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Shen J.,Iowa State University | Akbas B.,Gebze Technical University | Seker O.,Iowa State University | Doran B.,Yildiz Technical University | And 2 more authors.
International Journal of Steel Structures | Year: 2015

During the 1994 Northridge Earthquake, many buildings with modern steel moment resisting frames (SMRFs) suffered from connection failures. One year later, similar damage has occurred in the 1995 Kobe earthquake in Japan. The unexpected seismic response of SMRFs resulted in comprehensive analytical and theoretical investigations and major changes in steel building design have been implemented consequently. One of the requirements in the subsequent seismic design codes is the stability check of the columns. Column yielding in a seismic force resisting systems (SFRSs) is not the desired damage mode and might result in column rupture or global buckling and threaten life safety. This study focuses on exploring the seismic axial loads for columns in SMRFs under strong ground motions. For this purpose, the increase in axial loads in low-, medium-, and high-rise SMRFs are investigated at the maximum lateral load level and the corresponding lateral displacement. The results are presented in terms of PHRs, average system overstrength factors (Ω0) of all columns in the frames under the selected ground motions, the distribution of Ω0 in the individual columns in the frame, and axial load levels in columns. The results indicate that axial load level remains below 0.4 in the columns for low- and medium-rise frames, whereas it may get as high as 0.95 in highrise frames. © 2015, Korean Society of Steel Construction and Springer-Verlag Berlin Heidelberg.


Uckan E.,Bogazici University | Akbas B.,Gebze Technical University | Shen J.,Iowa State University | Rou W.,Sharma & Associates Inc. | And 2 more authors.
Soil Dynamics and Earthquake Engineering | Year: 2015

The seismic response analysis of buried pipelines at fault crossings is a complex problem requiring nonlinear 3D soil-structure and large deformation analyses. Such analyses are computationally expensive and the results are hard to evaluate. Therefore, a simple numerical model is needed for engineering and design offices to determine the seismic demand of steel pipes at fault crossings. This paper presents a simplified numerical model for buried steel pipes crossing strike-slip faults and oriented perpendicular to the fault. Two pipes with different diameter to thickness (. D/. t) ratios and steel grades are used in the study. The proposed model permits plastic hinge formations in the pipe due to incrementally applied fault movements, allows determination of the critical length of the pipeline and measure strains developed on the tension and compression sides in the pipe. The model also considers the effect of bending as well as axial strains due to stretching. © 2015 Elsevier Ltd.


Rou W.,Sharma & Associates Inc. | Akbas B.,Gebze Technical University | Uckan E.,Istanbul University
Journal of Constructional Steel Research | Year: 2015

Abstract Inherent resistance to collapse has been observed in steel buildings with non-ductile concentrically braced frames (CBFs) during past major earthquakes. Understanding of the fundamental characteristics of near-collapse behavior of such buildings will help reveal seismic performance of non-ductile steel structures in existing buildings across the US, and lead to an efficient seismic retrofit of those in seismic zones. This paper presents a seismic evaluation of typical steel buildings using non-ductile CBFs as lateral load resisting structures with focus on their near-collapse behavior, based on the incremental dynamic analysis. The buildings with non-ductile CBFs were found to be fully operational up to 0.5% story drift ratio response with or without gravity frames participating in lateral-load-resisting system. However, the life safety and collapse prevention of the buildings were significantly improved by actually participating lateral-load-resisting systems including CBFs, steel gravity frames and concrete slabs. Furthermore, the post-damage response of the building was more significantly influenced by gravity frames as the damages progressed from its first brace fracture to near collapse, and the participation of the gravity frames had much more impact on the near collapse behavior of a taller building than that of a low-rise building. © 2015 Elsevier Ltd.


Martinez E.,LTK Engineering Services | Nelson F.,LTK Engineering Services | Prabhakaran A.,Sharma & Associates Inc. | Jones A.,Voith GmbH
Transportation Research Record | Year: 2012

An innovative rail car procurement specification was developed for bi-level equipment. This specification was developed to fulfill the Passenger Rail Investment and Improvement Act of 2008 (PRIIA). PRIIA is a congressional mandate to the National Railroad Passenger Corporation, state departments of transportation, FRA, and passenger rail car builders and suppliers to develop the next generation of passenger rail equipment for intercity corridor service for speeds up to 125 mph. Technological innovations are to be used to improve safety incrementally, and components are to be standardized to the extent possible to leverage economies of scale to help revitalize the manufacturing base for domestic passenger equipment. This paper focuses on the technical discussions held by a cross section of key industry stakeholders to develop specification language for crash energy management features as an overlay on a fully compliant bi-level car design. The purpose of the paper is to widely disseminate the methodology and process used and to provide background information on the values chosen for individual car crush zone performance.


