International Science Index

International Journal of Civil and Environmental Engineering

Indian Railway Suspension and Braking Run-Time System Modification by System Calls Modeling through Extract, Transform and Load Process Software Engineering with Aurelia, Chef, CloudI, Erlang, FLOWer and Mercury Modules
Indian Railways is under continuous scrutiny after evolution from 1600 – 1800 British Queen Elizabeth – Queen Victoria Railway Models in India [Bharat or Hindustan]. Our Railway Theory was a Rapunzel - Disney – Bombay Movie Industry Fairy Tale which evolved from Manual to Automated [Driverless – New Technology] Systems. Here we consider the Mechanical and Electrical Transformation Condition for Suspension and Braking Systems as: Indian Railway Suspension and Braking Run-Time System Modification by System Calls Modeling through ETL Software Engineering with Aurelia, Chef, Cloudera, CloudI, Ansible Tower, Crystal, eggPlant, Erlang, FLOWer, Lava, Lift, Mars, Mercury, RabbitMQ, Ruby on Rails and Umbrella Programming with Matlab, LabView, AnyRail, SCARM and Universal Mechanism Programming and Testing Modules. In this system, we generate System Calls to the Target Database and a Fairy Tale Transformation from Housemaid Cinderella to Queen Cinderella occurs in all Mechanical Parameters to do All Test Pass [ATP] condition for New Railway Mechanical Systems just like ATPL License for an Indian DGCA approved Pilot. The system analysis is based on Module Analysis on our IIT – Space Station [DTN] Systems with Universal Mechanism communicating with Matlab and LabView in testing and programming codes with Aurelia, Chef, Cloudera, CloudI, Crystal, eggPlant, Erlang, FLOWer, Lava, Lift, Mars, Ansible Tower, Mercury, RabbitMQ, AnyRail, SCARM, Ruby on Rails and Umbrella in a non-abusive data handling scenarios for Data Centers like Infosys, Wipro, Airtel, Cognizant, TCS, Accenture, IBM, CSC, etc by giving good work environments.
Improving Swelling Performance Using Industrial Waste Products
Expansive soils regarded as one of the most problematic unsaturated formations in the Egyptian arid zones and present a great challenge in civil engineering, in general, and geotechnical engineering, in particular. Severe geotechnical complications and consequent structural damages have been arising due to an excessive and differential volumetric change upon wetting and change in water content. Different studies have been carried out concerning the swelling performance of the expansive soils using different additives including phospho-gypsum as an industrial waste product. However, this paper describes the results of a comprehensive testing programme that was carried out to investigate the effect of phospho-gypsum (PG) and sodium chloride (NaCl), as an additive mixture, on the swelling performance of constituent samples of swelling soils. The constituent samples comprise commercial bentonite collected from a natural site, mixed with different percentages of PG-NaCl mixture. The testing programme had been scoped to cover the physical and chemical properties of the constituent samples. In addition, a mineralogical study using x-ray diffraction (XRD) was performed on the collected bentonite and the mixed bentonite with PG-NaCl mixture samples. The obtained results of this study showed significant improvement in the swelling performance of the tested samples with the increase of the proposed PG-NaCl mixture content
Best Combination of Design Parameters for Buildings with Buckling-Restrained Braces
Buildings vulnerability due to seismic activity has been highly studied since the middle of last century. As a solution to the structural and non-structural damage caused by intense ground motions, several seismic energy dissipating devices, such as buckling-restrained braces (BRB), have been proposed. BRB have shown to be effective in concentrating a large portion of the energy transmitted to the structure by the seismic ground motion. A modern design approach for buildings with BRB elements, which is based on a seismic Displacement-Based formulation, has recently been proposed. It is a practical and easy design method which simplifies the work of structural engineers. That method is used here for the design of the structure-BRB damper system. The objective of the present study is to develop a methodology to find the best combination of design parameters on structural frame – BRB systems, taking into account simultaneously: 1) initial costs of a multiple-degree-of-freedom (MDOF) structural system, and 2) an adequate engineering demand parameter. The design parameters considered here are: the stiffness ratio (α = Kframe/Ktotal), and the strength ratio (γ = Vdamper/Vtotal); where K represents structural stiffness and V structural strength; and the subscripts "frame", "damper" and "total" represent: the structure without dampers, the BRB dampers, and the total frame-damper system, respectively. The selection of the best combination of design parameters α and γ is based on an initial costs analysis and on the structural dynamic response of the structural frame-damper system. The methodology is applied to an 8-story 3-bay steel building with BRB, which is located on soft soil of Mexico City. Several ground motions recorded in the soft soil of Mexico City, caused by subduction events, are used for the analysis. It is found the best combination of design parameters for the building with BRB under study.
