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Dinh H.H.,Moffatt And Nichol Engineers | Dinh H.H.,University of Michigan | Parra-Montesinos G.J.,University of Michigan | Wight J.K.,University of Michigan
Journal of Structural Engineering | Year: 2011

A simple model is presented to estimate the shear strength of steel fiber reinforced concrete (FRC) beams without stirrup reinforcement. The model was developed on the basis of observations from tests of 27 large-scale beams under monotonically increased concentrated loading. Three types of hooked steel fibers were evaluated in volume fractions ranging between 0.75% (59 kg/m3 or 100 lb/yd3) and 1.5% (118 kg/m3 or 200 lb/yd 3). All but one beam failed in shear either prior to or after flexural yielding. In the proposed model, shear in steel FRC beams is assumed to be resisted by shear stress carried in the compression zone and tension transferred across diagonal cracks by steel fibers. Shear carried in the compression zone is estimated by using the failure criterion for concrete subjected to combined compression and shear proposed by Bresler and Pister. The contribution from fiber reinforcement to shear strength, on the other hand, is tied to material performance obtained through standard ASTM 1609 four-point bending tests. Comparison of predicted versus experimental shear strengths for a large number of FRC beams tested in this and other investigations indicates that the proposed model is capable of predicting the shear strength of steel FRC beams with reasonable accuracy; mean and standard deviation values are 0.79 and 0.12, respectively. © 2011 American Society of Civil Engineers. Source

Deng Y.,Moffatt And Nichol Engineers
Structures Congress 2013: Bridging Your Passion with Your Profession - Proceedings of the 2013 Structures Congress | Year: 2013

Seismic issues are international interests. Non-linear Time History Analysis simulates the structure behavior under severe Earthquake movement more properly than other methods. In this paper, Non-linear time history analysis will be presented with one of the world famous project. Yerba Buena Island (YBI) West-Bound (WB) Ramps are portion of San Francisco-Oakland Bay Bridge Project. The Ramps are touched down to Yerba Buena Island (YBI) from YBI WB Widening by hinges. This project is located at a 0.627g Site Specific Response for Safety Evaluation Earthquake (SEE). YBI WB On-ramp is a highly horizontally Curved Bridge with radius of 127.3 feet (38.8 meters). Seismic behavior is very important for the project. In order to understand structural non-linear behavior, especially highly horizontally curved bridge behavior under severe earthquake events, YBI WB On-ramp stand-alone bridge is analyzed by non-linear time history analysis method. SAP 2000 with Hilber-Hughes-Taylor α direct integration method is used for Non-linear Time History Analysis (NL-THA). Seismic Modeling is discussed in this paper. Then six sets of acceleration time histories are used for NL-THA by SAP 2000. Open System for Earthquake Engineering Simulation (Open-SEEs) program developed by University of California-Berkeley is used to verify the SAP NL-THA accuracy in this paper. Site Specific Response Spectra ARS is also used for liner analysis and compared with results of Non-linear Time History Analysis and Open-SEEs Analysis. Non-linear push-over analysis is performed to determine the structural capacity and ductility under severe earthquake events. Finally, discrepancies between different program analyses are discussed and recommendations are presented. © 2013 American Society of Civil Engineers. Source

Xing X.,Moffatt And Nichol Engineers | Kou Z.,University of Southern California | Huang Z.,University of Southern California | Lee J.-J.,University of Southern California
Pure and Applied Geophysics | Year: 2013

