Excellence in Research and Innovation for Humanity

International Science Index

Commenced in January 1999 Frequency: Monthly Edition: International Abstract Count: 39602

Civil and Environmental Engineering

1582
67093
Field Investigating the Effects of Lateral Support Elements on Lateral Resistance of Ballasted Tracks with Sharp Curves
Abstract:
Lateral movement of CWR ballasted track occurs in sharp curves because of the lack of adequate lateral resistance. Several strategies have been proposed and used for increase the lateral resistance of ballasted tracks, but still there are some problems in tracks with small radius curves. In this paper, a new method has been presented for increase the lateral resistance. This method is using the lateral supports as numerical and field studies. In this paper, the field and laboratory tests have been conducted by using the single tie pressure test (STPT) and track panel loading test (LTPT). Then, their results were compared with the numerical results. The results of numerical and field tests showed that the lateral stiffness of ballasted tracks significantly increased when there were lateral supports in ballasted tracks. Also, the track structure had a bilinear behavior.
1581
67064
Development of a Testing Rig for a Cold Formed-Hot Rolled Steel Hybrid Wall Panel System
Abstract:
The new concept of a cold formed-hot rolled hybrid steel wall panel system is introduced to overcome the deficiency in lateral load resisting capacity of cold-formed steel structures. The hybrid system is composed of a cold-formed steel part laterally connected to hot rolled part. The hot rolled steel part is responsible for carrying the whole lateral load; while the cold formed steel part is only required to transfer the lateral load to the hot rolled part without any local failure. The vertical load is beared by both hot rolled, and cold formed steel part, proportionally. In order to investigate the lateral performance of the proposed system, it should be tested under simultaneous lateral and vertical load. The main concern is to deliver the loads to each part during the test to simulate the real load distribution in the structure. In this paper, a detailed description of the proposed wall panel system and the designed testing rig is provided.
1580
67050
Parametric Study of Fly Ash Based Geopolymer Concrete
Abstract:
With the growth of civilization, the demand of cement concrete is increasing rapidly which increases the production of cement and abolishing the natural source of limestone. Also contributing a lot to the global warming by generating huge amount of carbon-di-oxide. Therefore the present study concentrates on the production of concrete using the geopolymerization technology which replaces cement fully by fly ash, a waste material, and alkali solution. India is presently producing approximately 190 million tons of fly ash every year from moreover 145 power plants. In the present research different parameters such as curing temperature, curing type, ratio of sodium silicate to sodium hydroxide, the molarity of sodium hydroxide have been studied and discussed. Previous works emphasis that only the use of fly ash as the base material confine the concrete to be heat cured which limits the applicability of geopolymer concrete to cast-in-situ conditions. So some proportion of Flyash is replaced by ground granulated blast furnace slag (GGBFS) and the effect on compressive and tensile strength is observed. Ambient temperature curing was done without any water when some proportion of fly ash was replaced by GGBFS. The ratio of sodium silicate solution to sodium hydroxide solution by mass was kept fixed at 2.5, and the concentration of sodium hydroxide was kept 14M. The ratio of fly ash to alkali solution was kept 0.35 & 0.40. With a replacement of 40% of Fly ash by GGBFS and keeping the concentration of NaOH as 14M at ambient temperature the compressive strength encountered was 40 MPa.
1579
66965
Dynamic Modeling of Transition Zones
Abstract:
In railways transition zone is present at the boundaries of zones with different stiffness. When a train rides from an embankment onto a stiff structure, such as a bridge, tunnel or culvert, an abrupt change in the support stiffness occurs possibly inducing differential settlements. This in long term can yield to the degradation of the tracks and foundations in the transition zones. A number of techniques have been proposed or implemented to provide gradual stiffness transition at the problem zones, such as methods to ensure gradually changing pad stiffness, application of long sleepers or installation of auxiliary rails in the transition zone. The problems associated with the transition zones require a complex analysis. For efficient modeling of the mechanisms resulting in gradual line deteriorations in the transition zones the understanding of the 3D and dynamic effects associated with the problem and also seems to be essential. To enhance our understanding of problem a 3D numerical model has been developed for time domain analysis. Aim of the research presented in this paper is to analyze the 3D and the dynamic effects induced by the passing train over an area where significant difference in the support stiffness exists. The effects were analyzed for different arrangements associated with certain differential settlement mitigation strategies of the transition zones. The authors also provide some outlook regarding the long-term behavior of the track at the culvert transition zone for high repetition number traffic loads considering the plastic accumulation of small strains and the resulting positive feedback effect.
