Browsing by Subject "Finite element analysis"
Now showing 1 - 16 of 16
Results Per Page
Sort Options
Item The adhesive interactions between graphene and substrates by blister tests(2015-12) Cao, Zhiyi, Ph.D.; Liechti, K. M.; Huang , Rui; Ravi-Chandar , K.; Lu, Nanshu; Akinwande, DejiA blister test and associated analysis was developed to characterize the interfacial adhesion between graphene and copper and silicon substrates to which it has been transferred. Chemical vapor deposition grown graphene had been transferred to a highly polished copper or silicon substrate from its seed foil. The graphene/photoresist or graphene/PDMS/photoresist composite film was pressurized with deionized water through a hole in the substrate and the deflection of the membrane was measured by a full field interference method. Different mixed-mode conditions were achieved by varying the thickness of the backing layers. The measured adhesion energy for the graphene/copper and graphene/silicon interfaces showed a strong dependence on the mode-mix. The deflection profiles were modeled by plate, membrane theory and finite element analysis. The variation of energy release rate with blister radius and thickness for graphene/copper and graphene/silicon interfaces were obtained. The traction-separation relations of the graphene/copper interface were determined in the modified blister tests. The blister profiles and normal crack opening displacements were measured by two synchronized camera. Cohesive zone models associated with traction-separation relations were developed to study the damage initiation and crack propagation under various mixed-mode conditions. It was determined that the maximum normal and shear strength, which governed damage initiation, was independent of the mode-mix. The softening parameter, which governed damage evolution, was also independent of the mode mix. The numerical solution for and experimental measurements of the pressure vs. blister radius and deflection, as well as NCOD were in good agreement. A model for the variation of traction-separation relations with mode-mix was developed based on an asperity shielding model. The delamination paths of the graphene/photoresist, and graphene/PDMS/photoresist samples and the quality of graphene after the blister test were confirmed by Raman spectroscopy. The use of pressure could provide a path to large-scale graphene transfer.Item Behavior of the shear studs in composite beams at elevated temperatures(2015-12) Dara, Sepehr; Engelhardt, Michael D.; Helwig, Todd A; Williamson, Eric B; Ghannoum, Wassim M; Ezekoye, Ofodike AIn order to improve the fire safety and at the same time to provide more economical design of composite floors in fire, it is important to understand the behavior of these systems under fire exposure. An important step needed to reach this goal is to better understand the behavior of shear studs in composite beams at elevated temperatures, which was the focus of this research study. Typically, corrugated metal decks are used in construction of composite beams. These decks act as formwork and provide reinforcement for the concrete. For this study, however, the corrugated deck was not included. Rather, this study focused on cases where there is a solid concrete slab over the steel beam. The purpose of this limitation was to first gain a thorough understanding of shear stud behavior under fire exposure for this simpler configuration. This study on shear stud behavior at elevated temperature in solid slabs included both experiments and numerical simulations. The objective of the experimental test was to develop additional data on the load-slip behavior of shear studs in solid concrete slabs at elevated temperatures, and to compare the measured shear stud strength values with the limited test data and code provisions available in the literature. Two different specimen heating scenarios were introduced. One was meant to result in a temperature gradient in the specimen to simulate a fire condition. The other scenario was meant to result in a uniform temperature throughout the specimen for comparison purposes with the other scenario. One of the conclusions was that the shear stud strength and initial stiffness in the shear stud load-slip behavior have strong correlations with bottom of stud temperature, regardless of the heating scenario. Therefore, choosing the bottom of stud temperature as a reference temperature in predicting the shear stud ultimate strength and initial stiffness is reasonable. The objective of the numerical simulations was to develop a finite element (FE) model which can predict the thermal and mechanical behavior of shear studs in solid concrete slabs at elevated temperatures, and to validate the model against the experimental data. Different aspects of modeling the specimen using the general purpose finite element software, Abaqus, were discussed. Results of the analyses were compared with the experimental results of this study. Temperatures resulting from