News Article | May 5, 2017
Seven teams working on technology that could someday be used to create habitats from materials on other worlds have completed the first printing segment of NASA's 3D-Printed Habitat Challenge. NASA has awarded $100,000 to the two top-scoring teams from this stage, the Phase 2: Level 1 Compression Test Competition. Point-based awards were made to Foster + Partners | Branch Technology of Chattanooga, Tennessee, who earned $85,930, and the University of Alaska, Fairbanks, earning $14,070. The 3D-Printed Habitat Challenge is run through a partnership with NASA's Centennial Challenges Program and Bradley University in Peoria, Illinois. The goal of the challenge is to foster the development of technologies to manufacture a habitat using local indigenous materials with, or without, recyclable materials. The vision is that autonomous machines will someday be deployed in deep space destinations, including Mars, to construct shelters for human habitation. On Earth, these same capabilities could be used to produce affordable housing wherever it is needed or where access to conventional building materials and skills are limited. "Seeing tangible, 3D-printed objects for this phase makes the goals of this challenge more conceivable than ever," said Monsi Roman, program manager of Centennial Challenges. "This is the first step toward building an entire habitat structure, and the potential to use this technology to aid human exploration to new worlds is thrilling." The Level 1 Compression Test Competition is the first of three sub-competitions within Phase 2. For this stage, teams were tasked with developing 3D-printable materials, using a 3-D printer, and printing two samples: a truncated cone and a cylinder. Judges evaluated results from lab tests performed on the samples to determine a score. "Innovation is a key focus of Bradley University which is one of the many reasons we are so very proud to be a part of the 3D-Printed Habitat Challenge with NASA," said Bradley University President Gary Roberts. "The winners of Phase 1 and this first stage of Phase 2 are to be commended for their innovation in creating a solution that will fit not only in our world but beyond. I look forward to the next phase and seeing teams work to advance critical systems needed for human space exploration like never before." In addition to the two teams that earned prize money, the other teams participating were: Bubble Base of Winston-Salem, North Carolina; Pennsylvania State University of University Park; CTL Group Mars of Skokie, Illinois; ROBOCON of Singapore; and Moon X Construction of Seoul, South Korea. The teams showcased a variety of approaches, ranging from traditional cement to exotic cellular structures. Teams will now work toward the Level 2 Beam Member Competition, where they must print a beam to be tested. New teams may enter the competition if they can meet minimum requirements. The 3D-Printed Habitat Challenge comprises three phases: Phase 1, the Design Competition, was completed in 2015. Phase 2, the Structural Member Competition, which carries a $1.1 million prize purse and focuses on the material technologies needed to create structural components. Phase 3, the On-Site Habitat Competition, and has a $1.4 million prize purse and focuses on fabrication technologies. NASA's Centennial Challenges Program uses competitions to draw citizen inventors from diverse backgrounds and disciplines to push technology forward for the benefit of space exploration. The Centennial Challenges Program, managed at NASA's Marshall Space Flight Center in Huntsville, Alabama, is part of the agency's Space Technology Mission Directorate. Bradley University has partnered with sponsors Caterpillar, Bechtel and Brick & Mortar Ventures to run the competition. For more information about the competition, visit: http://www.nasa.gov/3DPHab To register for competition and for official rules and documents, visit: http://bradley.edu/challenge/ Please follow SpaceRef on Twitter and Like us on Facebook.
Li L.,University of Tennessee at Knoxville |
Ma Z.J.,University of Tennessee at Knoxville |
Oesterle R.G.,CTL Group
Journal of Bridge Engineering | Year: 2010
This companion paper focuses on an investigation of improved continuous longitudinal joint details for decked precast prestressed concrete girder bridge systems. Precast concrete girders with an integral deck, which are cast and prestressed with the girder, provide benefits of rapid construction along with improved structural performance and durability. Despite these advantages, the use of this type of construction has been limited to isolated regions of the United States. One of the issues limiting more widespread use is the perceived problem with durability of longitudinal joints used to connect adjacent girders. Four full-scale slabs connected by No. 16 (#5) headed reinforcement detail using a 152 mm (6 in.) lap length were fabricated and tested. An analytical parametric study was conducted to provide a database of maximum forces in the longitudinal joint. These maximum forces are then used to determine the loading demand necessary in the slab testing due to the service live load. Static and fatigue tests under four-point pure-flexural loading, as well as three-point flexural-shear loading, were conducted. Test results were evaluated based on flexural capacity, curvature behavior, cracking, deflection, and steel strain. Based on these test results, the improved longitudinal joint detail is a viable connection system that transfers the forces between the adjacent decked bulb tee girders. © 2010 ASCE.