Influence of Local Soil Conditions on Optimal Load Factors for Seismic Design of Buildings
Optimal load factors (dead, live and seismic) used for the design of buildings may be different, depending on the seismic ground motion characteristics to which they are subjected, which are closely related to the type of soil conditions where the structures are located. Using a criterion of optimization, the influence of the type of soil on those load factors is analyzed in the present study. A methodology that is useful for establishing optimal load factors that minimize the cost over the life cycle of the structure is employed; and as a restriction, it is established that the probability of structural failure must be less than or equal to a prescribed value. The life-cycle cost model used here includes different types of costs. The optimization methodology is applied to two groups of reinforced concrete buildings. One set (consisting on 4- and 7-story buildings) is located on the firm ground (with a dominant period Ts ≈ 0.5s) and the other (consisting on 7- and 11-story buildings) on soft soil (Ts ≈1.5s) of Mexico City. Each group of buildings is designed using different combinations of load factors. Through incremental dynamic analyses, the statistics of the maximums inter-story drifts (associated with the structural capacity) are found. The buildings located on the firm zone are analyzed under the action of 10 strong seismic records, and those on soft zone, under 12 strong ground motions. All the motions correspond to seismic subduction events with magnitudes M ≥ 6.9. Then, the structural damage and the total costs expected, corresponding to each group of buildings, are estimated. It is concluded that the optimal load factors combination is different for the design of buildings located on firm ground than that for buildings located on soft soil.
Prediction of Service Life of Tunnel Structures Subjected to Water Seepage
Water seepage is one of the most common causes of damage in tunnel structures, which can cause direct and indirect e.g. reinforcement corrosion and calcium leaching damages. Estimation of water seepage or inflow is one of the main challenges in probabilistic assessment of tunnels. The methodology proposed in this study is an attempt for mathematically modeling the water seepage in tunnel structures and further predicting its service life. Using the time-dependent reliability, water seepage is formulated as a failure mode, which can be used for prediction of service life. Application of the formulated seepage failure mode to a case study tunnel is presented.
Optimum Maintenance Management Approach for Water Pipe Networks Using Reliability Based Technique
With a large percentage of the countries’ total infrastructure expenditure attributed to water network maintenance, it is essential to optimise maintenance strategies to rehabilitate or replace underground pipes before failure occurs. The aim of this paper is to provide water utility managers with a maintenance management approach for underground water pipes, subject to external loading and material corrosion, to give the lowest life cycle cost over a predetermined time period. This reliability based maintenance management methodology details the optimal years for intervention, the ideal number of maintenance activities to perform before replacement and specifies feasible renewal options and intervention prioritisation to minimise the life cycle cost. The study was then extended to include feasible renewal methods by determining the structural condition index and potential for soil loss, then obtaining the failure impact rating to assist in prioritising pipe replacement. A case study on optimisation of maintenance plans for the Melbourne water pipe network is considered in this paper to evaluate the practicality of the proposed methodology. The results confirm that the suggested methodology can provide water utility managers with a reliable systematic approach to determining optimum maintenance plans for pipe networks.
Lifespan Assessment of the Fish Crossing System of Itaipu Power Plant (Brazil/Paraguay) Based on the Reaching of Its Sedimentological Equilibrium Computed by 3D Modeling and Churchill Trapping Efficiency
This study aimed to assess the lifespan of the fish transposition system of the Itaipu Power Plant (Brazil/Paraguay) by using 3D hydrodynamic modeling and Churchill trapping effiency in order to identify the sedimentological equilibrium configuration in the main pond of the Piracema Channel, which is part of a 10 km hydraulic circuit that enables fish migration from downstream to upstream (and vice-versa) the Itaipu Dam, overcoming a 120 m water drop. For that, bottom data from 2002 (its opening year) and 2015 were collected and analyzed, besides bed material at 12 stations to the purpose of identifying their granulometric profiles. The Shields and Yalin and Karahan diagrams for initiation of motion of bed material were used to determine the critical bed shear stress for the sedimentological equilibrium state based on the sort of sediment (grain size) to be found at the bottom once the balance is reached. Such granulometry was inferred by analyzing the grosser material (fine and medium sands) which inflows the pond and deposits in its backwater zone, being adopted a range of diameters within the upper and lower limits of that sand stratification. The software Delft 3D was used in an attempt to compute the bed shear stress at every station under analysis. By modifying the input bathymetry of the main pond of the Piracema Channel so as to the computed bed shear stress at each station fell within the intervals of acceptable critical stresses simultaneously, it was possible to foresee the bed configuration of the main pond when the sedimentological equilibrium is reached. Under such condition, 97% of the whole pond capacity will be silted, and a shallow water course with depths ranging from 0.2 m to 1.5 m will be formed; in 2002, depths ranged from 2 m to 10 m. Out of that water path, the new bottom will be practically flat and covered by a layer of water 0.05 m thick. Thus, in the future the main pond of the Piracema Channel will lack its purpose of providing a resting place for migrating fish species, added to the fact that it may become an insurmountable barrier for medium and large sized specimens. Everything considered, it was estimated that its lifespan, from the year of its opening to the moment of the sedimentological equilibrium configuration, will be approximately 95 years–almost half of the computed lifespan of Itaipu Power Plant itself. However, it is worth mentioning that drawbacks concerning the silting in the main pond will start being noticed much earlier than such time interval owing to the reasons previously mentioned.
Influence of the Quality of the Recycled Aggregates in Concrete Pavement.
