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Showing 14 results for Subject: Design

A. Kaveh, H.a. Rahimi Bondarabady, L. Shahryari,
Volume 4, Issue 3 (9-2006)
Abstract

The main aim of this paper is to extend the recently developed methods for calculating the buckling loads of planar symmetric frames to include the effect of semi-rigidity of the joints. This is achieved by decomposing a symmetric model into two submodels and then healing them in such a manner that the :::union::: of the eigenvalues of the healed submodels result in the eigenvalues of the entire model. Thus the critical load of the frame is obtained using the eigenvalues of its submodels.
T. Dahlberg,
Volume 8, Issue 1 (3-2010)
Abstract

The track stiffness experienced by a train will vary along the track. Sometimes the stiffness variation may be

very large within a short distance. One example is when an unsupported sleeper is hanging in the rail. Track stiffness

is then, locally at that sleeper, very low. At insulated joints the bending stiffness of the rail has a discontinuity implying

a discontinuity also of the track stiffness. A third example of an abrupt change of track stiffness is the transition from

an embankment to a bridge. At switches both mass and stiffness change rapidly. The variations of track stiffness will

induce variations in the wheel/rail contact force. This will intensify track degradation such as increased wear, fatigue,

track settlement due to permanent deformation of the ballast and the substructure, and so on. As soon as the track

geometry starts to deteriorate, the variations of the wheel/rail interaction forces will increase, and the track

deterioration rate increases. In the work reported here the possibility to smooth out track stiffness variations is

discussed. It is demonstrated that by modifying the stiffness variations along the track, for example by use of grouting

or under-sleeper pads, the variations of the wheel/rail contact force may be considerably reduced.


M. Saiidi, C. Cruz, D. Hillis,
Volume 8, Issue 1 (3-2010)
Abstract

Three unconventional details for plastic hinges of bridge columns subjected to seismic loads were developed,

designed, and implemented in a large-scale, four-span reinforced concrete bridge. Shape memory alloys (SMA),

special engineered cementitious composites (ECC), elastomeric pads embedded into columns, and post-tensioning

were used in three different piers. The bridge model was subjected to two-horizontal components of simulated

earthquake records of the 1994 Northridge earthquake in California. The multiple shake table system at the University

of Nevada, Reno was used for testing. Over 300 channels of data were collected. Test results showed the effectiveness

of post-tensioning and the innovative materials in reducing damage and permanent displacements. The damage was

minimal in plastic hinges with SMA/ECC and those with built in elastomeric pads. Conventional reinforced concrete

plastic hinges were severely damaged due to spalling of concrete and rupture of the longitudinal and transverse

reinforcement. Analytical studies showed close correlation between the results from the OpenSEES model and the

measured data for moderate and strong earthquakes.


I.a. Hansen,
Volume 8, Issue 1 (3-2010)
Abstract

The paper discusses the current state of research concerning railway network timetabling and traffic

management. Timetable effectiveness is governed by frequency, regularity, accurate running, recovery and layover

times, as well as minimal headway, buffer times and waiting times. Analytic (queuing) models and stochastic microsimulation

are predominantly used for estimation of waiting times and capacity consumption anlong corridors and in

stations, while combinatorial models and stability analysis are suitable for network timetable optimisation. Efficient

traffic management can be achieved by real-time monitoring, fusion, analysis and rescheduling of railway traffic in

case of disturbances. Real-time simulation, optimisation and impact evaluation of dispatching measures can improve

the effectiveness of rescheduling and traffic management. The display of dynamic signal and track occupancy data in

driver cabins, as RouteLint developed by ProRail, can support anticipative actions of the driver in order to reduce

knock-on delays and increase throughput.


F. Messaoud, M. S. Nouaouria,
Volume 8, Issue 1 (3-2010)
Abstract

This paper presents a description of the equipment, testing procedure, and methodology to obtain ground

mechanical parameters. The p-y curves for laterally loaded piles are developed. Methods for the development of p-y

curves from pressure meter and dilatometer (DMT) test are described. P-y curves are used in the analysis to represent

lateral soil-pile interaction. The pressure meter offers an almost ideal in-situ modeling tool for determining directly

the p-y curves for the design of deep foundations. As the pressure meter can be driven into the soil, the results can be

used to model a displacement pile. DMT tests were performed for comparisons with PPMT tests. Correlations were

developed between the PPMT and DMT results, indicating a consistency in soil parameters values. Comparisons

between PPMT and DMT p-y curves were developed based on the ultimate soil resistance, the slope of the initial

portion of the curves, and the shape of the curves. The initial slope shows a good agreement between PPMT and DMT

results. The predicted DMT and PPMT ultimate loads are not similar, while the predicted PPMT and DMT deflections

within the elastic range are identical.


