear Deformations, Waverly G. Hampton

Civil & Environmental Engineering Theses & Dissertations

This dissertation presents an experimental and theoretical study of the lateral-torsional instability and biaxial flexure of Glass Fiber Reinforced Polymer (GFRP) beams including warping and shear deformation effects. The theoretical analysis is based on three simultaneous differential equations of equilibrium with new terms added to account for shear deformation effects. To solve these equations, algorithms based upon a central finite-difference approach are then developed. The experimental study is conducted on a series of single- and multi-span beams subjected to concentrated loads. The predicted beam behavior agreed well with that observed experimentally. The investigation revealed that the ASCE-LRFD Prestandard for pultruded …

Tire-Chip Reinforced Foundation As Liquefaction Countermeasure For Residential Buildings, Hemanta Hazarika, Siavash Manafi Khajeh Pasha, Isao Ishibashi, Norimasa Yoshimoto, Tota Kinoshita, Shigeki Endo, Ashoke Kumar Karmokar, Takuto Hitosugi

Civil & Environmental Engineering Faculty Publications

To prevent vibration-induced and liquefaction-induced damage to residential buildings during earthquakes, a low-cost technique has been developed and described here. It utilizes a mixture of tire chips and gravel as the horizontal reinforcing inclusion under the foundation of residential houses. The horizontal reinforcing inclusion refers to a layer of tire chips and gravel which is placed horizontally beneath the foundation. This mixture of tire chips and gravel provides sufficient bearing capacity to the foundation. In this research, a series of small-scale 1 g model shaking table tests was performed to evaluate the effectiveness of the technique. In addition, cyclic undrained …

Investigation Of Ribbed Dome Including Tuned Mass Damper, Ali Parva

Civil & Environmental Engineering Master's Projects

This research report presents the outcome of an investigation of lightweight ribbed steel dome structure. The proposed ribbed dome structure is studied both numerically and experimentally under static, natural vibration, and base excitation conditions. The base excitation is considered in the form of a sinusoidal as well as seismic loading in the form of a scaled-down 1940 El Centro earthquake. A numerical study of the ribbed dome is also conducted including a tuned mass damper (TMD). The performance of the dome is also compared with that of a hexagonal vertical structure showing a superior response of the dome under seismic …

Efficient Domain Decomposition Algorithms And Applications In Transportation And Structural Engineering, Paul W. Johnson Iii

Civil & Environmental Engineering Theses & Dissertations

Domain decomposition is a divide-and-conquer strategy. In the first part of this dissertation, a new/simple/efficient domain decomposition partitioning algorithm is proposed to break a large domain into smaller sub-domains, in such a way as to minimize the number of system boundary nodes and to balance the work load for each sub-domain. This new domain decomposition algorithm is based on the network’s shortest path solution. Numerical results indicate that the new Shortest Distance Decomposition Algorithm outperformed the most widely used METIS algorithm in 21 out of 27 tested (transportation) examples. In the second part of this dissertation, another new/simple and highly …

Experimental And Predicted Behavior Of Frp Beam-Columns Including Retrofitting, Ali Al-Huazy

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome of a theoretical and experimental study of Fiber Reinforce Polymer (FRP) beam-columns with uniaxial bending and including retrofitting. The research involved the design and fabrication of a testing apparatus which was then used for a series of beam-column tests. Three different types of beam-column cross sections were used, namely, channel section, I-section, and square tube section. Six non-retrofitted beam-columns were tested in addition to two retrofitted ones. The members were subjected to an eccentric vertical load applied through a lever arm generating gradually increasing axial load and uniaxial bending moment up to the maximum load. …

Behavior And Strength Of Pultruded Frp I-Section Columns Including Uniaxial And Biaxial Bending, Emad M. Amin

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome of a study of the behavior and strength of pultruded glass fiber reinforced polymer (FRP) I-section columns including uniaxial and biaxial applied bending moments. Also included in the study is a critical assessment of ASCE-LRFD Pre-standard for pultruded FRP structures in view of the rigorous analysis presented herein. The theoretical solution is based on a system of three coupled differential equations of equilibrium combined with pinned flexural and torsional boundary conditions. Effects of induced warping due to second-order terms as well as initial out-of-straightness are accounted-for in the governing differential equations. Detailed investigations into the …

Effective Cfrp Retrofitting Schemes For Prestressed Concrete Beams, Herish Abdullah Hussein

Civil & Environmental Engineering Theses & Dissertations

This thesis presents a detailed theoretical study of a number of retrofitting schemes for prestressed concrete beams using carbon fiber reinforced polymer (CFRP) sheets to increase flexural strength and ductility. A simply-supported beam subjected to a gradually increasing uniformly distributed load is adopted for the study with a variety of CFRP retrofiring schemes. Three different types of beam cross sections are included for quantifying the influence of CFRP retrofitting when used in high compression regions in addition to CFRP use in high tension areas. To achieve this goal, nonlinear moment curvature relations are developed and coupled with a finite-difference solution …

Static, Vibration Analysis And Sensitivity Analysis Of Stepped Beams Using Singularity Functions, Peng Cheng, Carla Davila, Gene Hou