The environmental impact has become a global concern during the last decades. Several alternatives have been proposed and studied to minimize this impact in different areas. The reuse of aggregates from old concretes to manufacture new ones not only can reduce this impact but is also a way to optimize the resource management. The effect of the origin of the reused aggregates from two different origin materials in recycled concrete pavement is studied here. Using the dosing applied by a pavement company, coarse aggregates in the 6.3-25 mm fraction are replaced by recycled aggregates with two different origins: old concrete pavements with similar origin strength to the one of the control concrete, and precast concrete pipes with smaller strengths than the one of the control concrete. The replacement percentages tested are 30%, 40% and 50% in both cases. The compressive strength tests are performed after 7, 14, 28 and 90 curing days, the flexural strength tests and the elasticity modulus tests after 28 and 90 curing days. Results show that the influence of the quality of the origin concrete in the mechanical properties of recycled concretes is not despicable. Concretes with up to a 50% of recycled aggregates from the concrete pavement have similar compressive strengths to the ones of the control concrete and slightly smaller flexural strengths that, however, in all cases exceed the minimum of 5MPa after 28 curing days stablished by the Chilean regulation for pavement concretes. On the other hand, concretes with recycled aggregates from precast concrete pipes show significantly lower compressive strengths after 28 curing days. The differences with the compressive strength of the control concrete increase with the percentage of replacement, reaching a 13% reduction when 50% of the aggregates are replaced. The flexural strength also suffers significant reductions that increase with the percentage of replacement, only obeying the Chilean regulation when 30% of the aggregates are recycled after 28 curing days. Nevertheless, after 90 curing days, all series obey the regulation requirements. Results show, not only the importance of the quality of the origin concrete, but also the significance of the curing days, that may allow the use of less quality recycled material without important strength losses.
Formulation of a Rapid Earthquake Risk Ranking Criteria for National Bridges in the National Capital Region Affected by the West Valley Fault Using GIS Data Integration
In this study, a Rapid Earthquake Risk Ranking Criteria was formulated by integrating various existing maps and databases by the Department of Public Works and Highways (DPWH) and Philippine Institute of Volcanology and Seismology (PHIVOLCS). Utilizing Geographic Information System (GIS) software, the above-mentioned maps and databases were used in extracting seismic hazard parameters and bridge vulnerability characteristics in order to rank the seismic damage risk rating of bridges in the National Capital Region.
The Influence of Infiltration and Exfiltration Processes on Maximum Wave Run-Up: A Field Study on Trinidad Beaches
Wave run-up may be defined as the time-varying position of the landward extent of the water’s edge, measured vertically from the mean water level position. The hydrodynamics of the swash zone and the accurate prediction of maximum wave run-up, play a critical role in the study of coastal engineering. The understanding of these processes is necessary for the modeling of sediment transport, beach recovery and the design and maintenance of coastal engineering structures. However, due to the complex nature of the swash zone, there remains a lack of detailed knowledge in this area. Particularly, there has been found to be insufficient consideration of bed porosity and ultimately infiltration/exfiltration processes, in the development of wave run-up models. Theoretically, there should be an inverse relationship between maximum wave run-up and beach porosity. The greater the rate of infiltration during an event, associated with a larger bed porosity, the lower the magnitude of the maximum wave run-up. Additionally, most models have been developed using data collected on North American or Australian beaches and may have limitations when used for operational forecasting in Trinidad. This paper aims to assess the influence and significance of infiltration and exfiltration processes on wave run-up magnitudes within the swash zone. It also seeks to pay particular attention to how well various empirical formulae can predict maximum run-up on contrasting beaches in Trinidad. Traditional surveying techniques will be used to collect wave run-up and cross-sectional data on various beaches. Wave data from wave gauges and wave models will be used as well as porosity measurements collected using a double ring infiltrometer. The relationship between maximum wave run-up and differing physical parameters will be investigated using correlation analyses. These physical parameters comprise wave and beach characteristics such as wave height, wave direction, period, beach slope, the magnitude of wave setup, and beach porosity. Most parameterizations to determine the maximum wave run-up are described using differing parameters and do not always have a good predictive capability. This study seeks to improve the formulation of wave run-up by using the aforementioned parameters to generate a formulation with a special focus on the influence of infiltration/exfiltration processes. This will further contribute to the improvement of the prediction of sediment transport, beach recovery and design of coastal engineering structures in Trinidad.
Thermal Performance of Common Building Insulation Materials: Operating Temperature and Moisture Effect
An accurate prediction of the heat transfer through the envelope components of building is required to achieve an accurate cooling/heating load calculation which leads to precise sizing of the hvac equipment. This also depends on the accuracy of the thermal conductivity of the building insulation material. The proper use of thermal insulation in buildings (k-value) contribute significantly to reducing the HVAC size and consequently the annual energy cost. The first part of this paper presents an overview of building thermal insulation and their applications. The second part presents some results related to the change of the polystyrene insulation thermal conductivity with the change of the operating temperature and the moisture. Best-fit linear relationship of the k-value in term of the operating temperatures and different percentage of moisture content by weight has been established. The thermal conductivity of the polystyrene insulation material increases with the increase of both operating temperature and humidity content.
