Search results for: hydraulic concrete

Authors: Abdulrahman Abdulrahman, Abir Abdulrahman

Abstract:

The stability of slopes of earthen embankments is usually examined by Swedish slip circle method or the slices method. The factor of safety against sliding using Fellenius procedure depends upon the angle formed by the arc of sliding at the center ψ and the radius of the slip circle r. The values of both mentioned parameters ψ and r aren't precisely predicted because they are measured from the drawing. In this paper, analytical formulae were derived for finding the exact values of both ψ and r. Also this paper presents the different conditions of intersections the slip circle with the body of an earthen dam and the coordinate of intersection points. Numerical examples are chosen for demonstration the proposed solution

Keywords: earthen dams stability, , earthen embankments stability, , Fellenius method, hydraulic structures, , side slopes stability, , slices method, Swedish slip circle

Procedia PDF Downloads 165

Authors: Andreas Kohlhepp, Gerrit Schatte, Wieland Christoph, Spliethoff Hartmut

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In recent years the research of heat transfer phenomena of water and other working fluids near the critical point experiences a growing interest for power engineering applications. To match the highly volatile characteristics of renewable energies, conventional power plants need to shift towards flexible operation. This requires speeding up the load change dynamics of steam generators and their heating surfaces near the critical point. In dynamic load transients, both a high heat flux with an unfavorable ratio to the mass flux and a high difference in fluid and wall temperatures, may cause problems. It may lead to deteriorated heat transfer (at supercritical pressures), dry-out or departure from nucleate boiling (at subcritical pressures), all cases leading to an extensive rise of temperatures. For relevant technical applications, the heat transfer coefficients need to be predicted correctly in case of transient scenarios to prevent damage to the heated surfaces (membrane walls, tube bundles or fuel rods). In transient processes, the state of the art method of calculating the heat transfer coefficients is using a multitude of different steady-state correlations for the momentarily existing local parameters for each time step. This approach does not necessarily reflect the different cases that may lead to a significant variation of the heat transfer coefficients and shows gaps in the individual ranges of validity. An algorithm was implemented to calculate the transient behavior of steam generators during load changes. It is used to assess existing correlations for transient heat transfer calculations. It is also desirable to validate the calculation using experimental data. By the use of a new full-scale supercritical thermo-hydraulic test rig, experimental data is obtained to describe the transient phenomena under dynamic boundary conditions as mentioned above and to serve for validation of transient steam generator calculations. Aiming to improve correlations for the prediction of the onset of deteriorated heat transfer in both, stationary and transient cases the test rig was specially designed for this task. It is a closed loop design with a directly electrically heated evaporation tube, the total heating power of the evaporator tube and the preheater is 1MW. To allow a big range of parameters, including supercritical pressures, the maximum pressure rating is 380 bar. The measurements contain the most important extrinsic thermo-hydraulic parameters. Moreover, a high geometric resolution allows to accurately predict the local heat transfer coefficients and fluid enthalpies.

Keywords: departure from nucleate boiling, deteriorated heat transfer, dryout, supercritical working fluid, transient operation of steam generators

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Authors: Carlos Caro, Ernest Bladé, Pedro Acosta, Camilo Lesmes

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The drying-wet process is one of the topics to be more careful in distributed hydrological modeling using finite volume schemes as a means of solving the equations of Saint Venant. In a hydrologic and hydraulic computer model, surface flow phenomena depend mainly on the different flow accumulation and subsequent runoff generation. These accumulations are generated by routing, cell by cell, from the heights of water, which begin to appear due to the rain at each instant of time. Determine when it is considered a dry cell and when considered wet to include in the full calculation is an issue that directly affects the quantification of direct runoff or generation of flow at the end of a zone of contribution by accumulations flow generated from cells or finite volume.

Keywords: hydrology, transport processes, hydrological modelling, finite volume schemes

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Authors: Norshazmira Mat Azmi, Sayidal El Fatimah Masnan, Shatirah Akib

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More than 70% of the Earth is covered by oceans, which are considered to possess boundless renewable energy, such as tidal energy, tidal current energy, wave energy, thermal energy, and chemical energy. The hybrid system help in improving the economic and environmental sustainability of renewable energy systems to fulfill the energy demand. The concept of hybridizing renewable energy is to meet the desired system requirements, with the lowest value of the energy cost. This paper propose a hybrid power generation system suitable for remote area application and highlight the impact of surface waves on turbine design and performance, and the importance of understanding the site-specific wave conditions.

Keywords: marine current energy, tidal turbines, wave turbine, renewable energy, surface waves, hydraulic flume experiments, instantaneous wave phase

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Authors: Paulinus W. Ihuah, Iyenemi Ibimina Kakulu, Victor A. Akujuru