1578
66953
Nonlinear Finite Element Analysis of Concrete Filled Steel I-Girder Bridge
Abstract:
Concrete filled steel I-girder (CFIG) bridge was proposed and the bending and shear strength was confirmed by experiments. The area surrounded by the upper and lower flanges and the web is filled with concrete in CFIG, which is used to the intermediate support of a continuous girder. Three-dimensional finite element models were established to simulate the bending and shear behaviors of CFIG and to clarify the load transfer mechanism. Steel plates and filled concrete were modeled as a three-dimensional 8-node solid element and steel reinforcement bars as a three-dimensional 2-node truss element. The elements were mostly divided into the 50 x 50 mm mesh size. The non-linear stress-strain relation is assumed for concrete in compression including the softening effect after the peak, and the stress increases linearly for concrete in tension until concrete cracking but then decreases due to tension stiffening effect. The stress-strain relation for steel plates was tri-linear and that for reinforcements was bi-linear. The concrete and the steel plates were rigidly connected. The developed FEM model was applied to simulate and analysis the bending behaviors of the CFIG specimens. The vertical displacements and the strains of steel plates and the filled concrete obtained by FEM agreed very well with the test results until the yield load. The specimens collapsed when the upper flange buckled or the concrete spalled off. These phenomena cannot be properly analyzed by FEM, which produces a small discrepancy at the ultimate states. The FEM model was also applied to simulate and analysis the shear tests of the CFIG specimens. The vertical displacements and strains of steel and concrete calculated by FEM model agreed well with the test results. A truss action was confirmed by the FEM and the experiment, clarifying that shear forces were mainly resisted by the tension strut of the steel plate and the compression strut of the filled concrete acting in the diagonal direction. A trail design with the CFIG was carried out for a four-span continuous highway bridge and the design method was established. Construction cost was estimated about 12% lower than that of a conventional steel I-section girder.
1577
66951
Integrating System-Level Infrastructure Resilience and Sustainability Based on Fractal: Perspectives and Review
Abstract:
Urban infrastructures refer to the fundamental facilities and systems that serve cities. Due to the global climate change and human activities in recent years, many urban areas around the world are facing enormous challenges from natural and man-made disasters, like flood, earthquake and terrorist attack. For this reason, urban resilience to disasters has attracted increasing attention from researchers and practitioners. Given the complexity of infrastructure systems and the uncertainty of disasters, this paper suggests that studies of resilience could focus on urban functional sustainability (in social, economic and environmental dimensions) supported by infrastructure systems under disturbance. It is supposed that urban infrastructure systems with high resilience should be able to reconfigure themselves without significant declines in critical functions (services), such as primary productivity, hydrological cycles, social relations and economic prosperity. Despite that some methods have been developed to integrate the resilience and sustainability of individual infrastructure components, more work is needed to enable system-level integration. This research presents a conceptual analysis framework for integrating resilience and sustainability based on fractal theory. It is believed that the ability of an ecological system to maintain structure and function in face of disturbance and to reorganize following disturbance-driven change is largely dependent on its self-similar and hierarchical fractal structure, in which cross-scale resilience is produced by the replication of ecosystem processes dominating at different levels. Urban infrastructure systems are analogous to ecological systems because they are interconnected, complex and adaptive, are comprised of interconnected components, and exhibit characteristic scaling properties. Therefore, analyzing resilience of ecological system provides a better understanding about the dynamics and interactions of infrastructure systems. This paper discusses fractal characteristics of ecosystem resilience, reviews literature related to system-level infrastructure resilience, identifies resilience criteria associated with sustainability dimensions, and develops a conceptual analysis framework. Exploration of the relevance of identified criteria to fractal characteristics reveals that there is a great potential to analyze infrastructure systems based on fractal. In the conceptual analysis framework, it is proposed that in order to be resilient, urban infrastructure system needs to be capable of “maintaining” and “reorganizing” multi-scale critical functions under disasters. Finally, the paper identifies areas where further research efforts are needed.
1576
66784
Free Shape Optimisation of Cold Formed Steel Sections
Abstract:
Cold-formed steel sections are popular construction materials as structural or non-structural elements. The objective of this paper is to propose an optimisation method for open cross sections targeting the maximum nominal axial strength. The cross sections considered in the optimisation process should all meet a determined critical global buckling load to be considered as a candidate for optimisation process. The maximum dimensions of the cross section are fixed and limited into a predefined rectangular area. The optimisation process is repeated for different available coil thicknesses of 1 mm, 2.5 mm and 3 mm to determine the optimum thickness according to the cross section buckling behaviour. A simple-simple boundary is assumed as end conditions. The number of folds is limited to 20 folds to prevent extra complicated sections. The global buckling load is considered as Euler load and is determined according to the moment of inertia of the cross-section with a constant length. The critical buckling loads are obtained using Finite Strip Method. The results of the optimisation analysis are provided, and the optimum cross-section within the considered range is determined.