Long-Term Field Performance of Paving Fabric Interlayer Systems to Reduce Reflective Cracking
The formation of reflective cracking of pavement overlays has confronted highway engineers for many years. Stress-relieving interlayers, such as paving fabrics, have been used in an attempt to reduce or delay reflective cracking. The effectiveness of paving fabrics in reducing reflection cracking is related to joint or crack movement in the underlying pavement, crack width, overlay thickness, subgrade conditions, climate, and traffic volume. The nonwoven geotextiles are installed between the old and new asphalt layers. Paving fabrics enhance performance through two mechanisms: stress relief and waterproofing. Several factors including proper installation, remedial work performed before overlay, overlay thickness, variability of pavement strength, existing pavement condition, base/subgrade support condition, and traffic volume affect the performance. The primary objective of this study was to conduct a long-term monitoring of the paving fabric interlayer systems to evaluate its effectiveness and performance. A comprehensive testing, monitoring, and analysis program were undertaken, where twelve 500-ft pavement sections of a four-lane highway were rehabilitated, and then monitored for seven years. A comparison between the performance of paving fabric treatment systems and control sections is reported. Lessons learned, and the various factors are discussed.
The Impact of Roof Thermal Performance on the Indoor Thermal Comfort in a Natural Ventilated Building Envelope in Hot Climatic Climates
Global warming has become a threat of our time. It poses challenges to the existence of beings on earth, the built environment, natural environment and has made a clear impact on the level of energy and water consumption. As such, increase in the ambient temperature increases indoor and outdoor temperature level of the buildings which brings about the use of more energy and mechanical air conditioning systems. In addition, in view of the increased modernization and economic growth in the developing countries, a significant amount of energy is being used, especially those with hot climatic conditions. Since modernization in developing countries is rising rapidly, more pressure is being placed on the buildings and energy resources to satisfy the indoor comfort requirements. This paper presents a sustainable passive roof solution as a means of reducing energy cooling loads for satisfying human comfort requirements in a hot climate. As such, the study based on the field study data discusses indoor thermal roof design strategies for a hot climate by investigating the impacts of roof thermal performance on indoor thermal comfort in naturally ventilated building envelope small scaled structures. In this respect, the traditional concrete flat roof, corrugated galvanised iron roof and pre-painted standing seam roof were used. The experiment made used of three identical small scale physical models constructed and sited on the roof of a building at the University of the West Indies. The results show that the utilization of insulation in traditional roofing systems will significantly reduce heat transfer between the internal and ambient environment, thus reducing the energy demand of the structure and the relative carbon footprint of a structure per unit area over its lifetime. Also, the application of flat slab concrete roofing system showed the best performance as opposed to the metal roof sheeting alternative systems. In addition, it has been shown experimentally through this study that a sustainable passive roof solution such as insulated flat concrete roof in hot dry climate has a better cooling strength that can provide building occupant with a better thermal comfort, conducive indoor conditions and energy efficiency.
Effect of Different Plan Shapes on the Load Carrying Capacity of a Steel Frame under Extreme Loading
An increase in accidental explosions in recent years has increased the interest on investigating the response and behavior of structures in more details. The present work focused on finite element analysis of multistory steel frame structures with different plan shapes subjected to blast loadings. In order to study the effect of the geometry of the building, three different shapes for the plan of the building were modeled and studied; Rectangular, Square and L shape plans. The nonlinear dynamic analysis was considered in this study. The relocation technique was also used to improve the behavior of structure. The accuracy of the multistory frame model was confirmed with those of the existing study in the literature and they were in good agreement. The effect of span length of the buildings was also considered. Finite element analysis of various scenarios for relocating the plastic hinges and improving the response of the structure was performed. The base shear versus displacement curves were compared to reveal the best possible scenarios to provide recommendations to designers and practitioners.
Effect of Local Factors on Concentrations and Flora of Viable Fungi in School Buildings
Although not enough dose-response data are available for the setting of any health-based criteria on bioaerosol levels, indoor microbial exposure has been related to a range of adverse health effects such as respiratory illnesses and allergies among human beings. Thus it is important to know all contributing factors of composition and concentration of indoor bioaerosols including fungal levels in indoor air. The aim of this study was to review and summarize the local factors affecting concentrations of viable fungi in school environments. The material in this literature review consists of peer-reviewed journal articles searched by using PubMed and Google Scholar and by searching the lists of references of relevant articles (based on their title and abstract). An analysis of the resulting data confirmed that there is strong scientific evidence that the mold/moisture damage and the type of ventilation affect the concentration of viable fungi in the school buildings. In addition, there is scientific evidence that the age of the building, the building frame material, existence of carpet, moisture-damage repairs, outdoor fungal concentration, sampling at the different time of the day, the temperature/relative humidity/season and the ventilation rate influence measured viable fungi concentrations in the school buildings. This study offer valuable information, which can be used in the interpretation of the fungal analysis and to decrease microbial exposure by reducing to known sources and/or contributing factors. However, more studies of different local factors contributing the human microbial exposure in school buildings ̶ as well as other type of buildings and different indoor environments are needed.