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The development of the residential property is very expensive in Nigeria, especially as it is observed in Port Harcourt, although it is also investment costly in the other cities of Nigeria. The costly development nature incidentally reasons to the high deficits in residential property availability and affordability for the low-income people. Therefore, the main purpose of this paper is to provide sustainable accommodation design, which should improve residential property expensiveness and shortages for the low-income people. This is achieved through investigation of the tangible requirements and needs of the end-user of the property (low-income people), which thereafter would enhance sustainable and affordable residential property accommodation design for the end-users. Both the quantitative and qualitative instruments of data collection were utilised. The quantitative instrument via questionnaires was designed to examine the real needs and r requirement of the low-income people. However, the qualitative instrument via structured interview was espoused for the gathering of professionals’ opinions on the three predicted sustainable accommodation design alternatives. The analysis employed content analysis parameters, which offered a sustainable accommodation design and designed alternatives minimises costs and environmental impacts whereas exploiting the social satisfaction in residential accommodation developments. The finding underscores that sustainable accommodation design and development is practicable in Nigeria, so that cost of residential accommodation provided through this system is cheap to the low-income people. Further, erection of multi-storey residential accommodation units such as bedsit structure by utilising the concrete frame structure and building the internal and external walls with hollow concrete blocks within areas 60-130 square meters is encouraged. This paper philosophy indicates that by using sustainable accommodation design practices in Nigeria, improvements in the costs and shortages of residential accommodation can be attained for low-income people. However, policies support the government cannot be overemphasised for proper implementation of the suggested scheme.

Keywords: sustainable accommodation, housing design, residential property, low-income people

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Authors: Keyvan Ramin

Abstract:

The geometric nonlinearity of Off-Diagonal Bracing System (ODBS) could be a complementary system to covering and extending the nonlinearity of reinforced concrete material. Finite element modeling is performed for flexural frame, x-braced frame and the ODBS braced frame system at the initial phase. Then the different models are investigated along various analyses. According to the experimental results of flexural and x-braced frame, the verification is done. Analytical assessments are performed in according to three-dimensional finite element modeling. Non-linear static analysis is considered to obtain performance level and seismic behavior, and then the response modification factors calculated from each model’s pushover curve. In the next phase, the evaluation of cracks observed in the finite element models, especially for RC members of all three systems is performed. The finite element assessment is performed on engendered cracks in ODBS braced frame for various time steps. The nonlinear dynamic time history analysis accomplished in different stories models for three records of Elcentro, Naghan, and Tabas earthquake accelerograms. Dynamic analysis is performed after scaling accelerogram on each type of flexural frame, x-braced frame and ODBS braced frame one by one. The base-point on RC frame is considered to investigate proportional displacement under each record. Hysteresis curves are assessed along continuing this study. The equivalent viscous damping for ODBS system is estimated in according to references. Results in each section show the ODBS system has an acceptable seismic behavior and their conclusions have been converged when the ODBS system is utilized in reinforced concrete frame.

Keywords: FEM, seismic behaviour, pushover analysis, geometric nonlinearity, time history analysis, equivalent viscous damping, passive control, crack investigation, hysteresis curve

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Authors: Mirco Tarozzi, Giacomo Pignagnoli, Andrea Benedetti

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The design of planning maintenance of civil structures often requires the evaluation of their level of safety in order to be able to choose which structure, and in which measure, it needs a structural retrofit. This work deals with the evaluation of the stiffness reduction of a scaled steel deck due to the presence of localized damages. The dynamic tests performed on it have shown the variability of its main frequencies linked to the gradual reduction of its rigidity. This deck consists in a steel grillage of four secondary beams and three main beams linked to a concrete slab. This steel deck is 6 m long and 3 m wide and it rests on two abutments made of concrete. By processing the signals of the accelerations due to a random excitation of the deck, the main natural frequencies of this bridge have been extracted. In order to assign more reliable parameters to the numerical model of the deck, some load tests have been performed and the mechanical property of the materials and the supports have been obtained. The two external beams have been cut at one third of their length and the structural strength has been restored by the design of a bolted plate. The gradual loss of the bolts and the plates removal have made the simulation of localized damage possible. In order to define the relationship between frequency variation and loss in stiffness, the identification of its natural frequencies has been performed, before and after the occurrence of the damage, corresponding to each step. The study of the relationship between stiffness losses and frequency shifts has been reported in this paper: the square of the frequency variation due to the presence of the damage is proportional to the ratio between the rigidities. This relationship can be used to quantify the loss in stiffness of a real scale bridge in an efficient way.

Keywords: damage detection, dynamic test, frequency shifts, operational modal analysis, steel bridge

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Authors: Barbara Behre, Verolien Cauberghe, Dieneke Van de Sompel

