Design method of piled-raft foundations under vertical load considering interaction effects
Author: Dang Dinh Chung Nguyen, Seong-Bae Jo, Dong-Soo Kim | Size: 1.52 MB | Format:PDF | Quality:Original preprint | Publisher: Computers and Geotechnics Volume 47, | Year: January 2013 | pages: 16–27
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I was wondering if someone could help me find an article from Journal of Seismology:
Strasser, F., Bommer, J., Abrahamson, N. (2008)."Truncation of the distribution of ground-motion residuals". Journal of Seismology, vol. 12(1), 79-105.
Hi
please share this document; Development of Fragility Curve Considering Aging of Oil Storage Tanks and Its Application to Risk Assessment of Industrial Complexes
by: Yoshihisa Murakami
ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference (PVP2010)
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Small-Scale Modeling of Reinforced Concrete Structural Elements for Use in a Geotechnical Centrifuge
Author: Knappett, J., Reid, C., Kinmond, S., and O’Reilly, K. | Size: ?? MB | Format:PDF | Quality:Unspecified | Publisher: Journal of Structural Engineering | Year: 2011 | pages: 9
This paper discusses the modeling of reinforced concrete structural elements for use in geotechnical centrifuge modeling of soil-structure interaction problems. Centrifuges are employed in geotechnical modeling so that the nonlinear constitutive behavior of soil in small-scale models can be correctly modeled at prototype scale. Such models typically necessitate large scale factors of between 1∶20 and 1∶100, which is significantly larger than most conventional small-scale structural modeling. A new model concrete has been developed consisting of plaster, water, and fine sand as a geometrically scaled coarse aggregate that can produce a range of model concretes with cube compressive strengths between 25–80 MPa. Reinforcement is modeled using roughened steel wire (beams) or wire mesh (slabs). To illustrate the validity of the modeling technique, a series of three- and four-point bending tests were conducted on model beams designed to represent a 0.5×0.5 m square section prototype beam at 1∶40 scale, and model slabs designed to represent a prototype slab with plan dimensions of 4.8×4.8 m and 0.4 m deep (also at 1∶40 scale). The amount of longitudinal reinforcement was varied and tests both with and without shear reinforcement were conducted. The models were able to accurately reproduce both shear and flexural (bending) failures when loaded transversely. The load capacity (strength), bending stiffness, and ductility were shown to be simultaneously and appropriately scaled over a range of scaling factors appropriate for geotechnical centrifuge testing, and the technique therefore provides a significant improvement in the ability to accurately model soil-structure interaction behavior in centrifuge models.
An adequate longitudinal joint tie bar system is essential in the overall performance of concrete pavement. Excessive longitudinal joint openings are believed to be caused by either inadequate tie bar size or spacing or improper tie bar installation. If designed and installed properly, tie bars prevent the joints from opening and consequently improve load transfer efficiency between slabs and between slabs and shoulders, resulting in increased load carrying capacity. This study evaluated the longitudinal joint tie bar system currently used by CDOT, examining the criteria for proper use of tie bars and determining the maximum number of lanes that can be tied together without negatively impacting the concrete pavement structure. An improved mechanistic-empirical tie bar design method was developed. Tie bar design tables with recommended bar size and spacing were provided for each combination of pavement base types, CDOT concrete mixes, and weather stations. Field studies were conducted to investigate longitudinal joint performance and further evaluate the impact of factors related to design and construction practices. The experimental plan for this round of testing included the evaluation of tie bar alignment, measurement of joint load transfer, and measurement of relative slab movement at the joints. In addition, CDOT’s current specifications and practices related to longitudinal joint construction and tie bar design and placement were compared with those of other state agencies. Field testing results revealed that the measured joint openings at some tied longitudinal joints were in the typical range of non-tied slabs, implying that some tied joints performed as poorly as non-tied slabs. The results indicate the possibility of tie bar failure due to loss of concrete-steel bonding or yielding of tie bar steel. Another key finding was the possible impact of tie bar misalignment or misplacement on poor longitudinal joint performance. Testing indicated that the measured joint openings were wider when the tie bars did not connect to the other side of the joint, or when the embedment lengths were inadequate. On the other hand, tie bars with adequate embedment length on both sides of the joint, even when misaligned, appear to hold the joint tight. CDOT should adopt the mechanistic-empirical tie bar design procedure developed in this study. The research team recommends that CDOT conduct more rigorous experimental and field testing covering various base material types and concrete mixtures to obtain Colorado-specific model parameters for implementation.
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Synthesis of Performance Testing of Asphalt Concrete
Author: Dave, Eshan V Koktan, Philip | Size: 678 KB | Format:PDF | Quality:Original preprint | Publisher: University of Minnesota, Duluth | Year: 2011 | pages: 90
At present, like many other agencies, the Minnesota Department of Transportation asphalt material specifications rely primarily on volumetric properties to ensure good field performance. There have been considerable amounts of research efforts to develop so called “asphalt performance tests” that can link laboratory-measured parameters to pavement performance. Research efforts are also undertaken to refine the asphalt mix-design method so that laboratory tests and procedures can be incorporated into material specification. This research project explored availability of such tests, their suitability, and their use by other agencies.
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Finite Element Analysis of Deep Wide-Flanged Pre-stressed Girders to Understand and Control End Cracking
Author: Oliva, Michael G University of Wisconsin, Madison Okumus, Pinar | Size: 9.48 MB | Format:PDF | Quality:Original preprint | Publisher: University of Wisconsin, Madison | Year: 2011 | pages: 132
Hundreds of prestressed concrete girders are used each year for building bridges in Wisconsin. The prestress transfer from the prestressing strands to concrete takes place at the girder ends. Characteristic cracks form in this end region during or immediately after detensioning. Potential solutions to control end cracking were examined via finite element models and the impact of each solution on cracking was evaluated. Modifications to reinforcement bar size, debonding ratios, strand cutting sequence and use of draped strand patterns were simulated by the models. The results from different analyses were compared to quantify the success of each method in reducing strains causing girder end cracks. The tension strains leading to cracks of all types were responsive to debonding some of the bottom flange prestressing strands. Bottom flange cracking can be prevented by methodically debonding exterior strands, keeping the draped strands bonded, and evenly distributing the remaining bonded strands over the bottom flange.
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Numerical Modeling and Experimental Investigation of the Local Hydrology of a Porous Concrete Site
Author: Syrrakou, Christina Pinder, George | Size: 9.56 MB | Format:PDF | Quality:Original preprint | Publisher: University of Vermont, Burlington | Year: 2011 | pages: 86
Although porous pavement use has been accepted as a successful stormwater management practice in warm climates, application in regions with colder climates, like New England, is still under investigation. The Randolph Park and Ride Site, which is the area of interest of this specific study, is the first porous concrete site constructed in Vermont. The site, which was built in 2008 and is under use up to today, is quite unique in terms of the geology of the underlying materials and also the extensive instrumentation that has been applied in the field. The purpose of building this site was in part commercial, to provide the town of Randolph with a public parking lot, and part experimental, aimed at giving insight to the optimal design of porous pavements in New England. This study focuses on the experimental use of the site. The study initially aims at investigating the interaction between porous concrete utilization and local hydrology at porous concrete sites in New England. With this part achieved, a mathematical model can be developed and used prior to construction as a design tool for other porous concrete sites. It is also a secondary goal of this study to combine the mathematical model created with an optimization algorithm that will allow for optimal design of porous concrete sites in terms of minimal expense.
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