A Hybrid Stainless Steel Girder for Bridge Construction
The main object of this paper is to present the research results of the development of a hybrid stainless steel bridge construction undertaken at the University of Ryukyu. When compared to conventional steels, stainless steel has much higher corrosion resistance, lower maintenance costs, greater durability, and is more aesthetical appealing. However historically, stainless steels have rarely been used in bridge construction due to their initial cost. Hence, in order to reduce the initial cost, we developed a smart bridge structural system, a hybrid stainless steel bridge. The outside of the hybrid bridge construction exposed to the open air is composed by stainless steel plates, and the inside is constituted by conventional structural steel elements, such as cross beams, stiffeners, ribs, bracings, gusset plates, etc. The cost reduction is brought by this hybrid treatment. It is verified analytically and experimentally that a conventional design method to evaluate the strength of steel members is available for the hybrid members. The benefit of the whole life cost of the hybrid stainless steel bridge is shown by comparing with the life cycle cost of the hybrid bridge with that of a conventional steel bridge.
Structural Engineering Forensic Evaluation of Misdiagnosed Concrete Block Wall Cracking
Given that concrete block walls are expected to experience shrinkage throughout their service life, cracking is to be expected. However, after concrete block walls have been placed into service, originally anticipated cracking is often misdiagnosed as a structural defect. Such misdiagnoses often result in or are used to support litigation. This paper begins by discussing the causes and types of anticipated cracking within concrete block walls followed by a discussion on the processes that exists for properly evaluating them and their significance. From here the paper then presents a case of misdiagnoses and the flawed logic employed to support litigation.
Finite Element Modeling for Clamping Stresses Developed in Hot-Driven Steel Structural Riveted Connections
A three-dimensional finite element model is constructed to capture the stress field generated during the installation of hot-driven rivets. Clamping stress is generated when a steel rivet heated to approximately 1000°C comes in contact with the material to be fastened at ambient temperature. As the rivet cools down, thermal contraction subjects the rivet into tensile stress, while the material being fastened is subjected to compressive stress. Model characteristics and assumptions, as well as steel properties variation with respect to temperature are discussed. The thermal stresses developed around the rivet hole are assessed and reported. Results from the analysis are utilized to detect possible regions for fatigue crack propagation under cyclic loads.
Fabric-Reinforced Cementitious Matrix (FRCM)-repaired Corroded Reinforced Concrete (RC) Beams Under Monotonic and Fatigue Loads
Rehabilitating corrosion-damaged reinforced concrete (RC) structures has been accomplished using various techniques such as steel plating, external post-tensioning, and external bonding of fiber reinforced polymer (FRP) composites. This paper reports on the use of an innovative technique to strengthen corrosion-damaged RC structures using fabric-reinforced cementitious matrix (FRCM) composites. FRCM consists of dry-fiber fabric embedded in cement-based matrix. Twelve large-scale RC beams were constructed and tested in flexural monotonic and fatigue loads. Prior to testing, ten specimens were subjected to accelerated corrosion process for 140 days leading to an average mass loss in the tensile steel bars of 18.8 %. Corrosion was restricted to the main reinforcement located in the middle third of the beam span. Eight corroded specimens were repaired and strengthened while two virgin and two corroded-unrepaired/unstrengthened beams were used as benchmarks for comparison purpose. The test parameters included the FRCM materials (Carbon-FRCM, PBO-FRCM), the number of FRCM plies, the strengthening scheme, and the type of loading (monotonic and fatigue). The effects of the pervious parameters on the flexural response, the mode of failure, and the fatigue life were reported. Test results showed that corrosion reduced the yield and ultimate strength of the beams. The corroded-unrepaired specimen failed to meet the provisions of the ACI-318 code for crack width criteria. The use of FRCM significantly increased the ultimate strength of the corroded specimen by 21% and 65% more than that of the corroded-unrepaired specimen. Corrosion significantly decreased the fatigue life of the corroded-unrepaired beam by 77% of that of the virgin beam. The fatigue life of the FRCM repaired-corroded beams increased to 1.5 to 3.8 times that of the corroded-unrepaired beam but was lower than that of the virgin specimen. The specimens repaired with U-wrapped PBO-FRCM strips showed higher fatigue life than those repaired with the end-anchored bottom strips having similar number of PBO-FRCM-layers. PBO-FRCM was more effective than Carbon-FRCM in restoring the fatigue life of the corroded specimens.