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Sustainable consumption is on the rise, yet it has still not entered the mainstream in several industries, such as the fashion industry. In online fashion contexts, sustainability cues have been used to signal the sustainable benefits of certain garments to promote sustainable consumption. These sustainable cues may focus on the ecological or social dimension of sustainability. Since sustainability, in general, relates to distant, abstract benefits, the current study aims to examine if and how psychological distance may mediate the effects of exposure to different sustainability cues on consumption outcomes. Following the framework of Construal Level Theory of Psychological Distance, reduced psychological distance renders the construal level more concrete, which may influence attitudes and subsequent behavior in situations like fashion shopping. Most studies investigated sustainability as a composite, failing to differentiate between ecological and societal aspects of sustainability. The few studies examining sustainability more in detail uncovered that environmental sustainability is rather perceived in abstract cognitive construal, whereas social sustainability is linked to concrete construal. However, the construal level affiliation of the sustainability dimensions likely is not universally applicable to different domains and stages of consumption, which further suggest a need to clarify the relationships between environmental and social sustainability dimensions and the construal level of psychological distance within fashion brand consumption. While psychological distance and construal level have been examined in the context of sustainability, these studies yielded mixed results. The inconsistent findings of past studies might be due to the context-dependence of psychological distance as inducing construal differently in diverse situations. Especially in a hedonic consumption context like online fashion shopping, the role of visual processing of information could determine behavioural outcomes as linked to situational construal. Given the influence of the mode of processing on psychological distance and construal level, the current study examines the moderating role of verbal versus non-verbal presentation of the sustainability cues. In a 3 (environmental sustainability vs. social sustainability vs. control) x 2 (non-verbal message vs. verbal message) between subjects experiment, the present study thus examines how consumers evaluate sustainable brands in online shopping contexts in terms of psychological distance and construal level, as well as the impact on brand attitudes and buying intentions. The results among 246 participants verify the differential impact of the sustainability dimensions on fashion brand purchase intent as mediated by construal level and perceived psychological distance. The ecological sustainability cue is perceived as more concrete, which might be explained by consumer bias induced by the predominance of pro-environmental sustainability messages. The verbal versus non-verbal presentation of the sustainability cue neither had a significant influence on distance perceptions and construal level nor on buying intentions. This study offers valuable contributions to the sustainable consumption literature, as well as a theoretical basis for construal-level framing as applied in sustainable fashion branding.

Keywords: construal level theory, environmental vs social sustainability, online fashion shopping, sustainable fashion

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Authors: Manal A. Mohsen, Ahmed Tawfik

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Hydrogen production from cake wastewater by anaerobic dark fermentation via upflow anaerobic staged reactor (UASR) was investigated in this study. The reactor was continuously operated for four months at constant hydraulic retention time (HRT) of 21.57 hr, PH value of 6 ± 0.6, temperature of 21.1°C, and organic loading rate of 2.43 gCOD/l.d. The hydrogen production was 5.7 l H₂/d and the hydrogen yield was 134.8 ml H₂ /g COD_removed. The system showed an overall removal efficiency of TCOD, TBOD, TSS, TKN, and Carbohydrates of 40 ± 13%, 59 ± 18%, 84 ± 17%, 28 ± 27%, and 85 ± 15% respectively during the long term operation period. Based on the available results, the system is not sufficient for the effective treatment of cake wastewater, and the effluent quality of UASR is not complying for discharge into sewerage network, therefore a post treatment is needed (not covered in this study).

Keywords: cake wastewater industry, chemical oxygen demand (COD), hydrogen production, up-flow anaerobic staged reactor (UASR)

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Authors: Nachtane Mourad, Tarfaoui Mostapha, Saifaoui Dennoun, El Moumen Ahmed

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The current energy policy recommends the subject of energy efficiency and to phase out fossil energy as a master question for the prospective years. The kingdom requires restructuring its power equipment by improving the percentage of renewable energy supply and optimizing power systems and storage. Developing energy efficiency, therefore, obliges as a consubstantial objection to reducing energy consumption. The objective of this work is to show the energy transition in Morocco towards renewable energies, in particular, to show the great potential of renewable marine energies in Morocco, This goes back to the advantages of cost and non-pollution in addition to that of the independence of fossil energies. Bearing in mind the necessity of the balance of the Moroccan energy mix, hydraulic and thermal power plants have also been installed which will be added to the power stations already established as a prospect for a balanced network that is flexible to fluctuate demand.

Keywords: renewable marine energy, energy transition, efficiency energy, renewable energy

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Authors: Amol Lanke, Hadi Hoseinie, Behzad Ghodrati

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OEE has been used in many industries as measure of performance. However due to limitations of original OEE, it has been modified by various researchers. OEE for mining application is special version of classic equation, carries these limitation over. In this paper it has been aimed to modify the OEE for mining application by introducing the weights to the elements of it and termed as Mine Production index (MPi). As a special application of new index MPi shovel has been developed by team of experts and researchers for evaluating the shovel effectiveness. Based on analysis, utilization followed by performance and availability were ranked in this order. To check the applicability of this index, a case study was done on four electrical and one hydraulic shovel in a Swedish mine. The results shows that MPishovelcan properly evaluate production effectiveness of shovels and determine effectiveness values in optimistic view compared to OEE. MPi with calculation not only give the effectiveness but also can predict which elements should be focused for improving the productivity.

Keywords: mining, overall equipment efficiency (OEE), mine production index, shovels

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Authors: Alok Madan, Arshad K. Hashmi

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The paper presents a plastic analysis procedure based on the energy balance concept for performance based seismic retrofit of multi-story multi-bay masonry infilled reinforced concrete (R/C) frames with a ‘soft’ ground story using passive energy dissipation (PED) devices with the objective of achieving a target performance level of the retrofitted R/C frame for a given seismic hazard level at the building site. The proposed energy based plastic analysis procedure was employed for developing performance based design (PBD) formulations for PED devices for a simulated application in seismic retrofit of existing frame structures designed in compliance with the prevalent standard codes of practice. The PBD formulations developed for PED devices were implemented for simulated seismic retrofit of a representative code-compliant masonry infilled R/C frame with a ‘soft’ ground story using friction dampers as the PED device. Non-linear dynamic analyses of the retrofitted masonry infilled R/C frames is performed to investigate the efficacy and accuracy of the proposed energy based plastic analysis procedure in achieving the target performance level under design level earthquakes. Results of non-linear dynamic analyses demonstrate that the maximum inter-story drifts in the masonry infilled R/C frames with a ‘soft’ ground story that is retrofitted with the friction dampers designed using the proposed PBD formulations are controlled within the target drifts under near-field as well far-field earthquakes.

