M.S. Theses

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AHP-based risk identification risk assessment and risk allocation approach for the micromobility sector
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Yemlihalıoğlu, Emir.; Yaşar, Ilgın.
In today’s world, where the micromobility sector, which is one of the most important sub-headings of the sharing economy model, in which people pay for the products and services they need for a short time, without owning them, is rapidly becoming widespread, many people and institutions are directly and indirectly affected by this situation. To minimize the negative effects and take the necessary precautions, the current situation should be revealed and the risks that may arise should be determined. After examining the sharing economy and risk allocation concepts, first of all, the risks arising from the micromobility sector were determined in this study. Afterward, the AHP method, which is one of the multi-criteria decision-making methods, was explained and the surveys prepared were evaluated by the experts, the determined risks were distributed among the alternatives, and the opportunity to guide and share responsibility for the applications to be made after that was provided. Based on this study, it was easier to determine the main topics for future research.
Risk assessment in the context of modern methods of construction leveraging data analytics
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Tatari, Ali.; Çomu, Semra.
As the construction industry moves towards more innovative, sustainable, and faster construction techniques, Modern Methods of Construction (MMC) has been regarded as a solution for meeting these demands. Nonetheless, under immense pressure, decision-makers' opposition caused by oblivious stakeholders makes for tenuous circumstances for innovation. Yet, the literature lacks a comprehensive approach for cost overruns risk assessment of implementing MMC. The study, therefore, aims to encourage the further take-up of offsite MMC in future projects of the housing sector by primarily soliciting opinions from experienced professionals. In achieving this endeavor, the study (1) identified and prioritized risk factors; (2) revealed the underlying categories; (3) proposed ways to prioritize risks; and lastly (4) developed an AI-based risk assessment model. Through the adoption of the generative adversarial networks, an Artificial Neural Networks (ANN) model will also be developed. Study findings revealed the significant dissimilar criticality levels of risk factors. The top seven most risky factors are Safety Hazards, Direct Costs, Poor Understanding, Quality Monitoring, Scheduling and Planning, Site Layout, and Machinery and Technology with an overall frequency of occurrence of 0.736, 0.733, 0.730, 0.725, 0.708, 0.705, and 0.702, respectively. The study brings to light the inadequacy of the current industry and indicates that future research opportunities lie in the adoption of MMC. The study adds value to the literature by exploring and capturing hidden trends and patterns related to conditional dependence between risk factors. The results aid the industry stakeholders to prioritize risk factors to develop risk response measures. Accordingly, decision-makers will be capable to distribute the contingency budget on more uncertain events, which will potentially facilitate achieving project objectives and avoid racking up substantial losses.
Investigating organizational learning in the Turkish construction companies
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Yelmen, Murat.; Özorhon, Beliz.
In a rapidly changing and complex environment, construction industry companies are looking for many different ways to gain competitive advantage and to show a sustainable presence in the future. Organizational learning is a process which ables companies to adapt to changing conditions, gain an advantage over their competitors, and increase their productivity. Organizational learning is defined as the process by which organizations alter or adjust their mental models, rules, procedures, or knowledge in order to maintain or enhance performance. In this thesis study, organizational learning in construction companies in Turkey has been examined by considering the deficiencies of the studies in the literature. The main approach taken in this study is to develop a framework based on a comprehensive literature review covering the concept of organizational learning in the construction sector from a holistic perspective, and then to use empirical research to investigate this framework. The proposed framework consists of 6 main factors and 53 sub-factors obtained based on in-depth literature review and expert opinions. These items were evaluated by the employees of construction companies through a questionnaire survey where 136 participants responded and the collected data were analyzed with descriptive statistics and Structural Equation Modeling (SEM). As a result, it has been revealed that companies see client requirements as a significant driver for learning, and companies learn most from the experiences of other companies and by acquiring new employees. It has been concluded that while individual and organizational training is seen as the distinct enabler factor for learning, the ambiguous goals is perceived as the most obvious barrier. It has been determined that the most significant effect of organizational learning is the increase in productivity, both as an impact on corporate level and as a benefit on a project level.
Experimental investigation of the response of buried pipelines to surficial loads
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Rogenbuke, Peter.; Çinicioğlu, Özer.; Bildik, Selçuk.