the heat-transfer analysis were found to be in a good agreement with experimental results at some locations in the specimen. However, at some other locations the difference between the experimental and FE results were more than 100 ºC. The existing level of uncertainty in the input data highly contributes to the errors in the temperature results, and emphasizes the difficulty that exists in heat transfer modeling. The load-slip curves found from FE analysis were presented for all the tests. The ultimate strength and the initial stiffness of the specimens were predicted well by the FE analyses. However, the slip capacity did not match between the experiments and FE analyses. Several parametric studies using the finite element model were conducted to investigate the sensitivity of the analysis results to various model parameters, both for heat transfer analysis and structural response analysis. The studied parameters included thermal conductivity of concrete, convective heat transfer coefficient, resultant emissivity, thermal joint conductance coefficient, Concrete Damaged Plasticity model parameters, steel stress-strain curves recommended by two different code provisions, and concrete tensile strength. The current gaps in our knowledge about these parameters were discussed.Item Design and analysis of the Hobby-Eberly Telescope Dark Energy Experiment bridge(2010-05) Worthington, Michael Scott; Nichols, Steven P.; Beno, Joseph H.A large structural weldment has been designed to serve as the new star tracker bridge for the Dark Energy Experiment upgrade to the Hobby-Eberly Telescope at McDonald Observatory. The modeling approach, analysis techniques and design details will be of interest to designers of large structures where stiffness is the primary design driver. The design includes detailed structural analysis using finite element models to maximize natural frequency response and limit deflections and light obscuration. Considerable fabrication challenges are overcome to allow integration of precision hardware required for positioning the corrector optics to a precision of less than 5 microns along the 4-meter travel range. This thesis provides detailed descriptions of the bridge geometry, analysis results and challenging fabrication issues.Item Development of Design Guidelines for Soil Embedded Post Systems Using Wide-flange I-beam to Contain Truck Impact(2012-07-16) Lim, Seok GyuAnti ram perimeter barriers are part of the protection of important facilities such as power plants, air ports and embassies against unrestricted vehicle access. Many different systems can be used to achieve the containment goal. One of these systems makes use of soil embedded posts either single posts if the soil is hard enough or groups of soil embedded posts tied together by beams if the soil is not hard enough for a single post to stop the in-coming truck. The design of these soil embedded posts needs to take account a number of influencing factors which include the soil strength and stiffness, the post strength and stiffness, the mass of the vehicle and its approach velocity. This dissertation describes the work done to develop a set of design recommendations to select the embedment of a single post or group of posts. The post is a steel beam with an H shape cross section: W14X109 for the single post system and W14X90 for the group system with a double beam made of square hollow steel section HSS8X8X1/2. The spacing of the posts for the group includes 2.44 m, 4.88 m, and 7.32 m. The soil strength varies from loose sand and soft clay to very dense sand and very hard clay. The vehicle has a mass of 6800 kg and the velocities include 80 km/h, 65 km/h, and 50 km/h. The design guidelines presented here are based on 10 medium scale pendulum impact tests, 2 medium scale bogie impact tests, 1 full scale impact test on a single post, 1 full scale impact test on a group of 8 side by side posts with a 5.2 m spacing and connected with two beams, approximately 150 4-D numerical simulations of full scale impact tests using LS-DYNA, as well as fundamental theoretical concepts.Item Estimation of beam prestress by deflection and strain measurements(2012-08) An, JinWoo; Tassoulas, John Lambros; Manuel, LanceLaboratory test of reinforced and prestressed concrete structures have been used widely to explore the behavior of reinforced and prestressed concrete components and structures; Such tests are often time-consuming and costly. However, numerical models have been shown to compare favorably with experiments. Thus, computations are viewed nowadays as efficient alternatives to tests, time-wise and cost-wise. In the research reported in this thesis, finite-element model were used in a study of pretressed structural components in order to correlate levels of pretension with deflection and strain measurements. The two main objectives were to develop a suitable finite element model of prestressed concrete beams and to forecast beam prestension on the basis of deformations