Keywords: energy methods, masonry infilled frame, near-field earthquakes, seismic protection, supplemental damping devices

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Authors: H. Zedira, M. T. Hannachi, H. Djebaili, B. Daheche

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The rapid pace of technology development and strong competition in the market, prompted us to consider the field of manufacturing of steel pipes by a process complies fully with the requirements of industrial induction welding is high frequency (HF), this technique is better known today in Algeria, more precisely for the manufacture of tubes diameters Single Annabib TG Tebessa. The aim of our study is based on the characterization of processes controlling the mechanical behavior of steel pipes (type E24-2), welded by high frequency induction, considering the different tests and among the most destructive known test internal pressure. The internal pressure test is performed according to the application area of welded pipes, or as leak test, either as a test of strength (bursting). All tubes are subjected to a hydraulic test pressure of 50 bar kept at room temperature for a period of 6 seconds. This study provides information that helps optimize the design and implementation to predict the behavior of the tubes during operation.

Keywords: castem, pressure, stress, tubes, thickness

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Authors: Mustapha Kamel Mihoubi, Reda Madi

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The problem of natural disasters in general and flooding in particular is a topic which marks a memorable action in the world and specifically in cities and large urban areas. Torrential floods and faster flows pose a major problem in urban area. Indeed, a better management of risks of floods becomes a growing necessity that must mobilize technical and scientific means to curb the adverse consequences of this phenomenon, especially in the Saharan cities in arid climate. The aim of this study is to deploy a basic calculation approach based on a hydrologic and hydraulic quantification for locating the black spots in urban areas generated by the flooding and to locate the areas that are vulnerable to flooding. The principle of flooding method is applied to the city of Ghardaia to identify vulnerable areas to inundation and to establish maps management and prevention against the risks of flooding.

Keywords: Alea, Beni Mzab, cartography, HEC-RAS, inundation, torrential, vulnerability, wadi

Procedia PDF Downloads 311

Authors: Lingfeng Wang, Zhipeng Chen, Shuang Qiu, Shijian Ge

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The effects of wastewater, with four different nutrient loadings, from synthetic centrate on biomass production of Chlorella vulgaris, nutrient removal, microalgal settling, and lipid production were investigated in photobioreactors under both batches and, subsequently, semi-continuous operations. At higher centrate concentration factors (17.2% and 36.2%), hydraulic retention time and pH adjustments could be employed to sustain acceptable microalgal growth rates and wastewater treatment. Similar nutrient removals efficiencies (>95%) and biomass production (0.42-0.51 g/L) were observed for the four centrate concentrations. Both the lipid productivity and lipid content decreased with increasing nutrient loading in the wastewater. The results also demonstrated that the mass ratio of carbohydrate to protein could provide a good indication of microalgal settling performance, rather than sole component composition or total extracellular polymeric substances.

Keywords: lipid production, microalgae, nutrient removal, wastewater

Procedia PDF Downloads 240

Authors: Ririt Aprilin Sumarsono

Abstract:

Composite member (concrete and steel) has been widely advanced for structural utilization due to its best performance in resisting load, reducing the total weight of the structure, increasing stiffness, and other available advantages. On the other hand, the environment load such as corrosion (e.g. chloride ingress) creates significant time-dependent degradation for steel. Analysis performed in this paper is mainly considered uniform corrosion for evaluating the composite beam without examining the pit corrosion as the initial corrosion formed. Corrosion level in terms of weight loss is modified in yield stress and modulus elasticity of steel. Those two mechanical properties are utilized in this paper for observing the stresses due to corrosion attacked. As corrosion level increases, the effective width of the composite beam in the concrete section will be wider. The position of a neutral axis of composite section will indicate the composite action due to corrosion of composite beam so that numerous shear connectors provided must be reconsidered. Flexure capacity quantification provides stresses, and shear capacity calculation derives connectors needed in overcoming the shear problem for composite beam under corrosion. A model of simply supported composite beam examined in this paper under uniform corrosion where the stresses as the focus of the evaluation. Principal stress at the first stage of composite construction decline as the corrosion level incline, parallel for the second stage stress analysis where the tension region held by the steel undergoes lower capacity due to corrosion. Total stresses of the composite section for steel to be born significantly decreases particularly in the outermost fiber of tension side. Whereas, the available compression side is smaller as the corrosion level increases so that the stress occurs on the compression side shows reduction as well. As a conclusion, the increment of corrosion level will degrade both compression and tension side of stresses.