Buried pipes serve as the lifelines of modern cities and therefore have the utmost importance for today’s society. Owing to their buried state, it is not easy to detect damages; therefore, extra caution in their design is required to prevent irreparable damages. As deformation is generally caused by excessive stresses, one way to reduce the imposed stresses acting on the pipe is to use geosynthetic materials, since these materials reduce stresses on the pipe by distributing stresses more uniformly,at the same time increasing the bearing capacity of the soil. The critical parameters controlling the magnitude of stresses acting on the pipe are the burial depth, soil’s relative density, placement depth of geosynthetic layers, the number of geosynthetic layers and material properties of the pipe. For this purpose in this study, small- scale laboratory experiments were conducted ın a rigid box at 1g to observe the effects of these parametes on pipe stresses and the bearing capacity of the soil with and without a buried pipe. Strain gauges were used to record the pipe stresses, and backfill material of choice was sand. In the model experiments, a model footing was loaded until a pre-selected settlement threshold is reached. LVDT transducers and load cells were used to measure the settlement and load values, respectively. Resulting displacements are determined by analyzing consecutive photographs of the evolving tests using MATLAB based Particle Image Velocimetry (PIV) software. A total of 26 experiments were conducted, nine without geogrid reinforcements and the rest with geogrid reinforcements, at different relative densities. Obtained results are discussed in this work.
Identifying critical success factors for successful BIM-FM implementation in construction projects
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Özfurat, Bensu Namlı.; Çomu, Semra.
The use of BIM (Building Information Modeling) in FM (Facility Management) is becoming increasingly common around the world, but despite a large number of studies focusing on BIM implementation success in design and construction, there is still no consensus on how to evaluate BIM-FM integration success. The primary goal of this research is to identify and prioritize BIM-FM related CSFs and offer an Analytic Network Process (ANP) model to evaluate factors in construction projects carried out by Turkish contractors. Its purpose is to provide some guidance on how to make BIM-FM deployment more efficient. It also intends to acquire insights on the state of BIM-FM integration in Turkey from professionals working in the Turkish construction sector who are specialists in BIM-FM processes, as well as interpret the CSFs listed. To achieve these objectives, identified CSFs are grouped into stakeholders-related, technology-related, design-related, and handover process related factors. The focus group sessions are used to collect data on interrelationships and relative importance ratings. ANP is then used to compute the priorities and importance weights. “BIM education and training for employees”, “Top leadership backing and motivation”, “Availability of capable/experienced personnel (both in FM and AEC)”, “Early involvement of Facility Managers in the BIM process”, “Using BIM to maximize potential cost savings (return on investment of built assets)” success factors and “stakeholders related factors and “design process-related factors” groups are among the essential findings of this study. Interviews are used to evaluate the final CSFs list and obtain input on the current status of BIM-FM integration in the Turkish construction sector and assess the advantages and barriers to BIM-FM integration indicated in the literature. This model gave industry representatives a way to analyze the effectiveness of their BIM-FM integration. The suggested model’s findings may help FM and AEC organizations review their projects and take the required steps to ensure project success.
High volume fly ash concretes for sustainable applications in construction
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Balcı, Elifsu.; Zihnioğlu, Nilüfer Özyurt.; Özturan, Turan.
Reducing CO2 emission has become one of the most important subjects that the world focuses. Various actions are taken to make the construction materials and methods sustainable since the construction industry has a great contribution to the world's CO2 emissions. Replacement of cement with alternative binders is considered the most efficient and practical way to increase the sustainability of concrete. Fly ash usage in concrete has several effects for increasing sustainability. It decreases the use of cement and environmental pollution while it enhances some properties of concrete. Increased level of replacement further decreases environmental damage made by the production of concrete if targeted performance parameters could be obtained. In this study, the fresh properties, strength properties, and durability properties of different concrete mixtures were examined. The structural design of an industrial floor was made by using these ordinary concrete (PCC) and high- volume fly ash concrete (HVFAC), and the materials were compared by means of required thickness, environmental impact, and economic impact. Two replacement levels (40-60%) and two water/binder ratios (W/B) (0.35-0.50) were considered, and the mechanical properties of the mixtures were determined. Based on TR34, thickness design for an industrial floor was done for all concrete series. Environmental and economic impact analysis was done for all concrete series. Compared to PCC mixtures, lower mechanical properties, higher thickness requirements, and lower environmental impact values were found for HVFAC mixtures. With decreasing W/B, enhanced performance parameters were obtained for both PCC and HVFAC mixtures. The results of this study show that the environmental impact of concrete could be further decreased by increasing the replacement level of fly ash and still targeted performance parameters could be obtained from industrial floors.