1575
66756
Analysis of Dynamic Behavior and Resisting Capacity of RC Column Subjected to Blast Loading
Abstract:
This paper attempts to introduce a numerical method to simulate the dynamic nonlinear behavior of RC columns subjected to blast loading. In advance, a dynamic increase factor (DIF), which is usually defined in the stress-strain relationship of concrete and steel, is newly constructed on the basis of the moment-curvature relationship of an RC section. The moment-curvature relationship is modified in the critical regions such as the mid-span or beam-column joint in which the large plastic deformation probably occur due to bond slip after yielding of the reinforcing steel accompanying fixed-end rotation. Finally, the proposed method is verified through the correlation with the experimental data. In addition, the P-I diagram is estimated depending on the variation of the axial force.
1574
66490
Engineering Practice in Nigerian University: A Microcosm of Engineering Development and Practice in Developing Countries
Abstract:
There is a strong link between engineering and development. Engineering as a profession is a call to service by the society. Perhaps next to soldiers, engineers are the most patriotic professionals. However, unlike soldiers, they remain servants of society at all times and in all circumstances. Despite their role to the society, engineering profession seems not to be enjoying the respect due to it probably because of failures associated with some engineering projects. This paper focuses on the need to improve on engineering practices for developments in developing countries using Engineering practice in Nigerian Universities as a tool for argument. Purposeful Survey, interview and focus group discussion were carried out among one hundred and twenty (120) reputable firms in Nigeria. The topic was approached through a few projects that the firms have been involved in from the planning stage, some to completion and beyond into the stage of maintenance and monitoring. It is revealed that some factors which are not determined by the engineers themselves impeded progress and full success of engineering practice in developing countries. The key culprit is corruption whose eradication will put the nation on the solid path of effective engineering development and poverty alleviation.
1573
66488
Water Supply Scheme: Panacea to Development Using University of Ibadan as Case Study
Abstract:
The supply of potable water at least is a very important index in national development. Water tariff depends on the treatment cost which carries the highest percentage of the total operation cost in any water supply scheme. In order to keep water tariff as low as possible, treatment cost which carries the highest percentage of the total operating cost has to be minimized. The University of Ibadan water supply scheme consists of a treatment plant with three distribution stations (Amina way, Kurumi and Lander) and two raw water supply sources (Awba dam and Eleyele dam). Operational study of the scheme was carried out to ascertain efficiency of the supply of potable water on the campus to justify the need for water supply scheme in tertiary institutions. The study involved regular collection, processing and analysis of periodic operational data. Data collected include supply reading (water production on daily basis) and consumers metered reading for a period of twenty two months (October, 2013 - July 2015) also collected were the operating hours of both plants and human beings. Applying the required mathematical equations, total loss was determined for the distribution system and was translated into monetary terms. Adequacies of the operational functions were also determined. The study revealed that water supply scheme is justified in tertiary schools. It was also found out that about N 10,738,051.2 is lost to leakages within twenty two (22) months, the system’s storage capacity is no longer adequate especially for peak water production. The capacity of the system as a whole is insufficient for the present university population and that the existing water supply system is not being operated in an optimal manner especially due to personnel, power and system ageing constraints.
1572
66473
The Effect of an Infill on the Bearing Capacity and Stiffness of Infilled Frames
Abstract:
The application of frames with masonry or panel infill is common in the engineering practice. In these cases, a frame is often considered to be a primary structure, while an infill is considered to be a secondary structure. In past calculations, the infill was rarely included in the design of frame structures in terms of their bearing capacity and safety. Recent calculations of such structures necessarily include the effect of infill since it contributes to stiffness and bearing capacity of overall system, especially under horizontal loads. In certain cases, if the infill is not included in the seismic design of frame structures, the result can be lower design safety. However, since the different configuration of the infill through the building’s height can be made, it is possible that contribution of such infill to the overall bearing capacity can be lower and seismic forces on the building can be increased due to greater stiffness of the structure. So far, many experimental and numerical researches on the behavior of infilled frames under horizontal static forces and earthquake have been performed. In this paper, several masonry-infilled concrete and steel frames under horizontal static forces and earthquake are analysed. The experimental results by shake-table and numerical results are compared in terms of the bearing capacity of bare and infilled frames. Herein, the stiffness of frames and infill were varied, with different position of the infill and different types of openings. Cases with positive and negative effects of the infill to the bearing capacity of the frames were considered. Finally, main conclusions and recommendations for practical application and design of masonry-infilled concrete and steel frames are given.
