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Detection Of 4-Point Bend Induced Micro-Cracks In Cfrp Laminates Via Coda Wave Nde, Richard Livings, Dan Barnard, Vinay Dayal 2017 Iowa State University

Detection Of 4-Point Bend Induced Micro-Cracks In Cfrp Laminates Via Coda Wave Nde, Richard Livings, Dan Barnard, Vinay Dayal

Vinay Dayal

Although coda wave NDE has been shown to have some sensitivity to realistic damage in concrete structures, the technique’s capability for detecting micro-cracks in fibrous composite materials has yet to be evaluated. This paper reports on the first investigation of realistic damage, specifically micro-cracks, in fibrous composite materials using coda wave differential signal features. Micro-cracks were generated in CFRP samples using the 4-point bending configuration shown in Fig. 1. The damage was monitored during loading with Acoustic Emission, and the loading was stopped after each significant damage event. The damage was then examined with coda wave NDE, immersion UT ...


Structural Behavior Of Inflatable, Reinforced, Braided, Tubular Members, Joshua Clapp 2017 University of Maine

Structural Behavior Of Inflatable, Reinforced, Braided, Tubular Members, Joshua Clapp

Electronic Theses and Dissertations

The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) system being developed by the National Aeronautics and Space Administration (NASA) is an inflatable structure composed of multiple, concentric, pressurized tori, load straps, and a thermal protection system. The HIAD overcomes limitations inherent with the use of rigid decelerators since the deployed diameter is much larger than the packed size, which makes it an enabling technology for new opportunities in space exploration. The HIAD is designed to decelerate and protect spacecraft during atmospheric re-entry. The objective of this research was to improve understanding of structural behavior of HIAD components through material testing, structural testing ...


On The Ramberg-Osgood Stress-Strain Model And Large Deformations Of Cantilever Beams, Ronald J. Giardina Jr 2017 University of New Orleans

On The Ramberg-Osgood Stress-Strain Model And Large Deformations Of Cantilever Beams, Ronald J. Giardina Jr

University of New Orleans Theses and Dissertations

In this thesis the Ramberg-Osgood nonlinear model for describing the behavior of many different materials is investigated. A brief overview of the model as it is currently used in the literature is undertaken and several misunderstandings and possible pitfalls in its application is pointed out, especially as it pertains to more recent approaches to finding solutions involving the model. There is an investigation of the displacement of a cantilever beam under a combined loading consisting of a distributed load across the entire length of the beam and a point load at its end and new solutions to this problem are ...


Performance Of Mud Mortar Walls Under Seismic Loading, Christian L. Berneking VI, Santiago Pujol, Prateek Pratap Shah, Lucas Laughery 2017 Purdue University

Performance Of Mud Mortar Walls Under Seismic Loading, Christian L. Berneking Vi, Santiago Pujol, Prateek Pratap Shah, Lucas Laughery

The Summer Undergraduate Research Fellowship (SURF) Symposium

The inherently brittle nature of unreinforced masonry structures results in poor performance during earthquakes, presenting major hazards to communities. Many of these structures found in Nepal were severely damaged or destroyed during two earthquakes in 2015. The purpose of this project is to test the effect on seismic response of several modifications to stone and mud mortar structures. These structures are common in many areas of Nepal. Two T-shaped stone and mud mortar masonry walls are constructed. The first wall has no modifications and represents current building practices. The second wall uses steel wire mesh as external reinforcement. Each wall ...


The Effect Of Reinforcing Bar Bend Radius On The Strength And Behavior Of Knee Joints, Xitong Zhou, Christopher S. Williams, Hwa Ching Wang 2017 Purdue University

The Effect Of Reinforcing Bar Bend Radius On The Strength And Behavior Of Knee Joints, Xitong Zhou, Christopher S. Williams, Hwa Ching Wang

The Summer Undergraduate Research Fellowship (SURF) Symposium

The strut-and-tie method (STM) is used by structural engineers to design discontinuity regions of reinforced concrete structures. Using STM, the stress distribution in a concrete member is expressed as a set of struts, ties, and nodes in a strut-and-tie model. These components are then proportioned and evaluated to develop an appropriate design. One type of node that appears in knee joints (i.e., frame corners) subjected to closing moments is referred to as a curved-bar node. Although curved-bar nodes represent a unique concentration of stresses in a structure, little research focused on curved-bar node design has been conducted. In response ...