An investigation on the effectivenss of nailed timber walls as retrofitting measure for substandard concrete structures
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Keser, Aslı.; Luş, Hilmi.; Ceccotti, Ario.
Turkey is in a seismically active region and has suffered through extensive losses due to several major earthquakes that struck its various parts. The destructive effects of earthquakes in Turkey are infuriated by the large volume of buildings constructed with low quality materials and workmanship. Especially a great percentage of residential buildings are constructed by using substandard concrete and reinforcement. Furthermore, research shows a great possibility of a high magnitude earthquake to occur in the near future around the Marmara region, which includes the most populated cities in Turkey. Inevitably, there is a need for an effective and affordable retrofitting method. In this study, a new retrofitting method is introduced and its effect on the seismic performance of two representative case study buildings are investigated. The retrofitting method consists of the implementation of timber walls which are prepared with nails. Initially, cyclic shear tests are performed on two types of nailed timber walls in an effort to obtain stiffness and strength properties. The only difference between the nailed timber walls is the number of nails used. Computational simulations of the experimental tests are generated in CSI Perform3D with buckling restrained brace elements. Two simulations of each case study reinforced concrete buildings retrofitted with the two types of nailed timber walls are conducted along with the original reinforced concrete building. Finally, the seismic performances of structural models are compared with each other. For the first case study building, which is a well-designed building with substandard material quality, it is concluded that even though the seismic performance of the representative building is slightly increased, a comprehensive enhancement in seismic performance is not achieved with the retrofitting method investigated. For the second case study building, which is a poorly designed building with low material quality, seismic performance is significantly improved.
Rapid seismic screening of reinforced concrete buildings using energy-based principles
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Darılmaz, Ahmet Mehdi.; Yalçın, Cem.
Seismic evaluation methods were developed and employed in seismic design codes for the purpose of avoiding life loss in the aftermath of earthquakes. The high death and economic toll from previous earthquakes highlight the importance of this eval uation for the residential structures in Turkey. However, the task of evaluation is challenging due to the abundance of structurally flawed buildings. Therefore, use of quick screening techniques is essential. Current rapid screening methods rely either on force or displacement-based approaches, which fail to employ some important pa rameters of earthquakes such as earthquake duration, frequency content, and energy dissipation capacity. Another approach which has been under development since the 1980s, the energy-based approach, was proven to be more successful in employing these parameters. Thus, the aim of this study is to develop a rapid seismic screening method for residential reinforced concrete structures that employs energy-based principles and evaluates the performance using the guidelines of the Turkish Seismic Code. A MAT LAB program, which executes a modified version of the energy-based design algorithm proposed by Yal¸cın et al. [1], was developed to conduct a parametric study related to the parameters determining the earthquake energy demand and energy dissipation capacity of structures. Additional parameters related to structural irregularities and deficiencies were also employed in this study. The results of the parametric study were subjected to statistical analyses to produce a simple model for estimating the damage score of the structures under various scenarios, which in turn was used to predict the performance level of the structures.
Evaluation of the environmental effects of connected autonomous vehicles in traffic incident scenarios on uninterrupted facilities
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Şahin, Rahmi.; Gökaşar, Ilgın.