1571
66464
Experimental Investigation to Produce an Optimum Mix Ratio of Micro-Concrete
Abstract:
Concrete is one of the basic elements of RCC structure and also the most crucial one. In recent years, a lot of researches have been conducted to develop special types of concrete for special purposes. Micro-concrete is one of them which has high compressive strength and is mainly used for retrofitting. Micro-concrete is a cementitious based composition formulated for use in repairs of areas where the concrete is damaged & the area is confined in movement making the placement of conventional concrete difficult. According to recent statistics, a large number of structures in the major cities of Bangladesh are vulnerable to collapse. Retrofitting may thus be required for a sustainable solution, and for this purpose, the utilization of micro-concrete can be considered as the most effective solution. For that reason, the aim of this study was to produce micro-concrete using indigenous materials in low cost. Following this aim, the experimental data were observed for five mix ratios with varied amount of cement, fine aggregate, coarse aggregate, water, and admixture. The investigation criteria were a compressive strength, tensile strength, slump and the cost of different mix ratios. Finally, for a mix ratio of 1:1:1.5, the compressive strength was achieved as 7820 psi indicating highest strength among all the samples with the reasonable tensile strength of 1215 psi. The slump of 6.9 inches was also found for this specimen indicating it’s high flowability and making it’s convenient to use as micro-concrete. Moreover, comparing with the cost of foreign products of micro-concrete, it was observed that foreign products were almost four to five times costlier than this local product.
1570
66460
Experimental Investigation on Performance of Beam Column Frames with Column Kickers
Abstract:
The worldwide use of reinforced concrete construction stems from the wide availability of reinforcing steel as well as concrete ingredients. However, concrete construction requires a certain level of technology, expertise, and workmanship, particularly, in the field during construction. As a supporting technology for a concrete column or wall construction, kicker is cast as part of the slab or foundation to provide a convenient starting point for a wall or column ensuring integrity at this important junction. For that reason, a comprehensive study was carried out here to investigate the behavior of reinforced concrete frame with different kicker parameters. To achieve this objective, six half-scale specimens of portal reinforced concrete frame with kickers and one portal frame without kicker were constructed according to common practice in the industry and subjected to cyclic incremental horizontal loading with sustained gravity load. In this study, the experimental data, obtained in four deflections controlled cycle, were used to evaluate the behavior of kickers. Load-displacement characteristics were obtained; maximum loads and deflections were measured and assessed. Finally, the test results of frames constructed with three different types of kicker thickness were compared with the kickerless frame. Similar crack patterns were observed for all the specimens. From this investigation, specimens with kicker thickness 3″ were shown better results than specimens with kicker thickness 1.5″, which was specified by maximum load, stiffness, initiation of first crack and residual displacement. Despite of better performance, it could not be firmly concluded that 4.5″ kicker thickness is the most appropriate one. Because, during the test of that specimen, separation of dial gauge was needed. Finally, comparing with kickerless specimen, it was observed that performance of kickerless specimen was relatively better than kicker specimens.
1569
66352
Global Buckling Behaviour of Welded Q460GJ Steel Box Columns: Experimental Study and Numerical Simulations
Abstract:
To date, high-performance structural steel has been widely used for columns in construction practices due to its significant advantages over conventional steel. However, the same design approach with conventional steel columns is still adopted in the design of high-performance steel columns. As a result, its superior properties cannot be fully considered in design. This paper describes an experimental and numerical study on the global buckling behaviour of welded Q460GJ steel box columns. In the experimental programme, four steel columns with different cross sections and wall thicknesses were tested under axial compression. Comparisons were made between experimental results and design values calculated in accordance with national standards. Furthermore, numerical models were established in which material nonlinearity and residual stress distributions were considered. The model was validated against test data with reasonably good accuracy. Experimental and numerical results indicate that Q460GJ steel box columns could develop higher global buckling resistances than the values calculated from different standards. Therefore, it is necessary to modify the design approaches for conventional steel columns so that the buckling behaviour of box columns fabricated of Q460GJ steel can be accurately evaluated.