Li L.,University of Tennessee at Knoxville |
Ma Z.,University of Tennessee at Knoxville |
Griffey M.E.,University of Tennessee at Knoxville |
Oesterle R.G.,CTL Group
Journal of Bridge Engineering | Year: 2010
This paper focuses on an investigation of improved continuous longitudinal joint details for decked precast prestressed concrete girder bridge systems. Precast concrete girders with an integral deck that is cast and prestressed with the girder provide benefits of rapid construction along with improved structural performance and durability. Despite these advantages, use of this type of construction has been limited to isolated regions of the United States. One of the issues limiting more widespread use is a perceived problem with durability of longitudinal joints used to connect adjacent girders. This paper presents the results of a study to assess potential alternate joint details based on constructability, followed by testing of selected details. Seven reinforced concrete beam specimens connected with either lapped headed reinforcement or lapped welded wire reinforcement were tested along with a specimen reinforced by continuous bars for comparison. Test results were evaluated based on flexural capacity, curvature at failure, cracking, deflection, and steel strain. Based on the survey and the experimental program, a headed bar detail with a 152 mm (6 in.) lap length was recommended for replacing the current welded steel connector detail. © 2010 ASCE.
News Article | February 15, 2017
A new fact sheet from the Indiana Limestone Company presents Solar Reflectance Index (SRI) performance data for four of the company’s outstanding stone products. As the sheet makes clear, all of the products exceed LEED 2009 and LEED v4 requirements. SRI measures the ability of a constructed surface to reflect solar heat. Designing with high-SRI materials like Indiana Limestone products is important because it can reduce the "heat island effect" commonly associated with urban areas. Highly concentrated building materials and pavement absorb large amounts of the sun's energy, get hot, and then warm the surrounding air. This warms the whole area, often creating a warmer micro-climate which leads to higher energy consumption. Tests that produced the results shown in the fact sheet were carried out by CTL Group, Skokie, IL. The SRI for the four products was calculated according to ASTM E1980. The results indicating the excellent SRI performance of Indiana Limestone Company products are: LEED is a rating system devised by the United States Green Building Council to evaluate buildings’ environmental performance. The SRI reference sheet is available online at IndianaLimestoneCompany.com, along with a wealth of additional information about the company and its products. About Indiana Limestone Company Indiana Limestone Company is unmatched as the premier supplier of Indiana Limestone in a range of beautiful and lasting building products. Founded in 1926 (with predecessor firms that had been quarrying limestone since the mid-1800s), ILCO today remains the provider of choice for this internationally renowned natural stone. Throughout an illustrious history in which its stone has made such iconic structures as the Empire State Building, National Cathedral, and the Pentagon, ILCO has reliably provided the highest quality products and services carefully tailored to the needs of the market with an environmental, natural focus.
Ideker J.H.,Oregon State University |
Bentivegna A.F.,CTL Group |
Folliard K.J.,University of Texas at Austin |
Juenger M.C.G.,University of Texas at Austin
ACI Materials Journal | Year: 2012
Traditional laboratory methods for identifying alkali-silica reactive aggregates (ASTM C1260 and C1293) sometimes produce inaccurate and conflicting results. To benchmark these tests and ultimately develop a more realistic test method(s), an outdoor exposure site was constructed to simulate field performance of concrete incorporating reactive aggregates. It was found that the performance of the aggregates in the laboratory and field environments varied considerably. ASTM C1260 was a good indicator of reactivity for some aggregates. In many cases, however, the results from ASTM C1260 disagreed with those from ASTM C1293 and the outdoor simulated field tests. In general, reactivity diagnosed by ASTM C1293 was found to correlate well with reactivity in field exposure. However, when ASTM C1293 was modified to evaluate lower alkali loadings, the test was unable to predict expansion in outdoor specimens. Copyright © 2012, American Concrete Institute. All rights reserved.