Traffic incidents can occur due to both human errors and the inadequacy of road networks. These incidents can cause not only material damage but also loss of life. In case of an incident, it causes the vehicles in the traffic network to stay on the road longer and consume more fuel. The increase in fuel consumption increases the emission of CO2 (Carbon Dioxide), which is an effect of climate change. To reduce the negative effects of incidents on the environment, incident detection, and real-time traffic management methods are important. In this thesis, an uninterrupted road network was created utilizing SUMO traffic simulation to evaluate the environmental effects of incidents. This road network was evaluated over different scenarios with the integration of incident detection algorithms which are California and Standard Normal Deviation and real- time traffic management algorithms which are VSL and LCS. Environmental results were obtained by analyzing these different scenarios. Two types of vehicles were used: human- driven and connected autonomous vehicles. 11 different percentages of autonomous vehicles in increments of 10 from 0 to 100 were based on the research. It was seen that the increase in the use of connected autonomous vehicles in countries such as Turkey, which provide their electricity needs from non renewable energy sources, harms the environment. In the countries that provide their energy sources mostly from non-renewable sources, the scenario with the least CO2 emissions in the CAL-LCS and CAL-VSL scenarios was achieved in conditions with 40% connected autonomous vehicle traffic. Finally, a relationship of up to 80% was found between CO2 and speeds two by using KNN and Decision Tree Regressor models.
Evaluating factors affecting construction technology start-up investments and investor behavior
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Yücel, Büşra.; Çomu, Semra.
The construction industry has been unsuccessful in adopting innovative technologies compared to other industries. Construction Technology (Contech) start-ups play a vital role in the digital transformation of the sector by providing unique solutions for particular problems. Nevertheless, start-ups are small companies, and they need to be supported by investors to survive and produce their products or services. In this respect, understanding investor behavior is critical for entrepreneurs to get investments. Accordingly, this study aims to evaluate the Contech start-up environment and factors affecting Contech investors' motivation and investment level. A conceptual framework was developed through an extensive literature review and interviews with professionals. An online questionnaire was held to test the relations of factors with investment motivation and investment share. The data was collected from Contech start-up investors in several countries and analyzed by utilizing Structural Equation Modeling (SEM). The results revealed that i) investor familiarity and entrepreneur characteristics have a positive, and environmental factors have a negative influence on investor characteristics; ii) while investor characteristics have a direct and positive influence, market and product characteristics have a direct and negative impact on investment motivation; iii) investment characteristics have a direct and negative influence, and market and product characteristics have a direct and positive influence on Contech share in investor portfolio. This study contributes to the literature by investigating Contech start- ups and proposing a basis for future research. Entrepreneurs and investors in the Contech ecosystem might benefit from the results in their decision-making process.
Investigating the characteristics of a digitally agile organizational structure for construction companies
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Nasiri, Aran.; Çomu, Semra.
As the architecture, engineering, and construction (AEC) industry embraces digital transformation, the need for digitally agile construction organizations (DACOs) becomes more tangible. According to the literature, the structure of a company’s organization may have an impact on its digital agility. However, no studies have been conducted to investigate the relationship between construction firms’ organizational structures and their business models’ digital agility. This study seeks to fill this gap by conducting exploratory sequential mixed-method research, beginning with the collection of qualitative data from the literature and continuing with in-depth semi-structured interviews with experts. Following that, directed content analysis is conducted on the qualitative data to identify recurring themes in the context of construction companies’ digital transformation, provide a hypothetical definition for digitally agile organizational structure, create a hypothetical model based on defined latent variables, and define measurement factors. Then, a questionnaire is created to put the hypotheses to the test. Partial least squares structural equation modeling (PLS-SEM) is used for this test. According to the findings, a digitally agile organizational structure is less formalized, complex, and highly integrated, and it fosters the digital agility of a construction company’s business model while also providing a fertile environment for agile leadership. Furthermore, construction companies must develop a digital organizational culture through educational programs in order to reduce employee resistance to digital transformation and communicate the change to them. This study adds to the body of knowledge in the field of organizational studies in the contexts of construction management and digital transformation by providing insights into DACOs and paving the way for future research on the subject.
Evaluation of an existing industrial building retrofitted with fluid viscous and viscoelastic dampers under no-pulse and pulse-like base excitations
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Uçkaç, Muhammet Arif.; Soyöz, Serdar.