resulting from specified simple load, e.g., a uniformly distributed transverse load. A commercial finite-element analysis package (ANSYS 12) was used to set up, use and evaluate the computational model. Furthermore, a finite-difference model was employed in order to ascertain the validity of ANSYS results by comparison with engineering beam theory taking into account the applied pretension. This study demonstrates the potential usefulness of deflection and strain measurements as indicators of the pretension applied or remaining in prestressed concrete beams.Item Experimental and Numerical Studies of Aluminum-Alumina Composites(2013-07-22) Gudlur, PradeepThe preliminary goal of this study is to determine the effects of processing conditions, compositions and microstructural morphologies of the constituents on the physical and thermo-mechanical properties of alumina (Al_2O_3) reinforced aluminum (Al) composites. Composites with 0, 5, 10, 20 and 25 vol% Al_2O_3 were manufactured using powder metallurgy method. The elastic properties (Young's and shear modulus) and the coefficient of thermal expansion (CTE) of the composites were determined using Resonant Ultrasound Spectroscopy (RUS) and Thermo Mechanical Analyzer (TMA) respectively at various temperatures. Increasing compacting pressure improved relative density (or lowered porosity) of the composites. Furthermore, increasing the Al_2O_3 vol% in the composite increased the elastic moduli and reduced the CTE of the composites. Increasing the testing temperature from 25 to 450 oC, significantly reduced the elastic moduli of the composites, while the CTE of the composites changed only slightly with temperatures. Secondly, the goal of this study is to determine the effect of microstructures on the effective thermo-mechanical properties of the manufactured Al-Al_2O_3 composites using finite element (FE) method. Software OOF was used to convert the SEM micrographs of the manufactured composites to FE meshed models, which were then used to determine the effective elastic modulus and CTE. It was observed that, effective modulus dropped by 19.7% when porosity increased by 2.3%; while the effective CTE was mildly affected by the porosity. Additionally, the effect of residual stress on the effective thermo-mechanical properties was studied, and the stress free temperature of the composites was determined. Another objective of this study is to examine the stress-strain response of Al-Al_2O_3 composites due to compressive loads at various temperatures. Elastic modulus, yield stress and strain hardening parameters were determined from the stress-strain curves and their dependency on temperature, porosity and volume fraction were studied. The experimental results were compared with the numerical results. It was observed that high-localized stresses were present near the pores and at the interfaces between Al and Al_2O_3 constituents. Finally, functionally graded materials (FGMs) with varying Al_2O_3 concentration (0, 5and 10 vol%) in Al were manufactured; and their stress-strain response and CTE were determined at various temperatures.Item Extreme energy absorption : the design, modeling, and testing of negative stiffness metamaterial inclusions(2013-08) Klatt, Timothy Daniel; Seepersad, Carolyn C.; Haberman, Michael R.A persistent challenge in the design of composite materials is the ability to fabricate materials that simultaneously display high stiffness and high loss factors for the creation of structural elements capable of passively suppressing vibro-acoustic energy. Relevant recent research has shown that it is possible to produce composite materials whose macroscopic mechanical stiffness and loss properties surpass those of conventional composites through the addition of trace amounts of materials displaying negative stiffness (NS) induced by phase transformation [R. S. Lakes, et al., Nature, 410, pp. 565-567, (2001)]. The present work investigates the ability to elicit NS behavior without employing physical phenomena such as inherent nonlinear material behavior (e.g., phase change or plastic deformation) or dynamic effects, but rather the controlled buckling of small-scale structural elements, metamaterials, embedded in a continuous viscoelastic matrix. To illustrate the effect of these buckled elements, a nonlinear hierarchical multiscale material model is derived which estimates the macroscopic stiffness and loss of a composite material containing pre-strained microscale structured inclusions. The nonlinear multiscale model is then utilized in a set-based hierarchical design approach to explore the design space over a wide range of inclusion geometries. Finally, prototype NS inclusions are fabricated using an additive manufacturing technique and tested to determine quasi-static inclusion stiffness which is compared with analytical predictions.Item Finite Element Analysis of Ballistic Penetration of Plain Weave Twaron CT709? Fabrics: A Parametric Study(2011-10-21) Gogineni, SireeshaThe