Failure Investigation of the Steel Strut of Paseo Suspension Bridge

A vertical strut of the 1232-foot long, self-anchored Paseo Suspension Bridge fractured when the temperature hit at a record low of 9°F below zero. During inspection the following day, it was found that its lower pin was frozen and did not allow for free movement of the superstructure. The objective of this study is to pinpoint one of the four reasons for this incidence or their combination: overstressing, thermal contraction, fatigue, and reduction in fracture toughness at low temperatures. To achieve this objective, material property and fatigue testing was performed on samples of strut material while the bridge and strut were analyzed under service loading conditions. This study indicated that the strut material practically has an infinite life under normal conditions. The root cause of the failure is overstressing of the vertical strut due to a frozen pin that became frozen because the design of the bridge did not allow the pin to be maintained. The mechanically frozen pin condition was attributable to salt and sand accumulation in the strut housing. To prevent this to the new struts and other similar structures, it is recommended that both upper and lower pins be greased during special inspections and the lower housings be partially sealed to prevent salt and sand accumulation near the pins. Alternatively, a rotation monitoring system can be installed to remotely monitor the rotation of all four vertical struts and alert officials should the pins become mechanically frozen

Engineering Lessons Learned from Fracture Failure of the Paseo Suspension Bridge

One of the four vertical struts in the 1232-foot long Paseo Suspension Bridge fractured on January 22, 2003. Fatigue in normal conditions, overstressing and thermal contraction as a result of frozen pin conditions, as well as reduction in fracture toughness at low temperatures were identified as four relevant factors. To ascertain the most likely reason(s), material, fatigue, aad fracture tests were performed on samples of the strut material while the bridge and strut were analyzed under service loading conditions. Numerical results and test data indicated that fatigue was not the primary reason for the fractured strut as supported by the visual inspection done two months prior to the incidence and the presence of a rough fracture surface. It was the mechanically frozen pin condition at the lower end of the strut that resultedinm an unexpected benduig stress and thus sudden to salt and sand accumulation in the strut housing. Low temperature was a contributing factor. An engineering lesson learned from this incidence was that the original design did not allow for routine maintenance without disassembling the fink housing system

Engineering Lessons Learned from Fracture Failure of the Paseo Suspension Bridge

One of the four vertical struts in the 1232-foot long Paseo Suspension Bridge fractured on January 22, 2003. Fatigue in normal conditions, overstressing and thermal contraction as a result of frozen pin conditions, as well as reduction in fracture toughness at low temperatures were identified as four relevant factors. To ascertain the most likely reason(s), material, fatigue, aad fracture tests were performed on samples of the strut material while the bridge and strut were analyzed under service loading conditions. Numerical results and test data indicated that fatigue was not the primary reason for the fractured strut as supported by the visual inspection done two months prior to the incidence and the presence of a rough fracture surface. It was the mechanically frozen pin condition at the lower end of the strut that resultedinm an unexpected benduig stress and thus sudden to salt and sand accumulation in the strut housing. Low temperature was a contributing factor. An engineering lesson learned from this incidence was that the original design did not allow for routine maintenance without disassembling the fink housing system

6th Graders in STEM: Development of an International Climate Team and Weather Station at Washington Elementary

While opportunities to become involved in climate and STEM-related clubs exist at the middle and high school levels in Idaho, few are available at elementary schools. This project establishes Boise’s first International Climate Team (ICT) at Washington Elementary to address this need. Within the program, 6th graders maintain their own school weather station, interpret local weather and climate, establish a new STEM Club, and develop team leadership skills. In conjunction with service learning partners at Washington Elementary, the Boise School District, and Boise State University we mentor the ICT and STEM club and provide support for the installation and data analysis for the new Washington weather station. We follow ICT guidelines developed by Cedillo under a professional model for both middle and high schoolers at Marsing Middle School and East Junior High. These students participate in activities such as Arduino programming, partnering with international schools, school weather forecasting, videography and tutorial creation. Project development will continue through spring of 2020. Initial meets demonstrate Washington Elementary 6th graders dedication to the student-run STEM Club, International Climate Team, and maintaining their own weather station, with preliminary results indicating that the ICT model is viable at the upper-elementary level

The Scotch Parallel Storage Systems

To meet the bandwidth needs of modern computer systems, parallel storage systems are evolving beyond RAID levels 1 through 5. The Parallel Data Lab at Carnegie Mellon University has constructed three Scotch parallel storage testbeds to explore and evaluate five directions in RAID evolution: first, the development of new RAID architectures to reduce the cost/performance penalty of maintaining redundant data; second, an extensible software framework for rapid prototyping of new architectures; third, mechanisms to reduce the complexity of and automate error-handling in RAID subsystems; fourth, a file system extension that allows serial programs to exploit parallel storage; and lastly, a parallel file system that extends the RAID advantages to distributed, parallel computing environments. This paper describes these five RAID evolutions and the testbeds in which they are being implemented and evaluated

The Scotch Parallel Storage Systems (CMU-CS-95-107)

To meet the bandwidth needs of modern computer systems, parallel storage systems are evolving beyond RAID levels 1 through 5. The Parallel Data Lab at Carnegie Mellon University has constructed three Scotch parallel storage testbeds to explore and evaluate five directions in RAID evolution: first, the development of new RAID architectures to reduce the cost/performance penalty of maintaining redundant data; second, an extensible software framework for rapid prototyping of new architectures; third, mechanisms to reduce the complexity of and automate error-handling in RAID subsystems; fourth, a file system extension that allows serial programs to exploit parallel storage; and lastly, a parallel file system that extends the RAID advantages to distributed, parallel computing environments. This paper describes these five RAID evolutions and the testbeds in which they are being implemented and evaluated

Biallelic VARS variants cause developmental encephalopathy with microcephaly that is recapitulated in vars knockout zebrafish

Aminoacyl tRNA synthetases (ARSs) link specific amino acids with their cognate transfer RNAs in a critical early step of protein translation. Mutations in ARSs have emerged as a cause of recessive, often complex neurological disease traits. Here we report an allelic series consisting of seven novel and two previously reported biallelic variants in valyl-tRNA synthetase (VARS) in ten patients with a developmental encephalopathy with microcephaly, often associated with early-onset epilepsy. In silico, in vitro, and yeast complementation assays demonstrate that the underlying pathomechanism of these mutations is most likely a loss of protein function. Zebrafish modeling accurately recapitulated some of the key neurological disease traits. These results provide both genetic and biological insights into neurodevelopmental disease and pave the way for further in-depth research on ARS related recessive disorders and precision therapies.status: publishe