Keywords: composite beam, modulus of elasticity, stress analysis, yield strength, uniform corrosion

Procedia PDF Downloads 286

Authors: J. Martin Leal-Graciano, Juan J. Pérez-Gavilán, A. Reyes-Salazar, J. H. Castorena, J. L. Rivera-Salas

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The experimental results about the global behavior of twelve 1:2 scaled reinforced concrete frame subject to in-plane lateral load are presented. The main objective was to generate experimental evidence about the use of steel bars within mortar bed-joints as shear reinforcement in infill walls. Similar to the Canadian and New Zealand standards, the Mexican code includes specifications for this type of reinforcement. However, these specifications were obtained through experimental studies of load-bearing walls, mainly confined walls. Little information is found in the existing literature about the effects of joint reinforcement on the seismic behavior of infill masonry walls. Consequently, the Mexican code establishes the same equations to estimate the contribution of joint reinforcement for both confined walls and infill walls. A confined masonry construction and a reinforced concrete frame infilled with masonry walls have similar appearances. However, substantial differences exist between these two construction systems, which are mainly related to the sequence of construction and to how these structures support vertical and lateral loads. To achieve the objective established, ten reinforced concrete frames with masonry infill walls were built and tested in pairs, having both specimens in the pair identical characteristics except that one of them included joint reinforcement. The variables between pairs were the type of units, the size of the columns of the frame and the aspect ratio of the wall. All cases included tie-columns and tie-beams on the perimeter of the wall to anchor the joint reinforcement. Also, two bare frame with identical characteristic to the infilled frames were tested. The purpose was to investigate the effects of the infill wall on the behavior of the system to in-plane lateral load. In addition, the experimental results were compared with the prediction of the Mexican code. All the specimens were tested in cantilever under reversible cyclic lateral load. To simulate gravity load, constant vertical load was applied on the top of the columns. The results indicate that the contribution of the joint reinforcement to lateral strength depends on the size of the columns of the frame. Larger size columns produce a failure mode that is predominantly a sliding mode. Sliding inhibits the production of new inclined cracks, which are necessary to activate (deform) the joint reinforcement. Regarding the effects of joint reinforcement in the performance of confined masonry walls, many facts were confirmed for infill walls: this type of reinforcement increases the lateral strength of the wall, produces a more distributed cracking and reduces the width of the cracks. Moreover, it reduces the ductility demand of the system at maximum strength. The prediction of the lateral strength provided by the Mexican code is property in some cases; however, the effect of the size of the columns on the contribution of joint reinforcement needs to be better understood.

Keywords: experimental study, Infill wall, Infilled frame, masonry wall

Procedia PDF Downloads 77

Authors: Houmame Benbouali

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The risks, in general, exist in any project; one can hardly carry out a project without taking risks. The hydraulic works are rather complex projects in their design, realization and exploitation, and are often subjected at the multiple risks being able to influence with their good performance, and can have an negative impact on their environment. The present study was carried out to quote the impacts caused by purification plant STEP Chlef on the environment, it aims has studies the environmental impacts during construction and when designing this STEP, it is divided into two parts: The first part results from a research task bibliographer which contain three chapters (-cleansing of water worn-general information on water worn-proceed of purification of waste water). The second part is an experimental part which is divided into four chapters (detailed state initial-description of the station of purification-evaluation of the impacts of the project analyzes measurements and recommendations).

Keywords: treatment plant, waste water, waste water treatment, environmental impact

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Authors: I. Kruashvili, I. Inashvili, K. Bziava, M. Lomishvili

Abstract:

Seepage capillary anomalies in the active layer of soil, related to the soil water movement, often cause variation of soil hydrophysical properties and become one of the main objectives of the hydroecology. It is necessary to mention that all existing equations for computing the seepage flow particularly from soil channels, through dams, bulkheads, and foundations of hydraulic engineering structures are preferable based on the linear seepage law. Regarding the existing beliefs, anomalous seepage is based on postulates according to which the fluid in free volume is characterized by resistance against shear deformation and is presented in the form of initial gradient. According to the above-mentioned information, we have determined: Equation to calculate seepage coefficient when the velocity of transition flow is equal to seepage flow velocity; by means of power function, equations for the calculation of average and maximum velocities of seepage flow have been derived; taking into consideration the fluid continuity condition, average velocity for calculation of average velocity in capillary tube has been received.

Keywords: seepage, soil, velocity, water

Procedia PDF Downloads 462

Authors: J. Martin Leal-Graciano, Juan J. Pérez-Gavilán, A. Reyes-Salazar, J. H. Castorena, J. L. Rivera-Salas

Abstract:

The experimental results about the global behavior of twelve 1:2 scaled reinforced concrete frames subject to in-plane lateral load are presented. The main objective was to generate experimental evidence about the use of steel bars within mortar bed joints as shear reinforcement in infill walls. Similar to the Canadian and New Zealand standards, the Mexican code includes specifications for this type of reinforcement. However, these specifications were obtained through experimental studies of load-bearing walls, mainly confined walls. Little information is found in the existing literature about the effects of joint reinforcement on the seismic behavior of infill masonry walls. Consequently, the Mexican code establishes the same equations to estimate the contribution of joint reinforcement for both confined walls and infill walls. Confined masonry construction and a reinforced concrete frame infilled with masonry walls have similar appearances. However, substantial differences exist between these two construction systems, which are mainly related to the sequence of construction and to how these structures support vertical and lateral loads. To achieve the objective established, ten reinforced concrete frames with masonry infill walls were built and tested in pairs, having both specimens in the pair identical characteristics except that one of them included joint reinforcement. The variables between pairs were the type of units, the size of the columns of the frame, and the aspect ratio of the wall. All cases included tie columns and tie beams on the perimeter of the wall to anchor the joint reinforcement. Also, two bare frames with identical characteristics to the infilled frames were tested. The purpose was to investigate the effects of the infill wall on the behavior of the system to in-plane lateral load. In addition, the experimental results were compared with the prediction of the Mexican code. All the specimens were tested in a cantilever under reversible cyclic lateral load. To simulate gravity load, constant vertical load was applied on the top of the columns. The results indicate that the contribution of the joint reinforcement to lateral strength depends on the size of the columns of the frame. Larger size columns produce a failure mode that is predominantly a sliding mode. Sliding inhibits the production of new inclined cracks, which are necessary to activate (deform) the joint reinforcement. Regarding the effects of joint reinforcement in the performance of confined masonry walls, many facts were confirmed for infill walls. This type of reinforcement increases the lateral strength of the wall, produces a more distributed cracking, and reduces the width of the cracks. Moreover, it reduces the ductility demand of the system at maximum strength. The prediction of the lateral strength provided by the Mexican code is a property in some cases; however, the effect of the size of the columns on the contribution of joint reinforcement needs to be better understood.

Keywords: experimental study, infill wall, infilled frame, masonry wall

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Authors: Mahmoud Y. M. Ahmed, Ahmed Konsowa, Mostafa Sami, Ayman Mosallam

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Fukushima nuclear accident (Japan 2011) has drawn attention to the issue of gas leakage from hazardous facilities through building boundaries. The rapidly increasing investments in nuclear stations have made the ability to predict, and prevent, gas leakage a rather crucial issue both environmentally and economically. Leakage monitoring for underground facilities is rather complicated due to the combination of Reinforced Concrete Shear Wall (RCSW) and soil. In the framework of a recent research conducted by the authors, the gas insulation capabilities of RCSW-soil combination have been investigated via a lab-scale experimental work. Despite their accuracy, experimental investigations are expensive, time-consuming, hazardous, and lack for flexibility. Numerically simulating the gas leakage as a fluid flow problem based on Computational Fluid Dynamics (CFD) modeling approach can provide a potential alternative. This novel implementation of CFD approach is the topic of the present paper. The paper discusses the aspects of modeling the gas flow through porous media that resemble the RCSW both isolated and combined with the normal soil. A commercial CFD package is utilized in simulating this fluid flow problem. A fixed RCSW layer thickness is proposed, air is taken as the leaking gas, whereas the soil layer is represented as clean sand with variable properties. The variable sand properties include sand layer thickness, fine fraction ratio, and moisture content. The CFD simulation results almost demonstrate what has been found experimentally. A soil layer attached next to a cracked reinforced concrete section plays a significant role in reducing the gas leakage from that cracked section. This role is found to be strongly dependent on the soil specifications.

Keywords: RCSW, gas leakage, Pressure Decay Method, hazardous underground facilities, CFD

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Authors: Alexandre Daliberto Frugoli, Pedro Jose Gabriel Ferreira, Pedro Americo Frugoli, Lucio Leonardo, Thais Cavalheri Santos

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Laboratory classes in Engineering courses are essential for students to be able to integrate theory with practical reality, by handling equipment and observing experiments. In the researches of physical phenomena, students can learn about the complexities of science. Over the past years, universities in developing countries have been reducing the course load of engineering courses, in accordance with cutting cost agendas. Quality education is the object of study for researchers and requires educators and educational administrators able to demonstrate that the institutions are able to provide great learning opportunities at reasonable costs. Didactic test benches are indispensable equipment in educational activities related to turbo hydraulic pumps and pumping facilities study, which have a high cost and require long class time due to measurements and equipment adjustment time. In order to overcome the aforementioned obstacles, aligned with the professional objectives of an engineer, GruPEFE - UNIP (Research Group in Physics Education for Engineering - Universidade Paulista) has developed a multi-purpose stand for the discipline of fluid mechanics which allows the study of velocity and flow meters, loads losses and pump association. In this work, results obtained by the association in series and in parallel of hydraulic pumps will be presented and discussed, mainly analyzing the repeatability of experimental procedures and their agreement with the theory. For the association in series two identical pumps were used, consisting of the connection of the discharge of a pump to the suction of the next one, allowing the fluid to receive the power of all machines in the association. The characteristic curve of the set is obtained from the curves of each of the pumps, by adding the heads corresponding to the same flow rates. The same pumps were associated in parallel. In this association, the discharge piping is common to the two machines together. The characteristic curve of the set was obtained by adding to each value of H (head height), the flow rates of each pump. For the tests, the input and output pressure of each pump were measured. For each set there were three sets of measurements, varying the flow rate in range from 6.0 to 8.5 m 3 / h. For the two associations, the results showed an excellent repeatability with variations of less than 10% between sets of measurements and also a good agreement with the theory. This variation agrees with the instrumental uncertainty. Thus, the results validate the use of the fluids bench designed for didactic purposes. As a future work, a digital acquisition system is being developed, using differential sensors of extremely low pressures (2 to 2000 Pa approximately) for the microcontroller Arduino.