1568
66349
Lateral Torsional Buckling Investigation on Welded Q460GJ Structural Steel Unrestrained Beams under a Point Load
Abstract:
This study aims to investigate the lateral torsional buckling of I-shaped cross-section beams fabricated from Q460GJ structural steel plates. Both experimental and numerical simulation results are presented in this paper. A total of eight specimens were tested under a three-point bending and the corresponding numerical models were established to conduct parametric studies. The effects of some key parameters such as the non-dimensional member slenderness and the height-to-width ratio, were investigated based on the verified numerical models. Also, the results obtained from the parametric studies were compared with the predictions calculated by different design codes including the Chinese design code (GB50017-2003, 2003), the new draft version of Chinese design code (GB50017-201X, 2012), Eurocode 3 (EC3, 2005) and the North America design code (ANSI/AISC360-10, 2010). These comparisons indicated that the sectional height-to-width ratio does not play an important role to influence the overall stability load-carrying capacity of Q460GJ structural steel beams with welded I-shaped cross-sections. It was also found that the design methods in GB50017-2003 and ANSI/AISC360-10 overestimate the overall stability and load-carrying capacity of Q460GJ welded I-shaped cross-section beams.
1567
66348
Experimental Investigation on Residual Stresses in Welded Medium-Walled I-Shaped Sections Fabricated from Q460GJ Structural Steel Plates
Abstract:
GJ steel is a new type of high-performance structural steel has been increasingly adopted in practical engineering. Q460GJ structural steel has a nominal yield strength of 460 MPa, which does not decrease significantly with the increase of steel plate thickness like normal structural steel. Thus, Q460GJ structural steel is normally used in medium-walled welded sections. However, research works on the residual stress in GJ steel members are few though it is one of the vital factors that can affect the member and structural behavior. This article aims to investigate the residual stresses in welded I-shaped sections fabricated from Q460GJ structural steel plates by experimental tests. A total of 4 full scale welded medium-walled I-shaped sections, were tested by sectioning method. Both circular curve correction method and straightening measurement method were adopted in this study to obtain the final magnitude and distribution of the longitudinal residual stresses. In addition, this paper also explores the interaction between flanges and webs. And based on the statistical evaluation of the experimental data, a multilayer residual stress model is proposed.
1566
66252
A Quick Method for Seismic Vulnerability Evaluation of Offshore Structures by Static and Dynamic Nonlinear Analyses
Abstract:
To evaluate the seismic vulnerability of vital offshore structures with the highest possible precision, Nonlinear Time History Analyses (NLTHA), is the most reliable method. However, since it is very time-consuming, a quick procedure is greatly desired. This paper presents a quick method by combining the Push Over Analysis (POA) and the NLTHA. The POA is preformed first to recognize the more critical members, and then the NLTHA is performed to evaluate more precisely the critical members’ vulnerability. The proposed method has been applied to jacket type structure. Results show that combining POA and NLTHA is a reliable seismic evaluation method, and also that none of the earthquake characteristics alone, can be a dominant factor in vulnerability evaluation.
1565
66231
Collapse Analysis of Planar Composite Frame under Impact Loads
Abstract:
Concrete filled steel tubular (CFST) structure has been widely used in construction practices due to its superior performances under various loading conditions. However, limited studies are available when this type of structure is subjected to impact or explosive loads. Current methods in relevant design codes are not specific for preventing progressive collapse of CFST structures. Therefore, it is necessary to carry out numerical simulations on CFST structure under impact loads. In this study, finite element analyses are conducted on the mechanical behaviour of composite frames which composed of CFST columns and steel beams subject to impact loading. In the model, CFST columns are simulated using finite element software ABAQUS. The model is verified by test results of solid and hollow CFST columns under lateral impacts, and reasonably good agreement is obtained through comparisons. Thereafter, a multi-scale finite element modelling technique is developed to evaluate the behaviour of a five-storey three-span planar composite frame. Alternate path method and direct simulation method are adopted to perform the dynamic response of the frame when a supporting column is removed suddenly. In the former method, the reason for column removal is not considered and only the remaining frame is simulated, whereas in the latter, a specific impact load is applied to the frame to take account of the column failure induced by vehicle impact. Comparisons are made between these two methods in terms of displacement history and internal force redistribution, and design recommendations are provided for the design of CFST structures under impact loads.
1564
66198
Compressive Strength and Water Sorptivity of Lightweight Aggregate Concrete
Authors:
Abstract:
In this paper, the effect of steam curing on the compressive strength development and water sorptivity of concretes that composes of different volumes of lightweight fly ash aggregate (LWA) were studied. A constant amount of lightweight coarse (LWCA) aggregate and different percentage of lightweight fine aggregate (LWFA) were utilized to produce the concrete. Various amount of LWFA was attained by volumetric substitution of fine aggregate, six various replacement levels as, 0%, 25%, 50%, 75%, and 100% were used. Hence, six different concrete mixtures were produced for this experimental study. Steam curing method was applied to the concrete production. At first concrete productions were subjected to steam curing (SC), and then were moved to water until testing date. Development of compressive strength test was applied over 56 days. And the water sorptivity test was held at 28 and 56 days.