Tsunamis waves caused by submarine earthquake or landslide might contain large wave energy, which could cause significant human loss and property damage locally as well as in distant region. The response of three harbors located at the Pacific coast (i.e. Crescent City Harbor, Los Angeles/Long Beach Port, and San Diego Harbor) to six well-known tsunamis events generated (both near-field and far-field) between 2005 and 2011 are examined and simulated using a hybrid finite element numerical model in frequency domain. The model incorporated the effects of wave refraction, wave diffraction, partial wave reflection from boundaries, entrance and bottom energy dissipation. It can be applied to harbor regions with arbitrary shapes and variable water depth. The computed resonant periods or modes of oscillation for three harbors are in good agreement with the energy spectral analysis of the time series of water surface elevations recorded at tide gauge stations inside three harbors during the six tsunamis events. The computed wave induced currents based on the present model are also in qualitative agreement with some of the reported eye-witness accounts absence of reliable current data. The simulated results show that each harbor responded differently and significantly amplified certain wave period(s) of incident wave trains according to the shape, topography, characteristic dimensions and water depth of the harbor basins. © 2012 Springer Basel AG. Source

Heffron R.,Moffatt And Nichol Engineers
Ports 2013: Success Through Diversification - Proceedings of the 13th Triennial International Conference | Year: 2013

Waterfront infrastructure represents a significant investment and owners have a vested interest in maintaining and extending the service life of these aging assets. Exposed to the harsh marine environment, these assets are subject to degradation more than most non-marine assets. In addition, most owners are interested in protecting life safety and the environment through proactive and cost-effective maintenance. Recognizing these drivers, the ASCE/COPRI Ports & Harbors Committee's Waterfront Inspection Task Committee has developed a new manual to guide the inspection of waterfront assets. The new manual, "Waterfront Facilities Inspection and Assessment Standard Practice Manual," provides comprehensive guidance for the inspection and maintenance of waterfront structures both above water and underwater, as well as associated mooring hardware, fender systems, utilities, and appurtenant features. Eight inspection types are defined in the manual, with each inspection performed for a specific purpose using a tailored scope of work. Inspection types may also be combined and performed simultaneously. The eight inspection types include: Routine Inspection Structural Repair or Upgrade Inspection New Construction Inspection Baseline Inspection Due Diligence Inspection Special Inspection Repair Construction Inspection Post-Event Inspection The manual provides guidance on modeling service life using software such as STADIUM® to provide quantitative solutions to extending the life of waterfront structures. The manual covers every type of waterfront structure type commonly in use. Specific guidance is provided on the nuances of each structure type and the defects commonly found. The structure types covered include: piers (jetties), wharves (quays), bulkheads (quaywalls), seawalls, relieving platforms, gravity block walls, caissons and cofferdams, wave screens/attenuators, marinas, boat ramps, marine railways, floating structures, mooring buoys (SPMs, MBMs, etc.), and slope/shoreline protection. The intent of the manual is to provide owners and specifiers with guidance on what type of inspection to choose for a particular facility need, making the process simpler and more uniform since the scope of each inspection type is defined. The result is a standardized process that will assist owners in maintaining their waterfront assets and extending the service life proactively. © 2013 American Society of Civil Engineers. Source

Kotulak P.W.,Moffatt And Nichol Engineers
Ports 2013: Success Through Diversification - Proceedings of the 13th Triennial International Conference | Year: 2013

As a component of the Masonville Dredged Material Containment Facility (DMCF) project, the Maryland Port Administration (MPA) was required to develop a compensatory mitigation package to offset impacts associated with filling approximately 130 acres of open water in the Patapsco River, which is a major tributary to the Chesapeake Bay. The mitigation approved for the project is a comprehensive package of inwater and upland environmental restoration projects totaling over $20 million, primarily located adjacent to the DMCF in 90 acres of open water and 54 acres of uplands that comprise Masonville Cove. The projects serve to enhance the environment and provide improved habitat and increased wildlife use of the area, in addition to remediating contamination from historical industrial usage and dumping. The projects discussed in this paper include over 2 miles of shoreline restoration and stabilization using created fringe marshes with sandy beaches and living shorelines behind offshore rock breakwaters, 90 acres of reef creation and substrate improvement, 15 acres of creation and enhancement of tidal and non-tidal wetlands, and 30 acres of upland capping of contaminated soil. Design development concepts for these projects are presented along with reports on the completed construction that describe practical measures used to achieve the goals of the restoration. © 2013 American Society of Civil Engineers. Source

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