ballistic impact of Twaron CT709? plain weave fabrics is studied using an explicit finite element method. Many existing approximations pertaining to woven fabrics cannot adequately represent strain rate-dependent behavior exhibited by the Twaron fabrics. One-dimensional models based on linear viscoelasticity can account for rate dependency but are limited by the simplifying assumptions on the fabric architecture and stress state. In the current study, a three-dimensional fabric model is developed by treating each individual yarn as a continuum. The yarn behavior is phenomenologically described using a three-dimensional linear viscoelastic constitutive relation. A user subroutine VUMAT for ABAQUS/Explicit? is developed to incorporate the constitutive behavior. By using the newly developed viscoelasticity model, a parametric study is carried out to analyze the effects of various parameters on the impact behavior of the Twaron fabrics, which include projectile shape and mass, gripping conditions, inter-yarn friction, and the number of fabric layers. The study leads to the determination of the optimal number of fabric layers and the optimized level of inter-yarn friction that are needed to achieve the maximum energy absorption at specified impact speeds. The present study successfully utilizes the combination of 3D weave architecture and the strain rate dependent material behavior. Majority of the existing work is based either on geometry simplification or assumption of elastic material behavior. Another significant advantage with the present approach is that the mechanical constitutive relation, coded in FORTRAN?, is universal in application. The desired material behavior can be obtained by just varying the material constants in the code. This allows for the extension of this work to any fabric material which exhibits a strain-rate dependent behavior in addition to Twaron?. The results pertaining to optimal number of fabric layers and inter-yarn friction levels can aid in the manufacturing of fabric with regard to the desired level of lubrication/additives to improve the fabric performance under impact.Item Finite element analysis of doubler plate attachment details and load paths in continuity plates for steel moment frames(2012-05) Donkada, Shravya; Engelhardt, Michael D.; Helwig, ToddThis thesis presents results of research aimed at developing an improved understanding of the behavior of column panel zones reinforced with doubler plates in seismic resistant steel moment frames. A primary goal of the research was to develop data to support the development of improved design guidelines for welding doubler plates to columns, with and without the presence of continuity plates. The research addressed several issues and questions related to welding and detailing of doubler plates. This included evaluation of the effects of welding the top and bottom of the doubler plate in addition to the vertical edges, the effects of extending the doubler plate beyond the panel zone, and the impact of welding a continuity plate to a doubler plate. These issues were investigated through detailed finite element models of a simplified representation of the panel zone region, subjected to monotonic loading. The results of the research suggest that, in general, there is little benefit in welding the top and bottom edges of a doubler plate if the vertical edges are welded, particularly in terms of overall panel zone strength and stiffness. However, the top and bottom welds provide some benefit in reducing stresses on the vertical welds. The results also suggest that extending the doubler plate above and below the panel zone has little benefit for heavy columns of shallow depth, such as the W14x398 considered in this analysis. However, extending the doubler plate did result in approximately a 10-percent increase in panel zone strength for deeper columns, such as the W40x264 considered in this analysis. Finally, the results showed that welding a continuity plate directly to a doubler plate had no adverse effects on the doubler plate in terms of increased forces or stresses. Interestingly, welding the continuity plate to the doubler plate simply changed the load path for transfer of load from the beam flange to the column web and doubler plate, but did not change the stresses in the doubler plate. Further research is needed to validate these findings for more accurate representations of the panel zone region of the column and for cyclic loading.Item Finite element analysis of steel moment frame joints with doubler plates and continuity plates(2016-08) Cheng, Yu-Fang, M.S. in Engineering; Engelhardt, Michael D.; Helwig, Todd AThis thesis presents the results of a finite element study of the behavior of the panel zone region in beam-column joints in seismic resistant steel moment frames, with a focus on the interaction between continuity plates and extended doubler plates. Several recent studies have examined this same issue, but utilized a simplified finite