Buckling Of Cylindrical Shells Under Wind Loading, Tianlong Sun, Eyas Azzuni, Sukru Guzey 2017 Purdue University

Buckling Of Cylindrical Shells Under Wind Loading, Tianlong Sun, Eyas Azzuni, Sukru Guzey

The Summer Undergraduate Research Fellowship (SURF) Symposium

Cylindrical shells such as aboveground steel storage tanks are widely used to store gases, chemicals and fuels. Stiffener rings are introduced to prevent cylindrical shells from buckling due to wind loads. The current top wind stiffener design rules used in the USA for such cylindrical storage tanks are specified in API 650. However, the design methodology of top stiffener rings is overly conservative. Therefore, relaxation of the design rules for the top stiffener is investigated in this study. The API 650 mandated top stiffener size was reduced to the same size as the mandated intermediate stiffener ring in this study ...


Post-Earthquake Fire Assessment Of Steel Buildings, Yi Li, Rachel Chicchi, Amit H. Varma 2017 Purdue University

Post-Earthquake Fire Assessment Of Steel Buildings, Yi Li, Rachel Chicchi, Amit H. Varma

The Summer Undergraduate Research Fellowship (SURF) Symposium

Resilience of structural systems after hazardous events is a crucial concern of building design. An abundance of research has focused on hazards such as seismic and fire separately. This project conducted a multi-hazard study on steel buildings considering both seismic and fire damage. A literature review of the behavior of steel-framed buildings due to fires after earthquakes, known as post-earthquake fires (PEF), is offered. The new PEF methodology, delivered in this study, starts with creating a three dimensional (3D) model of the examined steel building using the finite element method software, ABAQUS. Next, varying intensities of seismic and fire hazards ...


Hazard Assessment Of Meteoroid Impact For The Design Of Lunar Habitats, Herta Paola Montoya, Shirley Dyke, Julio A. Ramirez, Antonio Bobet, H. Jay Melosh, Daniel Gomez 2017 Purdue University

Hazard Assessment Of Meteoroid Impact For The Design Of Lunar Habitats, Herta Paola Montoya, Shirley Dyke, Julio A. Ramirez, Antonio Bobet, H. Jay Melosh, Daniel Gomez

The Summer Undergraduate Research Fellowship (SURF) Symposium

The design of self-sustaining lunar habitats is a challenge primarily due to the Moon’s lack of atmospheric protection and hazardous environment. To assure safe habitats that will lead to further lunar and space exploration, it is necessary to assess the different hazards faced on the Moon such as meteoroid impacts, extreme temperatures, and radiation. In particular, meteoroids pose a risk to lunar structures due to their high frequency of occurrence and hypervelocity impact. Continuous meteoroid impacts can harm structural elements and vital equipment compromising the well-being of lunar inhabitants. This study is focused on the hazard conceptualization and quantification ...


Large Payload Hiad Systems: Development Of Computationally Efficient Modeling Strategies And Structural Investigations, Andrew C. Young 2017 University of Maine

Large Payload Hiad Systems: Development Of Computationally Efficient Modeling Strategies And Structural Investigations, Andrew C. Young

Electronic Theses and Dissertations

The hypersonic inflatable aerodynamic decelerator (HIAD) system under development by the National Aeronautics and Space Administration (NASA) has the potential to deliver the size of payloads to the Martian surface that will be necessary for future human-scale missions. An important step in realizing the promise of the HIAD system is to understand the structural behavior of this inflatable, textile, relatively compliant system. This is accomplished through structural testing and the development of structural modeling and analysis methodologies and tools. The structural modeling tools that have been developed to date utilize a continuum, shell-based finite element (FE) analysis approach. This methodology ...


