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Structural Engineering

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Selected Works

Articles 31 - 41 of 41

Full-Text Articles in Civil and Environmental Engineering

Simulating Gpr For Diagnosis Of Civil Infrastructure, Laura Carey, Kimberly Belli, Carey M. Rappaport, Sara J. Wadia-Fascetti Apr 2012

Simulating Gpr For Diagnosis Of Civil Infrastructure, Laura Carey, Kimberly Belli, Carey M. Rappaport, Sara J. Wadia-Fascetti

Carey Rappaport

At the present, a large proportion of our nation's bridges and roadways are falling into disrepair. About 27.5% of U.S. bridges are structurally deficient or functionally obsolete (ASCE, 2001, 2003). Nondestructive testing methods, such as GPR, are becoming more and more important in diagnosing the condition of such concrete structures. GPR is a high-resolution electromagnetic technique used to investigate the immediate subsurface of the earth, building materials, roads, and bridges. This poster shows my work in GPR modeling during a summer undergraduate experience through CenSSIS. A specialized MATLAB toolbox designed by Kim Belli created all data presented here. The use …

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State Dependent Properties Of Rail Pads, Sakdirat Kaewunruen, Alexander Remennikov Nov 2011

State Dependent Properties Of Rail Pads, Sakdirat Kaewunruen, Alexander Remennikov

Alex Remennikov

Rail pad is one of the main components in ballasted railway track systems. It is inserted between the rail and the sleeper to attenuate dynamic wheel/rail interaction forces, preventing the underlying railway track components from excessive stresses. Generally, the dynamic design of tracks relies on the available data, which are mostly focused on the structural condition at a specific toe load. Recent findings show that track irregularities could significantly amplify the loads on railway tracks. This phenomenon gives rise to a concern that the rail pads may experience higher deterioration rate than anticipated in the past. On this ground, an …

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Relationship Between Impact Energy And Fracture Toughness Of Prestressed Concrete Railway Sleepers, Sakdirat Kaewunruen, Alexander Remennikov Nov 2011

Relationship Between Impact Energy And Fracture Toughness Of Prestressed Concrete Railway Sleepers, Sakdirat Kaewunruen, Alexander Remennikov

Alex Remennikov

The prestressed concrete sleepers (or railroad ties), which are installed in railway track systems as the crosstie beam support, are designed to carry and transfer the wheel loads from the rails to the ground. It is well known that railway tracks are subject to impact loading conditions, which are attributable to the train operations with either wheel or rail abnormalities such as flat wheels, dipped rails, etc. These loads are of very high magnitude but short duration. In addition, there exists the potential of repeated load experience during the design life of prestressed concrete sleepers. Prestressed concrete has played a …

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Dynamic Design Guidelines For Prestressed Concrete Sleepers, Alexander Remennikov, Martin H. Murray, Sakdirat Kaewunruen Nov 2011

Dynamic Design Guidelines For Prestressed Concrete Sleepers, Alexander Remennikov, Martin H. Murray, Sakdirat Kaewunruen

Alex Remennikov

Current design philosophy, outlined in AS 1085.14, is based on the analysis of permissible stresses resulting from quasi-static wheel loads and essentially the static response of concrete sleepers. In general, cracking can incur when the bottom fibre stress is larger than tensile strength of concrete. Premature cracking of prestressed concrete sleepers has been detected in railway tracks. The major cause of cracking is the infrequent but high-magnitude wheel loads produced by a small percentage of “out-of-round” wheels or railhead surface defects, which are crudely accounted for in AS 1085.14 by a single load factor. Based on the current design method, …

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Dynamic Properties Of Railway Track And Its Components : A State-Of-The-Art Review, Sakdirat Kaewunruen, Alexander Remennikov Nov 2011

Dynamic Properties Of Railway Track And Its Components : A State-Of-The-Art Review, Sakdirat Kaewunruen, Alexander Remennikov

Alex Remennikov

Recent findings indicate one of major causes of damages, which is attributed to the resonant behaviours, in a railway track and its components. Basically, when a railway track is excited to generalised dynamic loading, the railway track deforms and then vibrates for certain duration. Dynamic responses of the railway track and its components are the key to evaluate the structural capacity of railway track and its components. If a dynamic loading resonates the railway track’s dynamic responses, its components tend to have the significant damage from excessive dynamic stresses. For example, a rail vibration could lead to defects in rails …

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The Homotopy Perturbation Method For Free Vibration Analysis Of Beam On Elastic Foundation, Baki Ozturk, Safa Bozkurt Coskun Dec 2010