element model of the panel zone region that did not include a complete representation of the beams attached to the column.. The previous studies concluded that welding a continuity plate to a doubler plate produced no apparent detrimental effects in the doubler plate. However, there is still a question on whether welding a continuity plate to a thin doubler plate may have a detrimental effect on the beam flanges, as the doubler plate may negatively impact the effectiveness of the continuity plate in reducing stress and strain concentrations in the beam flanges. As an extension to these previous research, the primary goal of this research was to examine the conclusions of these previous studies and to determine if any these previous conclusions might be altered once the entire beam and beam-to-column connection is included in the model. The research involved parametric finite element studies that included a full and very detailed representation of the beam and beam-to-column connection, using a welded unreinforced flange – welded web (WUF-W) connection The development and validation of modeling techniques used for this research is described, along with the results of the extensive series of parametric studies. The results suggest that welding continuity plates to thin doubler plate, as thin as 3/16-inch, does not significantly reduce the effectiveness of the continuity plates, in terms of controlling stress and strain concentrations in the beam flange. This study on full beam-column subassemblies showed essentially the same conclusion as that reported by previous studies.Item Finite element analysis of wood shoring towers used in Urban Search and Rescue(2012-12) Blair, Robert Stevenson; Wheat, Dan L.; Engelhardt, Michael DThis thesis focuses on the finite element modeling and analysis of wood shoring towers used by Urban Search and Rescue (US&R) teams during emergency response situations. These shores are constructed on site to provide temporary stabilization to a damaged structure. A high demand exists for experimental testing of the performance of these shores under non-ideal loading conditions, and for possible design modifications that could improve their overall behavior. To respond to this need, a total of thirteen vertical shores of the type laced post (LP) and plywood laced post (PLP) were constructed and tested at the Ferguson Structural Engineering Laboratory (FSEL) in Austin, Texas. The tests conducted on these shores aimed to investigate their performance under purely vertical load as well as various combinations of vertical and lateral loads. Finite element models for eight of the shores tested at FSEL were built and analyzed in Abaqus to compare the computed results with the actual linear elastic response of the shores. Material properties for the posts in each shore were obtained through further material testing at the conclusion of each shore test. Shore members were assumed to be isotropic. Solid elements were used to model each member, and Cartesian connector elements with a predefined nonlinear stiffness were used to model each nail. In general, the vertical load-displacement response computed from Abaqus exhibited good agreement with the laboratory results for the linear elastic range. The same general modeling scheme was then used to make design changes to the original shores based on observations gained during testing as well as modeling. Each design change was modeled, analyzed, and then compared with the computed results from the original shore design as well as the other design changes. The basis for evaluating the effectiveness of a given shore design involved comparing the bending moment diagrams for each post and the maximum first story nail slips (connector displacements). Recommendations were made for improved shore designs to be verified by experimental testing.Item Mathematical modeling of evaporative cooling of moisture bearing epoxy composite plates(Texas A&M University, 2006-08-16) Payette, Gregory StevenResearch is performed to assess the potential of surface moisture evaporative cooling from composite plates as a means of reducing the external temperature of military aircraft. To assess the feasibility of evaporative cooling for this application, a simplified theoretical model of the phenomenon is formulated. The model consists of a flat composite plate at an initial uniform temperature, T0. The plate also possesses an initial moisture (molecular water) content, M0. The plate is oriented vertically and at t=0 s, one surface is exposed to a free stream of air at an elevated temperature. The other surface is exposed to stagnant air at the same temperature as the plate??s initial temperature. The equations associated with energy and mass transport for the model are developed from the conservation laws per the continuum mechanics hypothesis. Constitutive equations and assumptions are introduced to express the two nonlinear partial differential equations in terms of the temperature, T, and the