Keywords: engineering education, fluid mechanics, hydrostatic pumps association, multi-purpose stand

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Authors: Wojciech Dąbrowski, Joanna Bąk, Laurent Solliec

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Nowadays technical and technological progress and constant development of methods and devices applied to sanitary engineering is indispensable. Issues related to sanitary engineering involve flow measurements for water and wastewater. The precise measurement is very important and pivotal for further actions, like monitoring. There are many methods and techniques of flow measurement in the area of sanitary engineering. Weirs and flumes are well–known methods and common used. But also there are alternative methods. Some of them are very simple methods, others are solutions using high technique. The old–time method combined with new technique could be more useful than earlier. Paper describes substitute method of flow gauging (California pipe method) and proposal of modification of this method used for inclined pipe. Examination of possibility of improving and developing old–time methods is direction of the investigation.

Keywords: California pipe, sewerage, flow rate measurement, water, wastewater, improve, modification, hydraulic monitoring, stream

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Authors: Iman Mazinani, Zubaidah Ismail, Ahmad Mustafa Hashim, Amir Reza Saba

Abstract:

Two tragic tsunamis that devastated the west coast of Sumatra Island, Indonesia in 2004 and North East Japan in 2011 had damaged bridges to various extents. Tsunamis have resulted in the catastrophic deterioration of infrastructures i.e. coastal structures, utilities and transportation facilities. A bridge structure performs vital roles to enable people to perform activities related to their daily needs and for development. A damaged bridge needs to be repaired expeditiously. In order to understand the effects of tsunami forces on bridges, experimental tests are carried out to measure the characteristics of hydrodynamic force at various wave heights. Coastal bridge models designed at a 1:40 scale are used in a 24.0 m long hydraulic flume with a cross section of 1.5 m by 2.0 m. The horizontal forces and uplift forces in all cases show that forces increase nonlinearly with increasing wave amplitude.

Keywords: tsunami, bridge, horizontal force, uplift force

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Authors: Çiğdem Avcı Karataş

Abstract:

Mitigation of structural damage caused by earthquake and reduction of fatality is one of the main concerns of engineers in seismic prone zones of the world. To achieve this aim many technologies have been developed in the last decades and applied in construction and retrofit of structures. On the one hand Turkey is well-known a country of high level of seismicity; on the other hand steel-composite structures appear competitive today in this country by comparison with other types of structures, for example only-steel or concrete structures. Composite construction is the dominant form of construction for the multi-storey building sector. The reason why composite construction is often so good can be expressed in one simple way - concrete is good in compression and steel is good in tension. By joining the two materials together structurally these strengths can be exploited to result in a highly efficient design. The reduced self-weight of composite elements has a knock-on effect by reducing the forces in those elements supporting them, including the foundations. The floor depth reductions that can be achieved using composite construction can also provide significant benefits in terms of the costs of services and the building envelope. The scope of this paper covers analysis, materials take-off, cost analysis and economic comparisons of a multi-storey building with composite and steel frames. The aim of this work is to show that designing load carrying systems as composite is more economical than designing as steel. Design of the nine stories building which is under consideration is done according to the regulation of the 2007, Turkish Earthquake Code and by using static and dynamic analysis methods. For the analyses of the steel and composite systems, plastic analysis methods have been used and whereas steel system analyses have been checked in compliance with EC3 and composite system analyses have been checked in compliance with EC4. At the end of the comparisons, it is revealed that composite load carrying systems analysis is more economical than the steel load carrying systems analysis considering the materials to be used in the load carrying system and the workmanship to be spent for this job.

Keywords: composite analysis, earthquake, steel, multi-storey building

Procedia PDF Downloads 571

Authors: Muhammad Afief Maruf

Abstract:

Kacapuri foundation is the traditional shallow foundation of building which has been used since long by traditional communities in Borneo, Indonesia. Kacapuri foundation is a foundation that uses a combination of ironwood (eusideroxylon zwageri) as a column and truss and softwood (Melaleuca leucadendra syn. M. leucadendron) as a raft. In today's modern era, ironwood happened to be a rare item, and it is protected by the Indonesian government. This condition then triggers the idea to maintain the shape of the traditional foundation by modifying the material. The suggestion is replacing the ironwood column with reinforced concrete column. In addition, the number of stem softwood is added to sustain the burden of replacing the column material. Although this modified form of Kacapuri foundation is currently still not been tested in applications in society, some research on the modified Kacapuri foundation has been conducted by some researchers and government unit. This paper will try to give an overview of the theoretical foundation bearing capacity Kacapuri modifications applied to the soft alluvial soil located in Borneo, Indonesia, where the original form of Kacapuri is implemented this whole time. The foundation is modeled buried depth in 2m below the ground surface and also below the ground water level. The calculation of the theoretical bearing capacity and then is calculated based on the bearing capacity equation suggested Skempton, Terzaghi and Ohsuki using the data of soft alluvial soil in Borneo. The result will then compared with the bearing capacity of the Kacapuri foundation original design from some previous research. The results show that the ultimate bearing capacity of the Modified Kacapuri foundation using Skempton equation amounted to 329,26 kN, Terzaghi for 456,804kN, and according Ohsaki amounted to 491,972 kN. The ultimate bearing capacity of the original Kacapuri foundation model based on Skempton equation is 18,23 kN. This result shows that the modification added the ultimate bearing capacity of the foundation, although the replacement of ironwood to reinforced concrete will also add some dead load to the total load itself.

