ATLSS Engineering Center Tour
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Lehigh University’s Advanced Technology for Large Structural Systems (ATLSS) Engineering Research Center is a world-renowned leader in research, development and full scale testing and evaluation of large structural systems in the civil infrastructure. The research projects focus on life-cycle evaluation and damage assessment of structural systems and materials for the infrastructure, developing new systems and materials for improved service performance, assessing the condition of existing systems and materials, developing non-destructive evaluation and monitoring technology for condition assessment, forensic investigation of structural system and material failures, and developing technology for repairing and retrofitting existing systems. The laboratory is currently active with several projects including some of largest research projects on fatigue and fracture in the infrastructure. ATLSS also houses the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) real time multi-directional test facility, which is a national
networked collaboration of geographically-distributed, shared-use experimental research equipment sites around the country.
A tour of the ATLSS multi-directional testing facility is scheduled for Sunday, July 26, 2009. Cost for this tour is included in the conference registration. Bus seating is limited, so reserve your seat today while registering for the conference.
An overview of some of the projects and facilities that will be discussed as part of the ATLSS tour is provided below.
ACTIVE FATIGUE AND FRACTURE RELATED ATLSS PROGRAMS
Fatigue Evaluation of the Full Scale Orthotropic Replacement Deck for the Verrazano Narrows Bridge in New York City
The Triborough Bridge and Tunnel Authority (Metopolitan Transportation Agency), New York City is replacing the upper level concrete filled grid deck of the Verrazano Narrows Suspension Bridge with a steel orthotropic deck as part of the bridge rehabilitation. The steel orthotropic deck is lighter and therefore increases the longevity of the bridge cables. Accordingly, this deck is a favorite choice for long span and movable bridges. However, due to lack of good design practices and existence of large number of fabrication intensive complex welded connections, extensive fatigue cracking has been reported in this type of deck in many bridges around the world. Field performance and laboratory testing have demonstrated that if properly designed, this deck can provide a hundred year service life with minimum maintenance. Lehigh University’s ATLSS Center is conducting fatigue testing of a full scale prototype of the replacement deck for the Verrazano Narrows Bridge, which has been designed by the Parsons Transportation Group, New York City. The test specimen contains a part of the entire rehabilitated bridge deck including floor beams and stringers and is being loaded by nine actuators simultaneously to simulate dead load deformation and passage of truck loading across the deck. This test is unique in that it is rarely performed due to the level of efforts involved. The ATLSS Center is the only facility around the world that specializes in large scale testing of this magnitude.
NCHRP Project 10-70: Cost-Effective Connection Details for Highway Sign Luminaire and Traffic Signal Structures
Full scale fatigue testing of cantilevered highway sign/traffic signal and high level luminaire (high mast lighting) structures is being conducted at Lehigh University’s ATLSS Center and Fritz Laboratory as part of an ongoing research under NCHRP Project 10-70. In the past two decades, fatigue cracking of these structures is increasingly being reported all over the United States, which has significant economic impact on the limited infrastructure resources. The provisions of the existing AASHTO specification are often inadequate in designing these structures against service limit state in
fatigue and non-conformities exist between the recommended fatigue categories and the limited test results for these details. The current research encompasses assessment of fatigue performance of the welded connections that are commonly used in these structures. These welded connections include the socket connection, the groove welded connection, the stiffened sockets, the arm to pole gusset, the ring stiffened arm to pole connection, reinforced and un-reinforced hand holes, and jacket retrofits. In total, 74 specimens, including full size signal/sign structures and high mast towers, are being tested under this project, with 8 specimens tested simultaneously. To-date, this project is the largest comprehensive effort in evaluating fatigue performance of the subject structures around the world.
ADDITIONAL ACTIVE ATLSS PROGRAMS
Self-Centering Damage-Free Seismic-Resistant Steel Frame Systems
This project is investigating a family of innovative self-centering (SC) steel frame systems with the potential to withstand the currently accepted design basis earthquake (DBE) for buildings without damage. The project goals are: to develop fundamental knowledge of the seismic behavior of SC steel frame systems; to conduct integrated design, analysis, and experimental research on SC steel frame systems, using the enabling facilities of the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES); to develop performance-based, reliability-based seismic design procedures and criteria for SC steel frame systems; and to educate students and practitioners with fundamental and practical knowledge about SC steel frame systems. Unlike conventional earthquake-resistant steel frame systems that are designed to develop significant inelastic deformations under the DBE resulting in significant damage as well as residual drift, the innovative SC steel frame systems developed by the project have the potential to avoid structural damage under the DBE as a result of several features.