Stewart M.F.,Federal Railroad Administration | Punwani S.K.,Federal Railroad Administration | Andersen D.R.,Sharma & Associates Inc. | Booth G.F.,Sharma & Associates Inc. | And 2 more authors.
2015 Joint Rail Conference, JRC 2015 | Year: 2015

Longitudinal dynamics influence several measures of train performance, including schedules and energy efficiency, stopping distances, run-in/run-out forces, etc. Therefore, an effective set of tools for studying longitudinal dynamics is essential to improving the safety and performance of train operations. Train Energy and Dynamics Simulator (TEDS) is a state-of-the-art software program designed and developed by the Federal Railroad Administration (FRA), for studying and simulating train safety and performance, and can be used for modeling train performance under a wide variety of equipment, track, and operating configurations [1]. Several case studies and real-world applications of TEDS, including the investigation of multiple train make-up and train handling related derailments, a study of train stopping distances, evaluations of the safety benefits of Electronically Controlled Pneumatic (ECP) brakes, Distributed Power operations, and a study of alternate train handling methodologies are described in this paper. These studies demonstrate the effectiveness of using the appropriate simulation tools to quantify and enhance a better understanding of train dynamics, and the resultant safety benefits. Copyright © 2015 by ASME.


Shurland M.,Federal Railroad Administration | Andersen D.R.,Sharma & Associates Inc. | Prabhakaran A.,Sharma & Associates Inc. | Singh S.P.,Sharma & Associates Inc.
2015 Joint Rail Conference, JRC 2015 | Year: 2015

This paper discusses the feasibility of shedding electrical demand associated with passenger coach HVAC systems during periods of peak traction needs, with the goal of rightsizing the main engine on a passenger locomotive, and possibly eliminating the HEP. In this study, train operation simulations were conducted to determine the sustained durations of peak traction needs on typical commuter and long distance routes. The simulation results were combined with thermal analyses of a sample passenger coach to investigate whether the required comfortable temperature range could be maintained for the durations of peak traction needs, with the HVAC system deactivated. Additionally, a review of available technology for load-shedding, and an economic analysis were conducted to evaluate the feasibility of implementing load shedding on passenger trains. The study showed that an appropriate load shedding strategy can be implemented without adversely impacting the industrywide passenger comfort standards and eliminating the capital and maintenance costs associated with an HEP. Copyright © 2015 by ASME.


Gonzalez F.,Federal Railroad Administration | Prabhakaran A.,Sharma & Associates Inc. | Booth G.F.,Sharma & Associates Inc. | Gantoi F.M.,Sharma & Associates Inc. | Vithani A.R.,Sharma & Associates Inc.
2015 Joint Rail Conference, JRC 2015 | Year: 2015

There is a significant increase in the transportation by rail of hazardous materials such as crude oil and ethanol in the North American market. Several derailment incidents associated with such transport have led to a renewed focus on improving the performance of tank cars against the potential for puncture under derailment conditions. Proposed strategies for improving puncture resistance have included design changes to tank cars, as well as, operational considerations such as reduced speeds. Given the chaotic nature of derailment events, it has been difficult to quantify globally, the overall 'real-world' safety improvement resulting from any given proposed change. A novel and objective methodology for quantifying and characterizing reductions in risk that result from changes to tank car designs or the tank car operating environment is outlined in this paper. The proposed methodology captures several parameters that are relevant to tank car derailment performance, including multiple derailment scenarios, derailment dynamics, impact load distributions, impactor sizes, operating conditions, tank car designs, etc., and combines them into a consistent probabilistic framework to estimate the relative merit of proposed mitigation strategies. Copyright © 2015 by ASME.


Grant
Agency: Department of Transportation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 149.41K | Year: 2015

This project seeks to define the performance requirements for a wireless Digital Train Line (WiDTL) through definition of functionality and performance expected, and translating these into network equipment specifications and architecture that wireless network equipment manufacturers can build towards. The effort will include an in-depth review of wireless technology as it applies to sensitive and vital communications, and also an evaluation of the commercial technology available to meet the needs outlined.


Grant
Agency: Department of Transportation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 149.71K | Year: 2015

Autorack cars transport one of the most valuable commodities – fully assembled Automobiles. Due to the longer and higher profile of an Autorack and the fact that heavy automobiles are loaded on to high deck levels, freight trucks with improved track-to-vehicle dynamics as well as higher speed capabilities are desired in anticipation of higher speed passenger service and shared corridors. Unique track-to-vehicle dynamics as well as space requirements create a unique challenge in designing improved freight truck designs for Autorack cars. The higher speed freight truck (HST) developed under FRA sponsorship holds promise for such application. SA will research current state-of-the-art truck designs and compare vehicle dynamics performance of the most prevelant design with those of the HST. SA will then develop a concept for the next generation freight truck for Autorack cars such that it meets desired dynamics as well as necessary clearance requirements..


Grant
Agency: Department of Transportation | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 149.44K | Year: 2012

Migration of the vehicle fleet from the current, pneumatic-only, automatic air brake (AAB) system to ECP presents a significant challenge due to the systems’ inherent operational incompatibility. This project will investigate the feasibility of devices that can help to ease this transition by allowing ECP equipped cars to operate in a conventionally braked train, as well as devices to permit conventional cars to operate in an ECP train. An emulator device, applied to a stand-alone ECP car, acts in conjunction with the car’s ECP components to emulate the functions of a conventional pneumatic control valve. The control valve emulator monitors local brake pipe pressure and interprets the pressure fluctuation signals to obtain brake application and release commands. These commands are then communicated to the ECP car control device (CCD) via the electrical train line using standard ECP train brake commands. The CCD functions in its normal manner to control brake cylinder pressure. The emulator also generates other messages required for proper operation of the CCD, such as the head end unit beacon. In addition, the emulator provides the control valve features that help to propagate pneumatic signals in the brake pipe, such as quick service, accelerated application, and accelerated release.

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