Soil-Structure Interaction Effects On The Seismic Response Of Low-Rise Eccentrically Braced Frames, Luis Gerardo Buitrago Goyez 2017 University of Arkansas, Fayetteville

Soil-Structure Interaction Effects On The Seismic Response Of Low-Rise Eccentrically Braced Frames, Luis Gerardo Buitrago Goyez

Theses and Dissertations

The importance of soil-structure interaction (SSI) effects on the seismic response of

buildings has been long recognized and has been researched for over 40 years. However, SSI

analysis has only been applied in a few building projects because the fixed base condition is

considered to provide a conservative estimation for the response of buildings under seismic loads.

This assumption of a fixed base condition adopted by practitioners is not always conservative or

cost-effective, especially for rigid buildings over soft soils. Additionally, for the case of ductile

steel frames with eccentric configurations, the influence of SSI on their seismic performance has ...


The Effect Of Microencapsulated Phase-Change Material On The Compressive Strength Of Structural Concrete, Chad Norvell, David J. Sailor, Peter Dusicka 2017 Portland State University

The Effect Of Microencapsulated Phase-Change Material On The Compressive Strength Of Structural Concrete, Chad Norvell, David J. Sailor, Peter Dusicka

Peter Dusicka

Latent heat energy storage through phase-change materials (PCMs) is one possible strategy to control interior temperatures in buildings, improve thermal comfort, and passively reduce building energy use associated with heating and cooling. While PCMs integrated into building structure elements have been studied since the 1970s, challenges of integrating PCMs into building materials while maintaining their heat storage benefits have limited their application in practice. The recent introduction of microencapsulated phase-change materials provides the energy storage capability of PCMs in micron-scale, chemically-inert capsules that can be easily integrated into composite materials such as gypsum wallboard and concrete. The size and physical ...


Seismic Retrofit Benefit Considering Statewide Transportation Assessment, Selamawit Tesfayesus Mehary, Peter Dusicka 2017 Portland State University

Seismic Retrofit Benefit Considering Statewide Transportation Assessment, Selamawit Tesfayesus Mehary, Peter Dusicka

Peter Dusicka

The purpose of this study was to identify and demonstrate a methodology to prioritize bridges for retrofit in the State of Oregon. Given the limited resources available, retrofitting all vulnerable bridges in the foreseeable future would not be practical. Instead, a retrofit strategy needs to be developed to prioritize the inventory and enumerate the retrofit cost. In this study, a prioritization methodology used a holistic assessment of overall roadway system to consider highway route segments, rather than individual bridges. The overall assessment was based on a cost-benefit analysis including retrofit cost, expected economic loss (with or without retrofit) and social ...


Seismic Vulnerability Of Oregon State Highway Bridges: Mitigation Strategies To Reduce Major Mobility Risks, Albert Nako, Craig Shike, Jan Six, Bruce Johnson, Peter Dusicka, Selamawit Tesfayesus Mehary 2017 Oregon Department of Transportation

Seismic Vulnerability Of Oregon State Highway Bridges: Mitigation Strategies To Reduce Major Mobility Risks, Albert Nako, Craig Shike, Jan Six, Bruce Johnson, Peter Dusicka, Selamawit Tesfayesus Mehary

Peter Dusicka

The Oregon Department of Transportation and Portland State University evaluated the seismic vulnerability of state highway bridges in western Oregon. The study used a computer program called REDARS2 that simulated the damage to bridges within a transportation network. It predicted ground motions for a specific location and magnitude of earthquake, resulting bridge damage and the cost of the damage, as well as the cost to the public for traffic delays due to detours around damaged bridges. Estimated damage and delay costs were presented for major highways in the region.


Testing And Strengthening Bridge Connections, Christopher Higgins, Peter Dusicka, Michael Scott 2017 Oregon State University

Testing And Strengthening Bridge Connections, Christopher Higgins, Peter Dusicka, Michael Scott

Peter Dusicka

Researchers evaluate and improve the strength of gusset plate connections, essential pieces in bridge design that can fail due to buckling.


Seismic Hazard Assessment Of Oregon Highway Truck Routes, Peter Dusicka, Selamawit Tesfayesus Mehary 2017 Portland State University

Seismic Hazard Assessment Of Oregon Highway Truck Routes, Peter Dusicka, Selamawit Tesfayesus Mehary

Peter Dusicka

This research project developed a seismic risk assessment model along the major truck routes in Oregon. The study had adopted federally developed software tools called Risk for Earthquake Damage to Roadway Systems (REDARS2) and HAZUS-MH. The model was the first time REDARS2 has been adopted and used in research outside of the original development team, presenting a number of unique challenges. The development of the model was a complex, intensive process that required a significant research effort, manipulation and adjustment of data. Furthermore, limitations of the software tools themselves had been identified that prevented the inclusion of important aspects such ...


