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Home > Events > Conventions > Current Convention > Sessions and Events
C = Duke Energy Convention Center; H = Hyatt Regency Cincinnati
Prestressed Concrete with Conventional and Nonconventional Materials, Part 2 of 2
Mon, October 21, 2019 1:30 PM - 3:30 PM, C-Junior Ballroom C
Professor Hiroshi Mutsuyoshi of Japan Prestressed Concrete Institute is co-moderating a special session will focused on the recent advancement of prestressed concrete for bridges and structures using conventional and nonconventional materials. Presentations and technical papers will include the conceptual development of innovative prestressed concrete, laboratory experiments, numerical modeling, and case studies. State-of-the-art prestressing techniques and nonconventional materials such as fiber reinforced polymer (FRP) composites to address the sustainable performance of concrete members will also be considered. The session will benefit practicing engineers, government officials, and academics. Learning Objectives: 1) Review the importance of non-conventional materials for bridge girders;(2) Identify structural demand for prestressed bridge girders;(3) Recognize the use of emerging materials in precast application;(4) Develop new concepts for concrete bridge design.This session has been AIA/ICC approved for 2 CEU/PDH credits.
Prestressed Concrete using Calcium Sulfoaluminate Cement
Presented By: Cameron Murray
Affiliation: University of Arkansas
Description: Calcium Sulfoaluminate-Belite (CSA) cement is a hydraulic cement which sets rapidly and gains strength very quickly. With CSA cement, strengths of 4 ksi in as little as 2 hours are possible under many environmental conditions with no steam curing. The dimensional stability of CSA cement concrete is also superior to portland cement. These advantages make CSA cement an enticing material for precast-prestressed concrete. This talk reviews ongoing research on CSA cement for prestressed concrete beams. The authors have cast prestressed concrete beams using CSA cement at commercial precast facilities and in a lab setting. These studies have shown that it is feasible to release prestress in 2-4 hours using CSA cement, and that many properties of these beams are at least as good, if not better than portland cement. Transfer lengths, development lengths, flexural strengths, and prestress losses were measured in these studies. Despite some unique difficulties of working with a rapid setting product, prestress force was released in as little as two hours with no adverse effects. The properties of the beams will be reviewed in this talk to highlight the potential of this material for precast prestressed construction.
Impact of Void Details on the Performance of Hollow Pretensioned Concrete Bent Caps
Presented By: Codi McKee
Affiliation: Texas AM University College Station
Description: While precast bent caps can be of significant benefit for accelerated bridge construction, weight can become a limiting factor for wide bridges. Pretensioned bent caps with interior voids for weight reduction offer an attractive alternative. Subassemblies of hollow pretensioned concrete bent caps, including the column and connection region without an interior void, were tested to allow for examination of the performance of voids within a multi-column substructure. The location of void termination was varied to assess the impact on development of cracks and failure mechanisms. To better assess these, a grid of LED targets was used to measure displacements in the void termination region. Readings were used to infer strains. Evaluation of principal tensile strains correlate to observed crack damage and the regions of largest principal compressive strains indicate the regions of the bent caps where failure ultimately occurs. Collected data can be used for the validation of numerical models to further assess void details on the performance of hollow prestressed concrete beams.
Distributed Horizontal Shear Reinforcement to Mitigate Shear Failures at End Regions of Pretensioned Beams
Presented By: Bruce Russell
Affiliation: Oklahoma State University
Description: In the 1994 Northridge Earthquake, precast, prestressed double tees and inverted tees suffered collapse caused by larger than normal vertical accelerations, and the resulting high internal shears that were applied to the members. The episode highlighted the need to provide additional anchorage for the longitudinal tension forces necessary to resist shear forces at or very near the support for pretensioned members. The smooth nature of prestressing strands and its lack of mechanical anchorage can present problems in shear. The smooth wire strands struggle to develop adequate anchorage near end regions where development of tension capacity is not assured. The research presented shows that cracking in end regions can be mitigated by distributing longitudinal mild reinforcement within narrow webs and stems of precast, prestressed concrete beams. By limiting the propagation of shear cracks, the reinforcement also mitigates damage to the anchorage zone and thus improves the strands’ ability to develop tension forces near the end of the member. Additionally, alternative load paths are provided which enable re-distribution of the shear deformations and allows alternative load paths for shear forces. Shear vs. strain relationships, similar to the modified compression field theory are developed based on measurements from testing, which can provide a rational basis for design. Alternatively, analysis techniques that focus on variations of strut and tie modeling are described. These are also discussed in terms of design techniques.
Field Deployment of CFCC in Highway Bridge Applications
Presented By: Yoshiaki Yamamoto
Affiliation: Tokyo Rope International
Description: Applications of Carbon Fiber Composite Cable (CFCC) will be presented for highway bridges.
Prestressed NSM CFRP for Highway Bridges: from Modeling to World-First Field Application
Presented By: Yail Jimmy Kim
Affiliation: University of Colorado Denver
Evaluation and 3D Visualization of Non-Destructive Testing Data for Prestressed and Reinforced Concrete Structures
Presented By: Wael Zatar
Affiliation: Marshall University