The Homotopy Perturbation Method For Free Vibration Analysis Of Beam On Elastic Foundation, Baki Ozturk, Safa Bozkurt Coskun

Safa Bozkurt Coskun

In this study, the homotopy perturbation method (HPM) is applied to free vibration analysis of beam on elastic foundation. This numerical method is applied on three different axially loaded cases, namely: 1) one end fixed, the other end simply supported; 2) both ends fixed and 3) both ends simply supported cases. Analytical solutions and frequency factors are evaluated for different ratios of axial load N acting on the beam to Euler buckling load, Nr. The application of HPM for the particular problem in this study gives results which are in excellent agreement with both analytical solutions and the variational iteration …

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Nonlinear Finite Element Analysis Of Prestressed Concrete, Akram Shaker Mahmood, Mohamed N. Mahmood Aug 2010

Nonlinear Finite Element Analysis Of Prestressed Concrete, Akram Shaker Mahmood, Mohamed N. Mahmood

Akram Shaker Mahmood

In the present study a nonlinear finite element analysis is carried out on twenty prestressed concrete cantilever beams having different lengths vary from 1.0m to 3.0m with 0.5m increments and subjected to a concentrated torque at the free end using ANSYS V10 finite element package. This study emphasizes on the effect of beam length to depth ratio on the strength, behavior of prestressed concrete beams and effectiveness of prestressing strands in the pre and post cracking stages of loading. This work is part of a PhD research program at the University of Mosul to investigate the non-linear three dimensional behavior …

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Reliability Assessment Of Railway Prestressed Concrete Sleepers, Sakdirat Kaewunruen, Alexander Remennikov Jan 2009

Reliability Assessment Of Railway Prestressed Concrete Sleepers, Sakdirat Kaewunruen, Alexander Remennikov

Alex Remennikov

This paper carries out the assessment of reliability indices of railway prestressed concrete sleepers designed in accordance with Australian Standard: AS1085.19. The current design approach of the prestressed concrete sleeper relies on the permissible stresses over crosssectional area. Loading condition acting on railway sleepers is considered from axle burden and dynamic amplification factor. On the basis of Australian design of railway prestressed concrete sleepers, only service limit states are considered; however, the design challenge is to provide adequate resistance of certain cross sections to both positive and negative bending moments. In this paper, the service limit states functions are formulated …

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Impact Damage Classification Of Railway Prestressed Concrete Sleepers, Sakdirat Kaewunruen, Alexander Remennikov Jan 2009

Impact Damage Classification Of Railway Prestressed Concrete Sleepers, Sakdirat Kaewunruen, Alexander Remennikov

Alex Remennikov

Commonly, railway tracks suffer with the extreme loading conditions, which are attributed to the train operations with either wheel or rail abnormalities such as flat wheels, dipped rails, etc. These loads are of very high magnitude but short duration, as well as they are of low-possibility occurrence during the design life of the prestressed concrete sleepers. In spite of the most common use of the prestressed concrete sleepers in railway tracks, their impact responses and behaviours are not deeply appreciated nor taken into the design consideration. Up until recently, a new limit states design approach, whereas the dynamic effects are …

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An Assessment Of The Use Of Structural Deformation As A Method Of Determining Area Of Fire Origin, Andrew Tinsley, David Icove Dec 2007

An Assessment Of The Use Of Structural Deformation As A Method Of Determining Area Of Fire Origin, Andrew Tinsley, David Icove

Andrew T Tinsley

Current methodologies of origin investigation have yet to include the structural deformations seen in steel buildings as a viable indicator of the area of origin of a given fire. As many steel structures are of relatively large size, it is often difficult to determine the area of origin using the typical dig and sift methods advocated in NFPA 921, especially if the extent of the fire was large and there were no witnesses as to the origin of the fire. As has been investigated for years, the performance of steel is highly affected by the application of heat. The science …

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Design And Characteristics Of A Split Hopkinson Pressure Bar Apparatus, Radek Glaser, Jesse Haines, Christopher Knight May 2007

Design And Characteristics Of A Split Hopkinson Pressure Bar Apparatus, Radek Glaser, Jesse Haines, Christopher Knight

Radek Glaser

A Split Hopkinson Pressure Bar Apparatus, also known as Kolsky Bar that is capable of conducting compressive strain rate testing in the approximate ranges from 50 to 10^4 in/in per second was designed as a part of a Senior Design Project. Generally, this device is similar to that first used by Kolsky in 1949. The design of this device is presented here in two stages: 1. Research, design and manufacturing of the Stress Generating System 2. Experimental Part – Testing of the apparatus to obtain necessary data. The present phase of the design was focused mostly on the stress generating …

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