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Articles 1 - 12 of 12
Full-Text Articles in Applied Mechanics
Load Path Uncertainty In A Wood Structure And The Effect On Structural Reliability, Wenqi Wang, Christopher D. Eamon
Load Path Uncertainty In A Wood Structure And The Effect On Structural Reliability, Wenqi Wang, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
The roof truss bearing points of a light-framed wood house were instrumented with load cells. It was found that under dead load alone, symmetric and theoretically identical truss reactions have significant variation. A similar degree of reaction discrepancy was found under the application of uplift pressures caused by hurricane winds. Analysis revealed that the majority of this discrepancy is caused by inherent uncertainties in load path. Although uncertainties in load magnitude and material resistance are accounted for in design by use of appropriate load and resistance factors, load path is generally taken to be deterministic. In this study, load path …
Reliability Analysis Of Reinforced Concrete Columns Exposed To Fire, Christopher D. Eamon, Elin A. Jensen
Reliability Analysis Of Reinforced Concrete Columns Exposed To Fire, Christopher D. Eamon, Elin A. Jensen
Civil and Environmental Engineering Faculty Research Publications
A reliability analysis is conducted on reinforced concrete columns subjected to fire load. From an evaluation of load frequency of occurrence, load random variables are taken to be dead load, sustained live load, and fire temperature. Resistance is developed for axial capacity, with random variables taken as steel yield strength, concrete compressive strength, placement of reinforcement, and section width and height. A rational interaction model based on the Rankine approach is used to estimate column capacity as a function of fire exposure time. Various factors were considered in the analysis such as fire type, load ratio, reinforcement ratio, cover, concrete …
Reliability-Based Design Optimization Of Concrete Flexural Members Reinforced With Ductile Frp Bars, Bashar Behnam, Christopher D. Eamon
Reliability-Based Design Optimization Of Concrete Flexural Members Reinforced With Ductile Frp Bars, Bashar Behnam, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
In recent years, ductile hybrid FRP (DHFRP) bars have been developed for use as tensile reinforcement. However, initial material costs regain high, and it is difficult to simultaneously meet strength, stiffness, ductility, and reliability demands. In this study, a reliability-based design optimization (RBDO) is conducted to determine minimum cost DHFRP bar configurations while enforcing essential constraints. Applications for bridge decks and building beams are considered, with 2, 3, and 4-material bars. It was found that optimal bar configuration has little variation for the different applications, and that overall optimized bar cost decreased as the number of bar materials increased.
Reliability Analysis Of Rc Beams Exposed To Fire, Christopher D. Eamon, Elin A. Jensen
Reliability Analysis Of Rc Beams Exposed To Fire, Christopher D. Eamon, Elin A. Jensen
Civil and Environmental Engineering Faculty Research Publications
A procedure for conducting reliability analysis of reinforced concrete beams subjected to a fire load is presented. This involves identifying relevant load combinations, specifying critical load and resistance random variables, and establishing a high-temperature performance model for beam capacity. Based on the procedure, an initial reliability analysis is conducted using currently available data. Significant load random variables are taken to be dead load, sustained live load, and fire temperature. Resistance is in terms of moment capacity, with random variables taken as steel yield strength, concrete compressive strength, placement of reinforcement, beam width, and thermal diffusivity. A semi-empirical model is used …
Life-Cycle Cost Analysis Of Alternative Reinforcement Materials For Bridge Superstructures Considering Cost And Maintenance Uncertainties, Christopher D. Eamon, Elin A. Jensen, Nabil F. Grace, Xiuwei Shi
Life-Cycle Cost Analysis Of Alternative Reinforcement Materials For Bridge Superstructures Considering Cost And Maintenance Uncertainties, Christopher D. Eamon, Elin A. Jensen, Nabil F. Grace, Xiuwei Shi
Civil and Environmental Engineering Faculty Research Publications
A life cycle cost analysis (LCCA) was conducted on prestressed concrete bridges using carbon fiber reinforced polymer (CFRP) bars and strands. Traditional reinforcement materials of uncoated steel with cathodic protection and epoxy-coated steel were also considered for comparison. A series of deterministic LCCAs were first conducted to identify a range of expected cost outcomes for different bridge spans and traffic volumes. Then, a probabilistic LCCA was conducted on selected structures that included activity timing and cost random variables. It was found that although more expensive initially, the use of CFRP reinforcement has the potential to achieve significant reductions in life …
Reliability Estimation Of Complex Numerical Problems Using Modified Conditional Expectation Method, Christopher D. Eamon, Bulakorn Charumas
Reliability Estimation Of Complex Numerical Problems Using Modified Conditional Expectation Method, Christopher D. Eamon, Bulakorn Charumas
Civil and Environmental Engineering Faculty Research Publications
A simulation-based structural reliability analysis method is presented. It is intended as an alternate approach to estimate reliability for problems for which most-probable point of failure methods fail and when computational resources are limited. The proposed method combines conditional expectation and estimating the PDF or CDF of a selected portion of the limit state. In the proposed approach, complex limit state functions are simplified to two random variable problems. The success of the simplification depends on the quality of the CDF estimate. Results indicate that the method may provide accurate and efficient solutions for some difficult reliability problems.