J. Sadeghi, P. Barati,
Volume 8, Issue 1 (3-2010)
Abstract

Current practices in railway track analysis and design are reviewed and discussed in this paper. The

mechanical behavior of railway track structure comprising of various components has not been fully understood due

to the railway track structural complexity. Although there have been some improvements in the accuracy of current

track design methods in recent decades, there are still considerable uncertainties concerning the accuracy and

reliability of the current methods. This indicates a need for a thorough review and discussion on the current practices

in the analysis and design of railway track systems. In this paper, railway design approaches proposed by various

standards along with the results of a wide range of technical researches are studied and necessary suggestions are

made for the improvement of current practices in the analysis and design of railway track


N. Adamko, V. Klima, P. Marton,
Volume 8, Issue 1 (3-2010)
Abstract

Railway service terminals are the places of a railway network usually equipped with costly technology based

on highly complicated technological procedures demanding a high degree of coordination and control skills. Design

of these systems and the organization of their operation should facilitate reaching to the required capacity together

with high quality of service processes as well as minimal costs of resources. Due to the complexity of such systems, a

simulation model seems to be the only suitable tool for performing investigations under realistic conditions. The paper

focuses on the possible utilization of simulation methods to support the design and optimisation of infrastructure,

operation, and process control algorithms in railway terminals. The paper also deals with the most important

properties and possibilities offered by the simulation tool Villon and comments on the experience gained during its

utilization. The tool supports tactical (mid-term) and strategic (long-term) planning usually related to infrastructural

or operational proposals which are supposed to guarantee the optimal (or at least effective) behaviour of the modelled

terminal.


H.m. Noh, Y.o. Cho,
Volume 8, Issue 1 (3-2010)
Abstract

In this paper, the processes which are currently under development in South Korea, concerning railway

safety management system are introduced. Railway safety management system in South Korea is briefly presented,

making particular attentions to Systems Engineering Management Plan (SEMP). To make huge national R&D projects

successful, systematic management process is essential. In this respect, detailed applying SEMP on railway safety

management system of South Korea is discussed including Systems Engineering process and Verification and

Validation procedures. Furthermore, a computer-aided systems engineering tool (Cradle) is used in order to make the

management process more easily controllable.


M. Ameri, J. Shahi, H. Khani Sanij,
Volume 11, Issue 1 (3-2013)
Abstract

The use of geotextiles to postpone reflective cracks in asphalt overlay is a popular practice, so researchers are eager to calculate its structural value. This research study has focused on this issue for geotextiles used in the roads of Iran. Twelve sections from the Tehran-Qom road were tested each examined before and after construction of the overlay. The tests were of the Falling Weight Deflectometer type, and at least twelve tests were conducted each time. The data from five sections (four for developing the model and one for evaluating the output) allowed a new mathematical model to be developed. For the seven remaining sections, some foreign and Iranian geotextiles were used as interlayers. The mean structural value for all of the geotextiles was equivalent to that of a 2.92 cm-thick Hot Mix Asphalt overlay, while that for only the Iranian sections was equivalent to 2.28 cm. Economic evaluations, based on construction costs, showed that in 2011 the use of geotextiles was economical in Iran, because fuel and bitumen subsidies had been eliminated and different geotextile brands had been brought to market in the country.
Kaustav Bakshi, Dipankar Chakravorty,
Volume 12, Issue 2 (6-2014)
Abstract

A review of literature reveals that although singly curved conical shells applicable in many fields of mechanical engineering have been studied by many researchers but doubly curved conoidal shells which are very popular as civil engineering roofing units have not received due attention. Hence relative performances of composite conoidal shells in terms of displacements and stress resultants are studied in this paper under static and dynamic loadings. Free vibration frequencies are also reported. A curved quadratic isoparametric eight noded element is used to model the shell surface. Clamped and simply supported boundary conditions are considered. Results obtained from the present study are compared with established ones to check the correctness of the present approach. A number of additional problems of composite conoidal shells are solved for eight different stacking sequences of graphite-epoxy composite for each of the edge conditions. Uniformly distributed load for static bending analysis and step load of infinite duration for solution of forced vibration problem are considered. The results are interpreted from practical application standpoints and findings that are important for a designer to note, before he decides on the shell combination he will finally adopt among a number of possible options, are highlighted.
Fabrizio Palmisano, Angelo Elia,
Volume 12, Issue 2 (6-2014)
Abstract