Design and Analysis of Hybrid Morphing Smart Wing for Unmanned Aerial Vehicles
Unmanned aerial vehicles, of all sizes, are prime targets of the wing morphing concept as their lightweight structures demand high aerodynamic stability while traversing unsteady atmospheric conditions. In this research study, a hybrid morphing technology is developed to aid the trailing edge of the aircraft wing to alter its camber as a monolithic element rather than functioning as conventional appendages like flaps. Kinematic tailoring, actuation techniques involving shape memory alloys (SMA), piezoelectrics – individually fall short of providing a simplistic solution to the conundrum of morphing aircraft wings. On the other hand, the feature of negligible hysteresis while actuating using compliant mechanisms has shown higher levels of applicability and deliverability in morphing wings of even large aircrafts. This research paper delves into designing a wing section model with a periodic, multi-stable compliant structure requiring lower orders of topological optimization. The design is sub-divided into three smaller domains with external hyperelastic connections to achieve deflections ranging from -15° to +15° at the trailing edge of the wing. To facilitate this functioning, a hybrid actuation system by combining the larger bandwidth feature of piezoelectric macro-fibre composites and relatively higher work densities of shape memory alloy wires are used. Finite element analysis is applied to optimize piezoelectric actuation of the internal compliant structure. A coupled fluid-surface interaction analysis is conducted on the wing section during morphing to study the development of the velocity boundary layer at low Reynold’s numbers of airflow.
Investigation of the Mechanical Performance of Hot Mix Asphalt Modified with Crushed Waste Glass
The successive increase of generated waste materials like glass has led to many environmental problems. Using crushed waste glass in hot mix asphalt paving has been though as an alternative to landfill disposal and recycling. This paper discusses the possibility of utilizing crushed waste glass, as a part of fine aggregate in hot mix asphalt in Egypt. This is done through evaluation of the mechanical properties of asphalt concrete mixtures mixed with waste glass and determining the appropriate glass content that can be adapted in asphalt pavement. Four asphalt concrete mixtures with various glass contents, namely; 0%, 4%, 8% and 12% by weight of total mixture were studied. Evaluation of the mechanical properties includes performing Marshall stability, indirect tensile strength, fracture energy and unconfined compressive strength tests. Laboratory testing had revealed the enhancement in both compressive strength and Marshall stability test parameters when the crushed glass was added to asphalt concrete mixtures. This enhancement was accompanied with a very slight reduction in both indirect tensile strength and fracture energy when glass content up to 8% was used. Adding more than 8% of glass causes a sharp reduction in both indirect tensile strength and fracture energy. Testing results had also shown a reduction in the optimum asphalt content when the waste glass was used. Measurements of the heat loss rate of asphalt concrete mixtures mixed with glass revealed their ability to hold heat longer than conventional mixtures. This can have useful application in asphalt paving during cold whether or when a long period of post-mix transportation is needed.
Flood Hazards, Vulnerability Andadaptations in Upper Imo River Basin of South Eastern Nigera
Imo River Basin is located in South Eastern Nigeria comprising of 11 states of Imo, Abia, Anambra, Ebonyi, Enugu, Edo, Rivers, Cross river, AkwaIbom, Bayelsa, Delta, and Bayelsa states. The basin has a fluvial erosional system dominated by powerful rivers coming down from steep slopes in the area. This research investigated various hazards associated with flood, the vulnerable areas, elements at risk of flood and various adaptation strategies adopted by local inhabitants to cope with the hazards. The research aim is to identify, examine and assess flood hazards, vulnerability and adaptations in the Upper Imo River Basin. The study identified the role of elevation in cause of flood, elements at risk of flood as well as examine the effectiveness or otherwise of the adaptation strategies for coping with the hazards. Data for this research is grouped as primary and secondary. Their various methods of generation are field measurement, questionnaire, library websites etc. Other types of data were generated from topographical, geological, and Digital Elevation model (DEM) maps, while the hydro meteorological data was sourced from Nigeria Meteorological Agency (NIMET), Meteorological stations of Geography and Environmental Management Departments of Imo State University and Alvan Ikoku Federal College of Education. 800 copies of questionnaire were distributed using systematic sampling to 8 locations used for the pilot survey. About 96% of the questionnaire were retrieved and used for the study. 13 flood events were identified in the study area. Their causes, years and dates of events were documented in the text, and the damages they caused were evaluated. The study established that for each flood event, there is over 200mm of rain observed on the day of the flood and the day before the flood. The study also observed that the areas that situate at higher elevation (See DEM) are less prone to flood hazards while areas at low elevations are more prone to flood hazards. Elements identified to be at risk of flood are agricultural land, residential dwellings, retail trading and related services, public buildings and community services. The study thereby recommends non settlement at flood plains and flood prone areas and rearrangement of land use activities in the upper Imo River Basin among others
Cyclic Behaviour of Wide Beam-Column Joints with Shear Strength Ratios of 1.0-1.6
Beam-column connections play an important role in the reinforced concrete moment resisting frame (RCMRF), which is one of the most commonly used structural systems around the world. The premature failure of such connections would severely limit the seismic performance and increase the vulnerability of RCMRF. In the past decades, researchers primarily focused on investigating the structural behaviour and failure mechanisms of conventional beam-column joints, the beam width of which is either smaller than or equal to the column width, while studies in wide beam-column joints were scarce. This paper presents the primary experimental results of three full-scale wide beam-column connections, which are mainly designed and detailed according to ACI 318-14 and ACI 352R-02, under reversed cyclic loading. Ratios of the nominal shear strength to the design shear strength of these specimens are 1.0, 1.3 and 1.6 respectively so as to probe into differences of the joint shear strength between experimental results and predictions by design codes of practice. Flexural failure dominated in the first specimens in which full-width plastic hinges were formed and both beam hinges and premature joint shear failure occurred for the last two specimens. Finally, an analytical model will be provided based on the previous researchers to accurately predict the joint shear strength in wide beam joint.