partial density of molecular water, ρw. These equations are approximated using a weak form Galerkin finite element formulation and the α??family of time approximation. An algorithm and accompanying computer program written in the Matlab programming language are presented for solving the nonlinear algebraic equations at successive time steps. The Matlab program is used to generate results for plates possessing a variety of initial moisture concentrations, M0, and diffusion coefficients, D. Surface temperature profiles, over time, of moisture bearing specimens are compared with the temperature profiles of dry composite plates. It is evident from the results that M0 and D affect the surface temperature of a moist plate. Surface temperature profiles are shown to decrease with increasing M0 and/or D. In particular, dry and moist specimens are shown to differ in final temperatures by as much as 30??C over a 900 s interval when M0 = 30% and D is on the order of 10??8m2/s (T0 = 25??C, h = 60 W/m2??C, T∞ = 90??C).Item On a tensor-based finite element model for the analysis of shell structures(Texas A&M University, 2006-04-12) Arciniega Aleman, Roman AugustoIn the present study, we propose a computational model for the linear and nonlinear analysis of shell structures. We consider a tensor-based finite element formulation which describes the mathematical shell model in a natural and simple way by using curvilinear coordinates. To avoid membrane and shear locking we develop a family of high-order elements with Lagrangian interpolations. The approach is first applied to linear deformations based on a novel and consistent third-order shear deformation shell theory for bending of composite shells. No simplification other than the assumption of linear elastic material is made in the computation of stress resultants and material stiffness coefficients. They are integrated numerically without any approximation in the shifter. Therefore, the formulation is valid for thin and thick shells. A conforming high-order element was derived with 0 C continuity across the element boundaries. Next, we extend the formulation for the geometrically nonlinear analysis of multilayered composites and functionally graded shells. Again, Lagrangian elements with high-order interpolation polynomials are employed. The flexibility of these elements mitigates any locking problems. A first-order shell theory with seven parameters is derived with exact nonlinear deformations and under the framework of the Lagrangian description. This approach takes into account thickness changes and, therefore, 3D constitutive equations are utilized. Finally, extensive numerical simulations and comparisons of the present results with those found in the literature for typical benchmark problems involving isotropic and laminated composites, as well as functionally graded shells, are found to be excellent and show the validity of the developed finite element model. Moreover, the simplicity of this approach makes it attractive for future applications in different topics of research, such as contact mechanics, damage propagation and viscoelastic behavior of shells.Item Performance of suction caissons with a small aspect ratio(2013-12) Chen, Ching-Hsiang, active 2013; Gilbert, Robert B. (Robert Bruce), 1965-Suction caissons with a smaller aspect (length to diameter) ratio are increasingly used for supporting offshore structures, such as wind turbines and oil and gas production facilities. The design of these stubbier foundations is usually governed by lateral loads from wind, waves, or currents. It is desired to have more physical understanding of the behavior of less slender suction caissons under cyclic lateral loading condition and to have robust design tools for analyzing these laterally loaded caissons. In this study, one-g model tests with 1:25 and 1:50 suction can foundation scale models with an aspect ratio of one are conducted in five different soil profiles: normally consolidated clay, overconsolidated clay, loose siliceous sand, cemented siliceous sand, and cemented calcareous sand. This test program involves monitoring settlements, lateral displacements (walking), tilt, lateral load and pore water pressures in the suction can during two-way cyclic lateral loading at one, three and five degrees of rotation. The model foundations are monitored during installation, axial load tests, and pullout tests. In one and two-degree (±0.5 and ±1 degree) rotation tests, the suction can does not have significant walking or settlement in all the five soil profiles after 1000 load cycles. However, more significant walking or settlement may occur at extreme conditions such as the 5-degree (±2.5 degrees) rotation tests. Gaps between the foundation wall and the soil may also form in these extreme conditions in overconsolidated clay, cemented siliceous sand, and cemented calcareous sand. Plastic limit analysis, finite element analysis, and finite difference analysis are used to evaluate the laterally