1563
66194
Punching Shear Strengthening of Reinforced Concrete Flat Slabs Using Internal Square Patches of Carbon Fiber Reinforced Polymer
Authors:
Abstract:
This research presents a strengthening technique for enhancing the punching shear resistance of concrete flat slabs. Internal square patches of CFRP were centrally installed inside 450*450mm concrete panels during casting at a chosen distance from the tension face to produce six simply supported samples. The dimensions of those patches ranged from 50*50mm to 360*360mm. All the examined slabs contained the same amount of tensile reinforcement, had identical dimensions, were designed according to the American Concrete Institute code (ACI) and tested to failure. Compared to the control unstrengthened spacemen, all the strengthened slabs have shown an enhancement in punching capacity and stiffness. This enhancement has been found to be proportional to the area of the installed CFRP patches. In addition to the reasonably enhanced stiffness and punching shear, this strengthening technique can change the slab failure mode from shear to flexural.
1562
65989
Comparative Studies of Streamflow Models Upstream of Large Weir Systems in Thailand
Abstract:
This research was conducted in the upstream of the Mae Yom Irrigation Project whereas located in the Upper Yom River Basin in Phrae province, Thailand. The Yom River, particularly in the upstream area, comprises of many tributary streams and produces inflow to this irrigation project and downstream of the Yom Basin. The Mae Yom irrigation project was constructed by the Royal Irrigation Department (RID) since 1947 and defined as a large irrigation scheme by the large weir in Thailand with the commanded area of 35840 ha. The main structures were a control ogee-weir type with the height 7.5 m and width of 350.0 m and comprised of 2-main irrigation canals lined with concrete in a right main canal, and another left is earth channel with a total length of 130 km. The most common troublesome in this area floods during heavy rainfall because none of any dam in the upstream watershed yet which can be considered as flood prediction in the ungauged basin (PUB). The authors applied the Hydrologic Modeling System (HMS) as a rainfall-runoff model and the Soil and Water Assessment Tool (SWAT) as comparative studies for synthesizing the streamflow during the largest flood period in 2011. The results from both models with daily and monthly streamflow simulations fitted to the observed data at upstream gauging station recorded by the RID. The capabilities of both models were tested by using the Nash and Sutcliffe Efficiency (NSE), correlation coefficient (R2), and the Root Mean Square Error (RMSE). The results showed that monthly simulation of both models is better fitted the observed values than daily simulation. Therefore, both models can be predicted monthly streamflow to the Mae Yom River as for efficiently flood management in the irrigation project in light of climate change impacts.
1561
65941
Development and Characterization of Sustainable One-Part Geopolymer Cement
Abstract:
The work on indigenous binders in this paper focused on the following indigenous raw materials: red clay, red lava, and pumice (as primary aluminosilicate precursors), wood ash and gypsum (as supplementary minerals), and sodium sulfate and lime (as alkali activators). The experimental methods used for evaluation of these indigenous raw materials included laser granulometry, x-ray fluorescence (XRF) spectroscopy, and chemical reactivity. Formulations were devised for transforming these raw materials into alkali aluminosilicate-based hydraulic cement. These formulations were processed into hydraulic cement via simple heating and milling actions to render thermal activation, mechanochemical and size reduction effects. The resulting hydraulic cements were subjected to laser granulometry, the heat of hydration and reactivity tests. These cements were also used to prepare mortar mixtures, which were evaluated via performance of compressive strength tests. The measured values of strength were correlated with the reactivity, size distribution and microstructural features of raw materials. Some of the indigenous hydraulic cements produced in this reporting period yielded viable levels of compressive strength. The correlation trends established in this work are being evaluated for development of simple and thorough methods of qualifying indigenous raw materials for use in the production of indigenous hydraulic cements.
1560
65894
Tall Building Transit-Oriented Development (TB-TOD) and Energy Efficiency in Suburbia: Case Studies, Sydney, Toronto, and Washington D.C.