Seismic Vulnerability of RC Knee Joints under Varying Opening to Closing Shear Stress Ratios
Knee joints, the beam column connections found at the roof level of a moment resisting frame buildings are inherently different from conventional interior and exterior beam column connections in the way forces from adjoining members are transferred into joint and then, resisted by the joint. A knee connection has two distinct load resisting mechanisms, each for closing and opening actions, acting simultaneously with opening shear stresses much less in magnitude as compared with closing shear stresses under reversed cyclic loading. In spite of many distinct differences in the behaviour of shear resistance in knee joints, there are no special design provisions in the major design codes available across the world due to lack of in-depth research on the knee connections. Much research work carried out on knee joints by several researchers had very low opening shear stresses: in the range of 50-70% as compared with closing shear stresses. To understand the relative importance of opening and closing actions in design, it is imperative to study knee joints under varying shear stresses especially at higher opening to closing shear stress ratios. Three knee joint specimens, under different input shear stresses, were designed as per ACI 318-14 and ACI 352R-02 to produce a varying ratio of input opening to closing shear stresses. The design was carried out in such a way that, the ratio of flexural strength of beams with consideration of axial forces in opening to closing actions are maintained at 0.5, 0.7 and 1.0, thereby resulting in the required variation of opening to closing joint shear stress ratios among the specimens. The behaviour of these specimens was then carefully studied in terms of ductility, closing and opening capacity and cracking pattern to understand the differences in joint performance, based on which, an attempt to suggest design guidelines for knee joints is made emphasizing the relative importance of opening and closing actions. Effect of anchorage of main reinforcement and joint reinforcement was also studied to improve the shear strength of knee joints.
Seismic Base Shear Force Depending on Building Fundamental Period and Site Conditions: Deterministic Formulation and Probabilistic Analysis
The aim of this paper is to investigate the effect of the building fundamental period of reinforced concrete buildings of (6, 9 and 12 storey), with different floor plans: symmetric, monosymmetric, and unsymmetric. These structures are erected at different epicentral distances. Using the Boumerdes, Algeria (2003) earthquake data, we focused primarily on the establishment of the deterministic formulation linking the base shear force to two parameters: The first one is the fundamental period, that represents the numerical fingerprint of the structure, and the second is the epicentral distance, used to represent the impact of the earthquake on this force. In a second step, with a view to highlight the effect of uncertainty on these parameters on the analyzed response, these parameters are modeled as random variables with a log-normal distribution. The variability of the coefficients of variation of the chosen uncertain parameters, on the statistics on the seismic base shear force, showed that the effect of uncertainty on fundamental period on this force statistics is low compared to the epicentral distance uncertainty influence.
Optimum Design of Reinforced Concrete Cantilever Retaining Walls Eurocode 2
This study investigates optimum design in terms of minimum cost of reinforced concrete cantilever retaining walls. For the optimisation process, the evolutionary method which is a combination of genetic algorithm and local search techniques was implemented. The evolutionary method was adopted because of its efficiency in dealing with a wide range of nonlinear engineering problems as demonstrated by several works available in the literature. Equally important, the evolutionary method is embedded within Solver add-in tool of Microsoft Excel. This implies that there is no need to pay for extra license to run any optimisation problem. The design variables of the problem are thickness of stem wall, thickness of base slab, width of the heel, width of the toe, area of steel reinforcement for the stem wall and base slab. The objective function was to minimise the total cost of the wall, which includes costs of concrete, steel, forming, and excavation. The constrained functions were set to satisfy provisions and requirements of Eurocode 2 (EC2). Material strength and soil characteristics are treated as design parameters where they are kept constants during the solution of the problem. Various material cost ratios were considered. Consequently, optimum design charts were developed for a wide range of wall height, coefficient of friction and surcharge load. Following a comprehensive investigation of the minimum cost problems carried out for different cases, one can conclude that the total cost of the retaining wall is directly proportional to the wall height and surcharge load values. Whereas, the cost is almost independent of the coefficient of friction.
Study of Landslide Behavior with Topographic Monitoring and Numerical Modeling
Landslide of Ain El Hammam (AEH) has been an old slip since 1969; it was reactivated after an intense rainfall period in 2008.which it presents a complex shape and affects broad areas. The up courses consist of satin gray schist usually out grow a thick clayey silt cover. The factors following these stabilities are mostly related to the geological formation, the hydro-climatic conditions and the topography of the region. The city of AEH, located on the top of a steep slope at 50 km from the city of Tizi Ouzou (Algeria). AEH’s topographic monitoring of unstable slope allows as analyzing the structure and the different deformation mechanism and the gradual change in the geometry, the direction of change of slip, as it also allows us to delimited the area affected by the movement. It can detect early indications of rapid, catastrophic movement and provides immediate notification of landslide activity, continuous information from real-time monitoring; it also provides a better understanding of landslide behavior, enabling engineers to create more effective designs for halting landslide movement. This work aims to study the behavior of AEH landslide with topographic monitoring and to validate the results with numerical modeling of the slip site, when the hydraulic factors identified as the most important factors for the reactivation of this landslide. With the help of the numerical code Plaxis 2D and PlaxFlow the precipitations and the steady state flow are modeled. To identify the mechanism of deformation and to predict the spread of the AEH landslide numerically, we used the equivalent deviatory strain; these results were visualized by Matlab soft ware.