Grasley Z.C.,Texas A&M University |
DAmbrosia M.D.,CTL Group
Cement and Concrete Composites | Year: 2011
Passive restrained concrete ring experiments provide enough information to extract useful aging viscoelastic constitutive properties when combined with free drying shrinkage and mass loss experiments. In this paper, analytical techniques are described for deriving a closed-form solution to extract the viscoelastic Young's modulus from solidifying concrete in a restrained concrete ring test. Using limit theorems, approximate closed-form solutions are derived for the non-uniform internal relative humidity (RH), free drying shrinkage, and tangential stress gradients. An example problem demonstrates the utility of the derived solutions and illustrates the effect that viscoelastic relaxation and solidification have on the tangential stress profile in the restrained, drying concrete ring. Both viscoelastic and solidification effects have a significant impact on the predicted stress profile. © 2010 Elsevier Ltd. All rights reserved.
Wyatt S.T.,CTL Group
American Concrete Institute, ACI Special Publication | Year: 2010
Highway bridges are periodically exposed to fires that can cause severe and extensive damage to critical components. After such an occurrence, bridge owners are immediately faced with several critical questions, including: • Is the structure safe for use by the public? • Does the damaged bridge require load posting? • How has the service-life been affected? • What repair or rehabilitation alternatives are available? To properly answer owner concerns regarding the safety and serviceability of critical infrastructure, a complete evaluation consisting of visual inspection, Non-Destructive Testing (NDT), and laboratory testing is required. The objective of the evaluation is to identify the depth and extent of fire damage as well as any change in the physical or material properties in the steel and concrete. This paper entails a discussion of fire related damage mechanisms to highway structures, NDT methods and technologies available for evaluation of fire-damaged bridge elements and repair alternatives to return bridges to safe operation and restore the intended service life. Three case studies will be discussed to demonstrate application of the inspection and evaluation process presented.
Roller J.J.,CTL Group |
Lotfi H.R.,CTL Group
Pipelines 2015: Recent Advances in Underground Pipeline Engineering and Construction - Proceedings of the Pipelines 2015 Conference | Year: 2015
In 1992, the American Water Works Association (AWWA) introduced a new standard for the design of prestressed concrete cylinder pipe (PCCP) designated as ANSI/AWWA C304. The ANSI/AWWA C304 Standard introduced a new design philosophy for PCCP based on the concept of evaluating and satisfying certain serviceability, elastic and strength limit-states criteria using various combinations of factored and unfactored design loads and internal pressures. When the C304 Standard was first introduced in 1992, many potential users voiced concerns related to the complexity of the design provisions contained therein that continue to date. Upon performing a detailed review of the C304 Standard, it is apparent to the authors that some of the provisions currently incorporated in the document can be simplified without any significant corresponding consequences relative to the final overall design solution. This paper addresses some of these overly-complex design provisions and provides alternate or simplified provisions for a few of them. In the near future, the authors anticipate performing a more comprehensive evaluation and preparing additional supplementary publications with the intention of providing further justification for simplifying future versions of the ANSI/AWWA C304 Standard. © 2015 ASCE.
Cao H.,CTL Group
Materials Evaluation | Year: 2010
When applied appropriately, NDT techniques can be used to test large concrete structures with confidence. NDT causes the least disruption and provides valuable information about the structural condition, beyond that which can be seen by the inspector's eye. Application of each technique must be planned and carefully thought out based on the specific structural geometry, accessibility and evaluation objective. Indepth knowledge and experience of the applied test technique is required to make sound interpretation of collected data. When feasible, trial testing or mock-ups are very beneficial in defining a suitable test program. As power plants age, potential deterioration of concrete infrastructure prompts the need for structural and durable evaluation in association with relicensing applications. Further, when structures fail to perform in accordance with design expectations, investigation into the root cause often includes application of concrete NDT. Application of these technologies in the energy industry is expected to increase in the upcoming years.
Bassam A.,CTL Group |
Iranmanesh A.,University of Illinois at Chicago |
Ansari F.,University of Illinois at Chicago
Engineering Structures | Year: 2011
Conventional methods for displacement based condition assessment of bridges solely rely on the maximum level of displacements experienced by the piers, and do not take into account the accumulated damage that result from cyclic loading. More advanced approaches take this into account by considering the structural damage as a linear combination of the normalized maximum displacements and hysteretic energy. Computation of the dissipated hysteretic energy requires monitoring of the lateral forces during the seismic events, which are not as practical as monitoring bridge pier deformations. This article reports on the development of a simple damage assessment method that considers the effect of cyclic loading on the state of damage and it is merely based on monitoring the bridge pier deformations. A fiber optic displacement serial array was designed for measuring the crack opening displacement reversals at the plastic hinge areas. © 2011 Elsevier Ltd.