Keywords: bearing capacity, Kacapuri, modified foundation, shallow foundation

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Authors: K. Harrat, M. Hidjeb, M. T’kint

Abstract:

The aim of the present research work is to characterize a cement palm date fiber composite in order to be used in isolation and in the manufacture of new structural materials. This technique may possibly participate seriously in the preservation of the environment and develop a growing need for plant products. On one hand, It has been shown that the presence of natural fiber in the composite materials manufacture, based on hydraulic binder, has improved the mechanical behaviour of the material. On the Other hand, It has been proven that the durability of composite materials reinforced with untreated fibers was largely affected by the presence of organic matter. In order to extract the organic material, the fibers were treated with boiling water and then coated with different types of products. A considerable improvement in the sensitivity to water of the fibers, as well as in the mechanical strength and in the ductility of the composite material was observed. The fiber being sensitive to water, the study put the emphasis on its dimensional stability.

Keywords: cement composite, durability, heat treatment, mechanical behaviour, vegetal fiber

Procedia PDF Downloads 454

Authors: Sergo Esadze

Abstract:

Seismic resistance norms require calculation of cantilevers on vertical components of the base seismic acceleration. Long span cantilevers, as a rule, must be calculated as a separate construction element. According to the architectural-planning solution, functional purposes and environmental condition of a designing buildings/structures, long span cantilever construction may be of very different types: both by main bearing element (beam, truss, slab), and by material (reinforced concrete, steel). A choice from these is always linked with bearing construction system of the building. Research of vertical seismic vibration of these constructions requires individual approach for each (which is not specified in the norms) in correlation with model of seismic load. The latest may be given both as deterministic load and as a random process. Loading model as a random process is more adequate to this problem. In presented paper, two types of long span (from 6m – up to 12m) reinforcement concrete cantilever beams have been considered: a) bearing elements of cantilevers, i.e., elements in which they fixed, have cross-sections with large sizes and cantilevers are made with haunch; b) cantilever beam with load-bearing rod element. Calculation models are suggested, separately for a) and b) types. They are presented as systems with finite quantity degree (concentrated masses) of freedom. Conditions for fixing ends are corresponding with its types. Vertical acceleration and vertical component of the angular acceleration affect masses. Model is based on assumption translator-rotational motion of the building in the vertical plane, caused by vertical seismic acceleration. Seismic accelerations are considered as random processes and presented by multiplication of the deterministic envelope function on stationary random process. Problem is solved within the framework of the correlation theory of random process. Solved numerical examples are given. The method is effective for solving the specific problems.

Keywords: cantilever, random process, seismic load, vertical acceleration

Procedia PDF Downloads 188

Authors: G. Kim, R. Sterkenburg

Abstract:

One of the disadvantages of honeycomb sandwich structure is that they are prone to fluid intrusion. The purpose of this study is to determine if the structural properties of honeycomb core are affected by contact with a fluid. The test specimens were manufactured of fiberglass prepreg for the facesheets and Nomex^® honeycomb core for the core material in accordance with ASTM C-365/365M. Test specimens were soaked in several different kinds of fluids, such as aircraft fuel, turbine engine oil, hydraulic fluid, and water for a period of 60 days. A flatwise compressive test was performed, and the test results were analyzed to determine how the contact with aircraft fluids affected the compressive strength of the Nomex^® honeycomb core and how the strength was recovered when the specimens were dry. In addition, the investigation of de-bonding between facesheet and core material after soaking were performed to support the study.

Keywords: sandwich structure, honeycomb, environmental degradation, debonding

Procedia PDF Downloads 176

Authors: Samih Ahmed, Guayente Minchot, Fritz King, Mikael Hallgren

Abstract:

The stress ribbon system has numerous advantages that include but are not limited to increasing overall stiffness, control deflections, and reduction of materials consumption, which in turn, reduces the load and the cost. Nevertheless, its use is usually limited to bridges, in particular, pedestrian bridges; this can be attributed to the insufficient space that buildings' usually have for end supports, and/or back- stayed cables, that can accommodate the expected high pull-out forces occurring at the cables' ends. In this work, the roof of Västerås Travel Center, which will become one of the longest cable suspended roofs in the world, was chosen as a case study. The aim was to investigate the optimal technique to model the post-tensioned stress ribbon system for the roof structure using the FEM software SAP2000 and to assess any possible reduction in the pull-out forces, deflections, and concrete stresses. Subsequently, a conventional cable suspended roof was simulated using SAP2000, and compared to the post-tension stress ribbon system in order to examine the potential of the latter. Moreover, the effects of temperature loads and support movements on the final design loads were examined. Based on the study, a few practical recommendations concerning the construction method and the iterative design process, required to meet the architectural geometrical demands, are stated by the authors. The results showed that the post-tensioned stress ribbon system reduces the concrete stresses, overall deflections, and more importantly, reduces the pull-out forces and the vertical reactions at both ends by up to 16% and 11%, respectively, which substantially reduces the design forces for the support structures. The magnitude of these reductions was found to be highly correlated to the applied prestressing force, making the size of the prestressing force a key factor in the design.

Keywords: cable suspended, post-tension, roof structure, SAP2000, stress ribbon

Procedia PDF Downloads 159