Integrated Reliability And Sizing Optimization Of A Large Composite Structure, Christopher D. Eamon, Masoud Rais-Rohani
Integrated Reliability And Sizing Optimization Of A Large Composite Structure, Christopher D. Eamon, Masoud Rais-Rohani
Civil and Environmental Engineering Faculty Research Publications
In this paper, we present the application of probabilistic design modeling and reliability-based design optimization (RBDO) methodology to the sizing optimization of a composite advanced submarine sail structure under parametric uncertainty. With the help of probabilistic sensitivity analysis, the influence of individual random variables on each structural failure mode is examined, and the critical modes are treated as probabilistic design constraints under consistent lower bounds on the corresponding reliability indices. Whereas the failure modes are applied to structural components in the solution of the RBDO problem, the overall system reliability is also evaluated as a post-optimization step. The results indicate …
Reliability Of Concrete Masonry Unit Walls Subjected To Explosive Loads, Christopher D. Eamon
Reliability Of Concrete Masonry Unit Walls Subjected To Explosive Loads, Christopher D. Eamon
Civil and Environmental Engineering Faculty Research Publications
This study discuses the development of a procedure that can be used to assess the reliability of concrete masonry unit infill walls subjected to personnel-delivered blast loads. Consideration is given to maintain reasonable computational effort for both the structural analysis and reliability models. Blast load and wall resistance models are developed based on experimental and analytical data, and resistance is evaluated with a large strain, large displacement transient dynamic finite element analysis. A sensitivity analysis is conducted to identify significant random variables and a reliability analysis conducted with a feasible level of computational effort. Reliability indices are estimated for two …
Reliability-Based Optimization Of Fiber-Reinforced Polymer Composite Bridge Deck Panels, Michel D. Thompson, Christopher D. Eamon, Masoud Rais-Rohani
Reliability-Based Optimization Of Fiber-Reinforced Polymer Composite Bridge Deck Panels, Michel D. Thompson, Christopher D. Eamon, Masoud Rais-Rohani
Civil and Environmental Engineering Faculty Research Publications
A reliability-based optimization (RBO) procedure is developed and applied to minimize the weight of eight fiber-reinforced polymer composite bridge deck panel configurations. The method utilizes interlinked finite element, optimization, and reliability analysis procedures to solve the weight minimization problem with a deterministic strength constraint and two probabilistic deflection constraints. Panels are composed of an upper face plate, lower face plate, and a grid of interior stiffeners. Different panel depths and stiffener layouts are considered. Sensitivity analyses are conducted to identify significant design and random variables. Optimization design variables are panel component ply thicknesses while random variables include load and material …
Evaluation Of Accuracy And Efficiency Of Some Simulation And Sampling Methods In Structural Reliability Analysis, Christopher D. Eamon, Michel D. Thompson, Zhenyu Liu
Evaluation Of Accuracy And Efficiency Of Some Simulation And Sampling Methods In Structural Reliability Analysis, Christopher D. Eamon, Michel D. Thompson, Zhenyu Liu
Civil and Environmental Engineering Faculty Research Publications
Numerous simulation and sampling methods can be used to estimate reliability index or failure probability. Some point sampling methods require only a fraction of the computational effort of direct simulation methods. For many of these methods, however, it is not clear what trade-offs in terms of accuracy, precision, and computational effort can be expected, nor for which types of functions they are most suited. This study uses nine procedures to estimate failure probability and reliability index of approximately 200 limit state functions with characteristics common in structural reliability problems. The effects of function linearity, type of random variable distribution, variance, …
Effect Of Edge-Stiffening And Diaphragms On The Reliability Of Bridge Girders, Christopher D. Eamon, Andrzej S. Nowak
Effect Of Edge-Stiffening And Diaphragms On The Reliability Of Bridge Girders, Christopher D. Eamon, Andrzej S. Nowak
Civil and Environmental Engineering Faculty Research Publications
Secondary elements such as barriers, sidewalks, and diaphragms may affect the distribution of live load to bridge girders. The objective of this study is to evaluate their effect on girder reliability if these elements are designed to be sufficiently attached to the bridge so as not to detach under traffic live loads. Simple span, two lane structures are considered, with composite steel girders supporting a reinforced concrete deck. Several representative structures are selected, with various configurations of barriers, sidewalks and diaphragms. Bridge analysis is performed using a finite element procedure. Load and resistance parameters are treated as random variables. Random …
Modeling Concrete Masonry Walls Subjected To Explosive Loads, Christopher D. Eamon, James T. Baylot, James L. O'Daniel
Modeling Concrete Masonry Walls Subjected To Explosive Loads, Christopher D. Eamon, James T. Baylot, James L. O'Daniel
Civil and Environmental Engineering Faculty Research Publications
Concrete masonry unit walls subjected to blast pressure were analyzed with the finite element method, with the goal of developing a computationally-efficient and accurate model. Wall behavior can be grouped into three modes of failure, which correspond to three ranges of blast pressures. Computational results were compared to high-speed video images and debris velocities obtained from experimental data. A parametric analysis was conducted to determine the sensitivity of computed results to critical modeling values. It was found that the model has the ability to replicate experimental results with good agreement. However, it was also found that, without knowledge of actual …