loaded suction can in clay. The plastic limit analysis originally developed for more slender suction caissons appears to predict a lateral capacity close to the measured short-term static capacity of the caisson with an aspect ratio of one when undisturbed undrained shear strength of soil is used. However, this plastic limit model underestimates the long-term cyclic lateral load capacity of the caisson when the remolded undrained shear strength was used. The finite element model developed in this study can simulate the development and effect of a gap between the foundation and surrounding soil as observed in the experiments in overconsolidated clay. The lateral load-displacement response predicted by this finite element model matches well with the experimental data. Finally, finite difference analysis for a rigid caisson with lateral and rotational springs was developed by fitting the lateral load-displacement response of the suction can in clay. The calibrated p-y curves for rigid caisson are significantly stiffer and have higher ultimate resistance than the p-y curves recommended by API which is consistent with other studies. This finite difference model provides an efficient approach to analyze a laterally loaded caisson with a small aspect ratio in clay.Item Predicting the behavior of horizontally curved I-girders during construction(2010-08) Stith, Jason Clarence; Williamson, Eric B., 1968-; Helwig, Todd Aaron, 1965-; Frank, Karl H.; Engelhardt, Michael D.; Liechti, Kenneth M.The majority of a bridge designer’s time is spent ensuring strength and serviceability limit states are satisfied for the completed structure under various dead and live loads. Anecdotally, the profession has done an admirable job designing safe bridges, but engineering the construction process by which bridges get built plays a lesser role in the design offices. The result of this oversight is the complete collapse of a few large bridges as well as numerous other serviceability failures during construction. According to the available literature there have been only a few attempts to monitor a full-scale bridge in the field during the entire construction process. Another challenge for engineers is the lack of analysis tools available which predict the behavior of the bridge during the intermediate construction phases. During construction, partial bracing is present and the boundary conditions can vary significantly from the final bridge configuration. The challenge is magnified for complex bridge geometries such as curved bridges or bridges with skewed supports. To address some of the concerns facing engineers a three span curved steel I-girder bridge was monitored throughout the entire construction process. Field studies collected data on the girder lifting behavior, partially constructed behavior, and concrete deck placement behavior. Additional analytical studies followed using the field measurements to verify the finite element models. Finally, conclusions drawn from the physical and analytical testing were utilized to derive equations that predicted behavior, and analysis tools were developed to provide engineers with solutions to a wide range of construction related problems. This dissertation describes the development of two design tools, UT Lift and UT Bridge. UT Lift is a macro-enabled Excel spreadsheet that predicts the behavior of curved I-girders during lifting. The derivation of the equations necessary to accomplish these calculations and the implementation are described in this dissertation. UT Bridge is a PC-based, user-friendly, 3-D finite element program for I-girder bridges. The basic design philosophy of UT Bridge aims to allow an engineer to take the information readily available in a set of bridge drawings and easily input the necessary information into the program. A straight or curved I-girder bridge with any number of girders or spans can then be analyzed with a robust finite element analysis for either the erection sequence or the concrete deck placement. The development of UT Bridge as well as the necessary element formulations is provided in this dissertation.Item Structural optimization for a photovoltaic vehicle(2011-05) Ford, Bennett Alan 1984-; O'Connor, James ThomasPhotovoltaic vehicles are designed to harness solar energy and use it for self-propulsion. In order to collect sufficient energy to propel a passenger, a relatively large photovoltaic array is required. Controlling the loads imparted by the array and the body that supports it, while protecting the passenger and minimizing vehicle weight, presents a unique set of design challenges. Weight considerations and geometric constraints often lead system designers toward unconventional structural solutions. This report details analytical and experimental processes aimed at proving the concept of integrating aluminum space-frame elements with composite panels. Finite element analysis is used to simulate load conditions, and results are compared with empirical test data.