Strength And Fatigue Of Three Glass Fiber Reinforced Composite Bridge Decks With Mechanical Deck To Stringer Connections, Andrew Gleason, Peter Dusicka 2017 Portland State University

Strength And Fatigue Of Three Glass Fiber Reinforced Composite Bridge Decks With Mechanical Deck To Stringer Connections, Andrew Gleason, Peter Dusicka

Peter Dusicka

Replacement of the steel grating deck on the lift span of the Morrison Bridge in Portland, OR, will utilize glass fiber reinforced polymer (FRP) panels to address ongoing maintenance issues of the deteriorated existing deck, improve driver safety and introduce bridge water runoff treatment. This report outlines the testing methods and results of an experimental program aimed primarily at evaluating a new open cell deck. While most FRP panels are connected via shear studs that are grouted within isolated pockets, the panels in this case were bolted directly to the steel stringers. Two different FRP deck options were evaluated for ...


Research Project Work Plan For Impact Of Cascadia Subduction Zone Earthquake On The Seismic Evaluation Criteria Of Bridges, Peter Dusicka 2017 Portland State University

Research Project Work Plan For Impact Of Cascadia Subduction Zone Earthquake On The Seismic Evaluation Criteria Of Bridges, Peter Dusicka

Peter Dusicka

The goal of this project is to provide ODOT with the best rational estimate of ground acceleration values for designing new and retrofitting existing bridges. The objectives are to: evaluate the hazard by contrasting the acceleration values from individual CSZ events to PSHA values provide experimental evidence of damage difference under longer duration shaking expected from CSZ event


Protecting Bridges From Earthquake Damage, Peter Dusicka 2017 Portland State University

Protecting Bridges From Earthquake Damage, Peter Dusicka

Peter Dusicka

Earthquake damage to bridges can have serious effects on a transportation network. When a bridge is out, the damage can go well beyond what is immediately visible: in addition to the cost of repairing it, the state must deal with short-term and long-term interruptions to traffic. These interruptions can delay repair and construction, as well as impacting post earthquake emergency response and causing the loss of valuable time for commuters and freight. To prevent this situation, older bridges (ones that are past an average construction life of about 50 years) should be retrofitted with stronger materials, especially in earthquake- prone ...


Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes, Peter Dusicka, Ramiro Bazaez, Sarah Knoles 2017 Portland State University

Bridge Seismic Retrofit Measures Considering Subduction Zone Earthquakes, Peter Dusicka, Ramiro Bazaez, Sarah Knoles

Peter Dusicka

Over the years, earthquakes have exposed the vulnerability of reinforced concrete structures under seismic loads. The recent occurrence of highly devastating earthquakes near instrumented regions, e.g. 2010 Maule, Chile and 2011 Tohoku, Japan, has demonstrated the catastrophic impact of such natural force upon reinforced concrete structures. Research was conducted to investigate the effect of subduction zone earthquakes on structural damage. The study suggests that large magnitude ground motions of long duration have the potential of significantly increasing the number of inelastic excursions and consequently incur more extensive structural damage as compared to ground motions with similar elastic spectral demands ...


Characterization Of Unknown Bridge Foundations, Saman Rashidyan 2017 University of New Mexico

Characterization Of Unknown Bridge Foundations, Saman Rashidyan

Civil Engineering ETDs

The National Bridge Inventory (NBI) recognized 86,133 bridges in the United States have no foundation data on record in 2003. It is evident that an unknown percentage of the 86,133 bridges identified by NBI with missing foundation data could also be highly vulnerable to scouring induced by water flow coupled with erodible soils. Conventional excavation, coring and boring excavations to identify unknown bridge foundation depths and types are deemed to be expensive, destructive, and limited in their application to the unknown foundation problem. Many surface and borehole nondestructive testing (NDT) technologies have been developed for this purpose. Three ...


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