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Automated Multi-Stage Triaxial Testing of Loose and Dense Sands

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The goal of this project was to develop criteria to signify when a soil specimen is just on the verge of failure when tested in a consolidated-drained triaxial test. By

The goal of this project was to develop criteria to signify when a soil specimen is just on the verge of failure when tested in a consolidated-drained triaxial test. By identifying the imminent failure of the specimen, a multi-stage triaxial test can be automated, allowing for soil strength properties to be determined from a single specimen. The purpose of identification of imminent failure of the specimen is for purposes of development of automated multi-stage test operation of a single specimen for determination of soil properties. Currently, shear strength parameters for a soil could either be calculated from at least three separate triaxial tests or a multi-stage test where each stage would end based on the operator's judgement. By developing generalized criteria that would signify failure, and therefore the need to move on to the next stage of a multi-state test, a computer program could be used to automatically end one loading stage and begin the next. This automation would allow for a wider use of multi-stage tests, which are faster and therefore less expensive to run than three standard triaxial tests. Triaxial tests were performed on loose and dense sand specimens. During standard testing, the loose sand had a friction angle of 29.61o and the dense sand had a friction angle of 38.63o. Using a zero tangent modulus as the stage-end criteria, the loose sand had a friction angle of 27.69o and the dense sand had a friction angle of 37.03o. Using the maximum volumetric strain as the stage-end criteria, the loose sand had a friction angle of 25.16o. The multi-stage shear strength parameters were reasonable compared to the single-stage test parameters, if slightly conservative. This suggests that computer automation of multi-stage triaxial tests will produce results that can be used in analysis and design by geotechnical engineers. However, more research will be required to confirm this initial assumptions for a wider range of sand gradations as well as for other soil types and testing conditions.

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Date Created
  • 2016-05

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THE STATE OF TRANSPORTATION INFRASTRUCTURE

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America's infrastructure is in dire straits according to the 2013 American Society of Civil Engineers (ASCE) Report Card, giving America a D+ average for all infrastructure categories. "The World Economic

America's infrastructure is in dire straits according to the 2013 American Society of Civil Engineers (ASCE) Report Card, giving America a D+ average for all infrastructure categories. "The World Economic Forum's Global Competitiveness Report 2014-2015 ranks the U.S. 16th in quality of overall infrastructure" (Peters State). This paper addresses the need for investment in transportation infrastructure starting today, with a focus on bridges. The rates at which infrastructure is being built and maintained is not sustainable. Lack of funding causes states to practice deferred maintenance of infrastructure which ultimately results in higher overall costs. Timely maintenance and investment in current infrastructure is almost always the more economical approach. Despite conditions in Arizona, the rest of America is struggling with crumbling infrastructure. This paper stems from the Tex Wash Bridge failure on the Interstate-10 between California and Arizona in July 2015. A case study of four potential causes of the Tex Wash Bridge's collapse are discussed, along with several solutions that could have lessened the likelihood of failure. The condition of bridges are cataloged in the National Bridge Inventory managed by the Federal Highway Administration. In all reality, cost is not incurred at the instance of a bridge collapse, rather it is incremental throughout the infrastructure's lifetime. The impact of infrastructure failures are economic, social, and political. In the last decade, 33 short term fixes for project funding of roadways have been passed by Congress, none lasting longer than two years. The federal budget's underinvestment in infrastructure limits state departments of transportation ability to address high risk issues. Transportation is funded via the federal gasoline tax and vehicle license tax, along with state gasoline taxes. Unfortunately, the federal gasoline tax has not been increased since 1993. The Highway Trust Fund has subsequently faced insolvency in recent years. In 2011, America only committed 2.4% of its GDP to it's over 4 million miles of roads concluding that there is no interest to make transportation infrastructure a national priority. Currently, each state needs an average of $1 billion to address deficient bridges, and America needs $3.6 trillion to raise infrastructure ratings in the next five years. These needs can only be addressed at the federal level through long-term transportation legislation. It will require gaining investor confidence in tax spending, looking towards alternate funding such county taxes or toll roads, and capitalizing on the immediate interest generated by catastrophes. Mary Peters, former United States Secretary of Transportation, emphasizes the economic impact of underinvestment to foster political will, as opposed to focusing on America's crumbling infrastructure. Public safety and the economy are tied directly to the condition of America's infrastructure. For improvement on the national level, the disconnect between public understanding, engineering judgement, and political action must be remedied. The process starts by making America's infrastructure a national priority.

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Date Created
  • 2016-05

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Demographic Effects on Team Dynamics

Description

Team dynamics: a system of behaviors and psychological processes occurring within a social group (wiki). This definition classifies it as pertaining to a social group, so how do team dynamics

Team dynamics: a system of behaviors and psychological processes occurring within a social group (wiki). This definition classifies it as pertaining to a social group, so how do team dynamics vary from one specific social group to another? Social groups are created for many different reasons, some inherent (such as families) and some created intentionally with knowledge of what is being done (such as athletic teams, class project groups, and groups in the workforce). The way these groups interact and work as a team shapes how efficient they can work and how well they are able to achieve set goals. Therefore, in order to predict how well a particular group or team might perform in a routine project, it is useful to analyze the way they work together on a regular basis. Certain aspects of different groups, such as gender, age, level of competition, and type of activity, cause them to work together in different manners. Do any of these factors cause a particular group to work better as a team? Or do they just cause them to work differently?

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Date Created
  • 2013-05