Abstract:
As the world continues to urbanize and suburbanize, where suburbanization associated with mass sprawl has been the dominant form of this expansion, sustainable development challenges will be more concerned. Sprawling, characterized by low density and automobile dependency, presents significant environmental issues regarding energy consumption and Co2 emissions. This paper examines the vertical expansion of suburbs integrated into mass transit nodes as a planning strategy for boosting density, intensification of land use, conversion of single family homes to multifamily dwellings or mixed use buildings and development of viable alternative transportation choices. It analyzes the spatial patterns of tall building transit-oriented development (TB-TOD) of suburban regions in Sydney (Australia), Toronto (Canada), and Washington D.C. (United States). The main objectives of this research seek to understand the effect of the new morphology of suburban tall, the physical dimensions of individual buildings and their arrangement at a larger scale with energy efficiency. This study aims to answer these questions: 1) why and how can the potential phenomenon of vertical expansion or high-rise development be integrated into suburb settings? 2) How can this phenomenon contribute to an overall denser development of suburbs? 3) Which spatial pattern or typologies/ sub-typologies of the TB-TOD model do have the greatest energy efficiency? It addresses these questions by focusing on 1) energy, heat energy demand (excluding cooling and lighting) related to design issues at two levels: macro, urban scale and micro, individual buildings—physical dimension, height, morphology, spatial pattern of tall buildings and their relationship with each other and transport infrastructure; 2) Examining TB-TOD to provide more evidence of how the model works regarding ridership. The findings of the research show that the TB-TOD model can be identified as the most appropriate spatial patterns of tall buildings in suburban settings. And among the TB-TOD typologies/ sub-typologies, compact tall building blocks can be the most energy efficient one. This model is associated with much lower energy demands in buildings at the neighborhood level as well as lower transport needs in an urban scale while detached suburban high rise or low rise suburban housing will have the lowest energy efficiency. The research methodology is based on quantitative study through applying the available literature and static data as well as mapping and visual documentations of urban regions such as Google Earth, Microsoft Bing Bird View and Streetview. It will examine each suburb within each city through the satellite imagery and explore the typologies/ sub-typologies which are morphologically distinct. The study quantifies heat energy efficiency of different spatial patterns through simulation via GIS software.
1559
65883
Analysis of the Premature In-Service Failure of Engine Mounting Towers of an Industrial Generator
Abstract:
This paper presents an investigation of the premature in-service failure of the engine mounting towers that form part of the bedframe commonly used for industrial power generation applications. The client during a routine in-service assessment of the generator set observed that the engine mounting towers had cracked. Thus, this study has investigated in detail the origin of the crack and proffered solutions to prevent a re-occurrence. Seven step problem solving methodology was followed during this paper. The study used both experimental and numerical approaches to understand, monitor and evaluate the cause and evolution of the premature failure. Findings from this study indicated that the failure resulted from a combination of varied processes from procurement of material parts, material selection, welding processes and inaptly designed load-bearing mechanics of the generating set and its mounting arrangement. These in-field observations and experimental simulations provided insights to design and validate a numerical finite element sub-model of the cracked bedframe considering thermal cycling: designed as part of these investigations. Resulting findings led to a recommendation of several procedural changes that should be adopted by the manufacturer, in order to prevent the re-occurrence of such pre-mature failure in future industrial applications.
1558
65814
Alternative Housing Solutions in Southern California
Abstract:
The perpetually growing population and economy within the United States necessitates building construction of all types. Increased building generates environmental concerns, and rightfully so. This industry accounts for approximately 4% of the total GDP in the United States while creating around two-thirds of the material waste annually. The green building movement is certainly gaining popularity in both application and recognition through entities such as the United States Green Building Council (USGBC) and their LEED program; however, builders are also producing their ideas. Alternative housing solutions that include pre-fabricated building components and shipping container homes are making great strides in the residential construction industry, and will certainly play an important role in the future. This paper will compare the cost and schedule of modular, panelized and shipping container homes to traditional stick frame home construction in the Greater Los Angeles Metropolitan Area and recommend the best application for each option.
1557
65803
Identification of Hedgerows in the Agricultural Landscapes of Mugada within Bartın Province, Turkey
Abstract:
Biotopes such as forest areas rich in biodiversity, wetlands, hedgerows and woodlands play important ecological roles in agricultural landscapes. Of these semi-natural areas and features, hedgerows are the most common landscape elements. Their most significant features are that they serve as a barrier between the agricultural lands, serve as shelter, add aesthetical value to the landscape and contribute significantly to the wildlife and biodiversity. Hedgerows surrounding agricultural landscapes also provide an important habitat for pollinators which are important for agricultural production. This study looks into the identification of hedgerows in agricultural lands in the Mugada rural area within Bartın province, Turkey. From field data and-and satellite images, it is clear that in this area, especially around rural settlements, large forest areas have been cleared for settlement and agriculture. A network of hedgerows is also apparent, which might potentially play an important role in the otherwise open agricultural landscape. We found that these hedgerows serve as an ecological and biological corridor, linking forest ecosystems. Forest patches of different sizes and creating a habitat network across the landscape. Some examples of this will be presented. The overall conclusion from the study is that ecologically, biologically and aesthetically important hedge biotopes should be maintained in the long term in agricultural landscapes such as this. Some suggestions are given for how they could be managed sustainably into the future.