Mechanical & Aerospace Engineering Faculty Publications

A systematic approach is presented in this paper to derive the analytical deflection function of a stepped beam using singularity functions. The discontinuities considered in this development are associated with the jumps in the flexural rigidity and the applied loads. This approach is applied to static and vibration analyses of stepped beams. The same approach is later extended to perform sensitivity analysis of stepped beams. This is done by directly differentiating the analytical deflection function with respect to any beam-related design variable. The particular design variable considered here is the location of discontinuity in flexural rigidity. Example problems are presented …

Steel Angle Section Members Under Combined Axial Load And Unsymmetric Bending, Maheshchandra Rajasekharan Phanibhushan

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome of an investigation into the experimental and theoretical behavior of steel angle section members under combined axial load and unsymmetric bending. Tests are conducted on a series of six angle section members provided with biaxial pinned-end boundaries about the cross-sectional non-principal axes. The end bending moments and axial load are applied in a quasi-static manner until the member load-carrying capacity is reached. The experimental load-deflection and load-strain curves are recorded. The theoretical analysis is based on a system of both elastic as well as materially nonlinear differential equations. The equations were solved using an iterative …

Plain And Steel-Reinforced Concrete Shear Walls With And Without Cfrp Retrofitting, Ali Mohammed Salih Al Aloosi

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome- of a study of the behavior and strength of plain and steel-reinforced concrete shear walls with and without a window opening and Carbon Fiber-Reinforced Polymer (CFRP) retrofitting. A total of seven tests were conducted using six different shear walls. Each wall was subjected to a gradually increasing static load at one of it's top corners until the maximum load was reached. The load-deflection relations and the walls' failure patterns were observed and recorded. It was found that the window opening in the plain concrete wall reduced the wall load capacity by 18 percent. For the …

Simulation, Visualization And Self-Assessment Tools For Enhanced Engineering Education The Stiffness Matrix Method Module For Structural Analysis, Ahmed Ali Mohammed

Civil & Environmental Engineering Theses & Dissertations

Existing macromedia FLASH software which has extensive and exciting simulation and visualization capabilities is utilized to develop the "Stiffness Matrix Method" (SMM) module, which is one of the new topics ( offered for the first time in Spring 2007 semester) covered in a Structural Analysis I course, offered at the junior level at Old Dominion University. The developed software (under the FLASH environment), including tutorial lectures to explain all necessary theoretical backgrounds, formulas, step-by-step computerized procedures and numerical examples are presented in simple, user friendly, visualized, interactive fashion to enhance the student's learning capabilities. Through numerous graphical visualization and simulation …

Flexural Behavior Of Thermoplastic Beams With And Without Frp Reinforcement, Hilmi Coskun

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the results of an experimental and theoretical study of the flexural behavior of thermoplastic beams with and without fiber-reinforced plastic (FRP) rebars. Tests are conducted on commercially available thermoplastic beams known as Seatimber. The normal stress-strain relations of both the thermoplastic material and FRP rebars are obtained in tension and compression experimentally. These mechanical property curves are then used as part of the input for developing the theoretical moment-curvature relations using an iterative equilibrium procedure. The moment-curvature relations are in turn used for predicting the beam load-deflection curves via the central finite-difference procedure. Behavior predictions are made …

Dynamic Analysis Of Linear Structural System Using Ritz Vector Method And Substructuring Formulation, Vijay R. Modi

Civil & Environmental Engineering Theses & Dissertations

In this study, the substructuring formulation is incorporated into Ritz Vector method to obtain and solve the reduced system of dynamic equilibrium equations. Two-dimensional and three-dimensional truss problems are considered in the present study. The accuracy and computational time using the proposed technique are compared with known solutions. The effect of using different number of substructures and Ritz vectors are also investigated, equations solver is utilized to Moreover, a version of a parallel further enhance the numerical performance of the proposed technique on the FLEX/32 Multicomputer.

Computer-Aided Analysis And Design Of Rectangular Buried Tank Walls And Its Safety Factor Evaluation Based On Yield Line Analysis, Rakiya J. Fatoohi

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the results of a study that determines the true safety factor of underground square reinforced concrete tank walls.

The walls are analyzed and designed by elastic method. The amount and distribution of the reinforcement was determined by use of the alternate design method (working stress) in compliance with all ACI code requirements. The wall's ultimate moment was computed by use of yield line theory assuming non-isotropic reinforcement. The ultimate value of the earth pressure was computed and compared with the elastic analysis and design values to give the true safety factor.

The results of this study indicate …

Structural Sensitivity Analysis On A Parallel Computer, Niu Kian Teck

Civil & Environmental Engineering Theses & Dissertations

Substructuring formulation using adjoint variable approach has been developed for design sensitivity analysis and optimization of large scale structures. In this study, the procedure for statics and sensitivity analysis are re-examined to propose a programming scheme which can be implemented either in a sequential or parallel environment. The computational times of the substructuring formulation using a single processor versus multi-processors are compared to see the effectiveness of the formulation in the concurrent computing environment.

Static And Dynamic Buckling Of Shallow Arches, David D. Loendorf

Civil & Environmental Engineering Theses & Dissertations

The static and dynamic buckling behaviors of a shallow, simply supported sinusoidal arch subjected to both a uniformly distributed step pressure load and a purely impulsive load are considered. Five equilibrium paths are obtained for the arch under static loading conditions. Critical static loads corresponding to two different instability modes and based on characteristics in the load displacement curve are obtained numerically. Critical dynamic loads, corresponding to three different instability modes, are obtained from a numerical procedure in which buckling criteria are based on characteristics in the time response of the structure. The influence of damping on the various dynamic …