The increase in the computational capabilities in the last decade has allowed numerical models to be widely used in the analysis, leading to a higher complexity in structural engineering. This is why simple models are nowadays essential because they provide easy and accessible understanding of fundamental aspects of the structural response. Accordingly, this article aims at showing the utility and effectiveness of a simple method (i.e. the Load Path Method) in the interpretation of the behaviour of masonry buildings subjected to foundation settlements due to landslide. Models useful for understanding brick-mortar interface behaviour as well as the global one are reported. The global proposed approach is also validated by using Bi-directional Evolutionary Structural Optimization method. Moreover, drawing inspiration from a case study, the article shows that the proposed approach is useful for the diagnosis of crack patterns of masonry structures subjected to landslide movements.
E. Kozem Šilih, M. Premrov, M. Kuhta, S. Šilih,
Volume 13, Issue 4 (12-2015)
Abstract

The paper presents a parametric numerical study on the horizontal load-bearing capacitiy of timber framed wall elements coated with single fibre plaster boards (FPB) that can be used in the construction of single- or multi-storey prefabricated buildings. The research deals with both the full elements (without any opening) and with elements containing an opening. The key behaviour indicators like the racking stiffness and strength were determined and presented as ratios dependent on the opening area. A comparative study has proved that none of the methods from the literature that were previously developed for different types of wall elements can be accurately applied to the FPB-sheated panels. It has also been shown that the methods currently available in the European design codes underestimate the capacity of wall elements with openings. Based on the results some diagrams are proposed that enable quick and efficient determination of the essential properties of wall elements with arbitrary areas of openings and may thus represent a useful tool for the structural design process.


Maria Castro, Rafael Luque,
Volume 14, Issue 6 (9-2016)
Abstract

The geometric design of a road based on consistency implies that this should not violate driver expectations. Although there are different methods for estimating consistency, the most used have been those based on the operating speed of vehicles. This is due to its relationship with accidents. Road alignments which cause marked differences in vehicle speeds favour a greater accident rate. In this research local approaches to evaluate the consistency of the alignments (tangents, curves) versus global approaches to evaluate an entire stretch of road have been analyzed. Different models have been used to estimate operating speed of vehicles. The study has focused from a practical point of view using two applications for the evaluation of consistency of a stretch of road. The results show the influence of the choice of the speed model in the level of consistency. In addition, practical issues about how some variables, such as desired speed, posted speed and design speed, can influence the results are presented.


Varol Koç, Yusuf Emiroğlu,
Volume 15, Issue 7 (10-2017)
Abstract

Minimum reinforcement ratios provided in the standards are remaining at very low levels especially at large systems subject to the effects of earthquake. Thus, arranging the reinforcement ratios intended for preliminary design can provide significant ease and safety in project design phase, and speed and simplicity in the project control phase. Moreover, a more realistic limitation becomes ensured compared to general minimum reinforcement ratios given in the standards. System characteristics which may affect the reinforcement ratios can be specified by general and simple parameters. As the result of many extensive studies, expressions for reinforcement ratios intended for preliminary design which will cover systems having different parameters can be composed. Today, thanks to the development levels of finite elements programs which can perform reinforced concrete modeling, meeting this requirement is much more possible compared to the past. Structure of parameters should neither be very special nor very general. Otherwise, reinforcement ratios intended for preliminary design will either be valid for a single system or they will remain at very low limits such as the minimum reinforcement ratios given in the standards. For this reason, in this study it was tried to follow a route in between these two extreme conditions. Today, it is possible to perform many studies on the systems having different and comprehensive inclusive parameters and to determine practical ratios which will constitute a recommendation for the project designs. For this purpose, an eight storey reinforced concrete system with single spacing whose shear wall cross-section is 25x250cm, column cross-section is 25x30cm, and beam cross-section is 25x50cm was addressed, and its non-linear planary analyses under static earthquake loads were performed through the ANSYS finite elements program for 13 different reinforcement case. The reinforcement ratios to be recommended for the addresses system and similar systems were tried to be revealed. The examined system was arranged as to get the most critical and extreme values for many parameters which can be considered, but it was tried for the reinforcement ratios to be recommended to be valid not only for this system but also for the general system network having similar properties to this system. In the future researches, expressions of general and inclusive preliminary design reinforcement ratios can be obtained as per the results of many studies to be made on systems having different parameters.



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