1556
65671
Barrier Analysis of Sustainable Development of Small Towns: A Perspective of Southwest China
Abstract:
The past urbanization process in China has brought out series of problems, the Chinese government has then positioned small towns in essential roles for implementing the strategy 'The National New-type Urbanization Plan (2014-2020)'. As the connector and transfer station of cities and countryside, small towns are important force to narrow the gap between urban and rural area, and to achieve the mission of new-type urbanization in China. The sustainable development of small towns plays crucial role because cities are not capable enough to absorb the surplus rural population. Nevertheless, there are various types of barriers hindering the sustainable development of small towns, which led to the limited development of small towns and has presented a bottleneck in Chinese urbanization process. Therefore, this paper makes deep understanding of these barriers, thus effective actions can be taken to address them. And this paper chooses the perspective of Southwest China (refers to Sichuan province, Yunnan province, Guizhou province, Chongqing Municipality City and Tibet Autonomous Region), cause the urbanization rate in Southwest China is far behind the average urbanization level of the nation and the number of small towns accounts for a great proportion in mainland China, also the characteristics of small towns in Southwest China are distinct. This paper investigates the barriers of sustainable development of small towns which located in Southwest China by using the content analysis method, combing with the field work and interviews in sample small towns, then identified and concludes 18 barriers into four dimensions, namely, institutional barriers, economic barriers, social barriers and ecological barriers. Based on the research above, questionnaire survey and data analysis are implemented, thus the key barriers hinder the sustainable development of small towns in Southwest China are identified by using fuzzy set theory, those barriers are, lack of independent financial power, lack of construction land index, financial channels limitation, single industrial structure, topography variety and complexity, which mainly belongs to institutional barriers and economic barriers. In conclusion part, policy suggestions are come up with to improve the politic and institutional environment of small town development, also the market mechanism are supposed to be introduced to the development process of small towns, which can effectively overcome the economic barriers, promote the sustainable development of small towns, accelerate the in-situ urbanization by absorbing peasants in nearby villages, and achieve the mission of new-type urbanization in China from the perspective of people-oriented.
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65658
Analysing the Permanent Deformation of Cohesive Subsoil Subject to Long Term Cyclic Train Loading
Abstract:
Subgrade soils of railway infrastructure are subjected to a significant number of load applications over their design life. The use of slab track on existing and future proposed rail links requires a reduced maintenance and repair regime for the embankment subgrade, due to restricted access to the subgrade soils for remediation caused by cyclic deformation. It is, therefore, important to study the deformation behaviour of soft cohesive subsoils induced as a result of long term cyclic loading. In this study, a series of oedometer tests and cyclic triaxial tests (10,000 cycles) have been undertaken to investigate the undrained deformation behaviour of soft kaolin. X-ray Computer Tomography (CT) scanning of the samples has been performed to determine the change in porosity and soil structure density from the sample microstructure as a result of the laboratory testing regime undertaken. Combined with the examination of excess pore pressures and strains obtained from the cyclic triaxial tests, the results are compared with an existing analytical solution for long term settlement considering repeated low amplitude loading. Modifications to the analytical solution are presented based on the laboratory analysis that shows good agreement with further test data.
1554
65559
Research on Aerodynamic Brake Device for High-Speed Train
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Abstract:
This study is about an aerodynamic brake device for a high-speed train. In order to apply an aerodynamic brake device, an influence of the aerodynamic brake device on a high-speed train was studied aerodynamically, acoustically and dynamically. Wind tunnel test was conducted to predict an effect of braking distance reduction with a scale model of 1/30. Aerodynamic drag increases by 244% with a brake panel of a 90 degree angle. Braking distance for an emergency state was predicted to decrease by 13%.
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65523
Selection of Intensity Measure in Probabilistic Seismic Risk Assessment of Turkish Railway Bridge
Abstract:
Fragility curve is an effective common used tool to determine earthquake performance of the structural and nonstructural component. Also, it is used to determine the nonlinear behavior of bridges. There are many historical bridges in Turkish railway system. Earthquake performances of these bridges are needed to be investigated. To derive fragility curve intensity measure (IMs) and engineering demand parameters (EDP) are needed to be determined. And the relation between IMs and EDP are needed to be derived. In this study, a typical simply supported steel girder riveted railway bridge is studied. Fragility curves of this bridge are derived for two longitudinal and one horizontal direction by two parameters lognormal distribution. Time history analyses are done for 60 different real earthquake data to determine the relation IMs and EDP. Moreover, efficiency, practicality, and sufficiency of two different intensity measures are discussed. PGA, Sa(0.2s) and Sa(1s) are most common used IMs parameter for fragility curve in the literature, and are taken into consideration in terms of efficiency, practicality, and sufficiency.