Plastic Behavior of Steel Frames Using Different Concentric Bracing Configurations
Among the entire natural calamities earthquake is the one which is most devastating. If the losses due to all other calamities are added still it will be very less than the losses due to earthquakes. So it means we must be ready to face such a situation, which is only possible if we make our structures earthquake resistant. A review of structural damages to the braced frame systems after several major earthquakes—including recent earthquakes—has identified some anticipated and unanticipated damage. This damage has prompted many engineers and researchers around the world to consider new approaches to improve the behavior of braced frame systems. Extensive experimental studies over the last fourty years of conventional buckling brace components and several braced frame specimens have been briefly reviewed, highlighting that the number of studies on the full-scale concentric braced frames is still limited. So for this reason the study surrounds the words plastic behavior, steel structure, brace frame system. In this study, there are two different analytical approaches which have been used to predict the behavior and strength of an un-braced frame. The first is referred as incremental elasto-plastic analysis a plastic approach. This method gives a complete load-deflection history of the structure until collapse. It is based on the plastic hinge concept for fully plastic cross sections in a structure under increasing proportional loading. In this, the incremental elasto-plastic analysis- hinge by hinge method is used in this study because of its simplicity to know the complete load- deformation history of two storey un-braced scaled model. After that the experiments were conducted on two storey scaled building model with and without bracing system to know the true or experimental load deformation curve of scaled model. Only way, is to understand and analyze these techniques and adopt these techniques in our structures. The study named as Plastic Behavior of Steel Frames using Different Concentric Bracing Configurations deals with all this. This study aimed at improving the already practiced traditional systems and to check the behavior and its usefulness with respect to X-braced system as reference model i.e. is how plastically it is different from X-braced. Laboratory tests involved determination of plastic behavior of these models (with and without brace) in terms of load-deformation curve. Thus, the aim of this study is to improve the lateral displacement resistance capacity by using new configuration of brace member in concentric manner which is different from conventional concentric brace. Once the experimental and manual results (using plastic approach) compared, simultaneously the results from both approach were also compared with nonlinear static analysis (pushover analysis) approach using ETABS i.e how both the previous results closely depicts the behavior in pushover curve and upto what limit. Tests results shows that all the three approaches behaves somewhat in similar manner upto yield point and also the applicability of elasto-plastic analysis (hinge by hinge method) to know the plastic behavior. Finally the outcome from three approaches shows that the newer one configuration which is chosen for study behaves in-between the plane frame (without brace or reference frame) and the conventional X-brace frame.
Application of Artificial Ground-Freezing to Construct a Passenger Interchange Tunnel for the Subway Line 14 in Paris, France
Artificial ground freezing (AGF) technique is a well-proven soil improvement approach used worldwide to construct shafts, tunnels and many other civil structures in difficult subsoil or ambient conditions. As part of the extension of Line 14 of the Paris subway, a passenger interchange tunnel between the new station at Porte de CI ichy and the new Tribunal the Grand Instance has been successfully constructed using this technique. The paper presents the successful application of AGF by Liquid Nitrogen and Brine implemented to provide structural stability and groundwater cut-off around the passenger interchange tunnel. The working conditions were considered to be rather challenging, due to the proximity of a hundred-year-old existing service tunnel of the Line 13, and subsoil conditions on site. Laboratory tests were carried out to determine the relevant soil parameters for hydro-thermal-mechanical aspects and to implement numerical analyses. Monitoring data were used in order to check and control the development and the efficiency of the freezing process as well as to back analyze the parameters assumed for the design, both during the freezing and thawing phases.
Comparative Study of Compressive Strength of Triangular Polyester Fiber with Fly Ash Roller Compacted Concrete Using Ultrasonic Pulse Velocity Method
This paper presents the experimental investigation results of Ultrasonic Pulse Velocity (UPV) tests conducted on roller compacted concrete pavement (RCCP) material containing Class F fly ash of as mineral admixture and triangular polyester fiber as a secondary reinforcement. The each mix design series fly ash content is varied from 0% to 45 % and triangular polyester fiber 0% to 0.75% by volume fraction. In each series and for different ages of curing (i.e. 7, 28 and 90 days) forty-eight cube specimens are cast and tested for compressive strength and UPV. The UPV of fly ash was found to be lower for all mixtures at 7 days in comparison with control mix concrete. But at 28, 56 days and 90 days the UPV were significantly improved for all the mixes. Relationships between compressive strength of RCCP and UPV and Dynamic Elastic Modulus are proposed for all series mixes.