A retrofitting methodology using passive control devices, was adopted in this study for the performance improvement of an existing industrial building in Malatya, Yeşilyurt. The efficiency of the methodology was investigated through the analytical model developed in SAP2000. The structure was constructed in 1989, and the design report of the structure is unreachable. Therefore, site investigations were carried out to determine the necessary dimensions and material properties as well as soil class. The structure was exposed to severe earthquakes and fire, and hence the industrial building is currently out of use because of possessing risk of life safety. Previous retrofitting studies using steel jacketing and addition of shear walls were not enough to reach the desired level of performance. For this reason, a retrofitting methodology using passive control devices, fluid viscous dampers and viscoelastic dampers, was chosen as an alternative tool for bringing the structure to the desired performance level. Firstly, within the investigation, the performance level of the structure was determined according to TBDY 2018, and the necessity of a new retrofitting methodology was demonstrated. Then, the structure's finite element model (FEM) was updated by adding the passive control devices properly. The Nonlinear Time History Analysis (NLTHA) method was used to obtain the plastic deformation demands on the members. The structure is very close to the East Anatolian Fault, and therefore near-fault effect having velocity pulse characteristics on the response was also considered in the analyses. In line with this purpose, ten different earthquake records, comprised of five no pulse like records and five pulse-like records, were selected according to TBDY 2018, and NLTHA were conducted for the bare frame, damped with FVD frame, and damped with VE frame separately, and results were evaluated.
Simulating the electricity consumption of occupants in dormitory buildings by using agent based modeling
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Moeini, Rasa.; Çomu, Semra.
Buildings are recognized for their significant role in electricity consumption and carbon emissions. Policymakers and researchers have addressed the necessity of realizing the underlying reasons behind buildings' colossal energy consumption. In this regard, many energy-efficiency strategies have been developed to achieve sustainability and lower energy consumption rates. Building energy performance is also proved to be significantly affected by occupant presence and behavior. However, understanding the dynamic relationship between occupants and buildings is not easy due to the complexities of human behavior. Until a few years ago, many building energy performance tools did not even consider occupant behavior in their analyses, resulting in noticeable gaps between actual and predicted energy performance. Strategies involving behavioral changes are considered low-cost and effective methods in reducing building energy consumption. Although researchers have investigated occupants' role in different building types, the number of studies focused on dormitory buildings is limited. Occupant-building interactions in dormitories are more complicated than office buildings because of the differences in students' lifestyles and daily behaviors. In order to examine the role of students in the energy consumption of dormitories, an agent-based simulation was developed and validated using real-time consumption data collected from a dormitory building located on the Kilyos Campus of Boğaziçi University. Results show satisfying accuracy, and this study explains how the model can be used for energy consumption prediction. Some scenarios are also simulated with the model to demonstrate its capabilities for recommending effective occupant-centric energy-saving strategies. The model is adjustable and can be modified to be employed in other similar buildings. Moreover, this study paves the way for other researchers to use the agent-based simulation for occupancy prediction and building energy analysis and gives recommendations on improving and achieving a more sophisticated model.
Morphodynamics of gravel beaches and their response to nourishment
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Farazande, Sofi.; Otay, Emre.
Modeling the long term beach morphology after nourishment provides a better understanding of the nature of the beach. In this thesis, the morphodynamics of a gravel beach at Kalemyel Bay after two nourishments in March 2020 and March 2021 are modeled. The model of each year focuses on four cross-sections and their profile evolution in one year after the nourishment. SWAN software is used to model the wave climate which has the most important factor for the profile evolution. 8 wave conditions that have the highest impact on the profile evolutions have been selected and used in the morphology model. The morphologic changes due to cross-shore sediment transport are simulated in XBeach-G. Longshore sediment transport is modeled with the diffusion equation. The results obtained from the longshore model are superposed on the XBeach-G outputs of the cross-sections. The results of the XBeach-G of the profiles after the nourishment in March 2020 remain less evolved compared to the site measurements. This may imply that an unconsidered storm occurred in Summer 2020 at Kalemyel Bay. The results of the XBeach-G for the nourishment in March 2021 are in line with the long-term estimations of the Bo˘gazi¸ci University Coastal Engineering Laboratory. However, for simulations of both years, longshore transport is overestimated especially on the west side of the beach. The irregular beach fill along the shore affects the longshore transport results. Still, there is a dominance of the cross-shore transport over the longshore transport. The average beach width loss due to cross-shore transport after second nourishment, where the average width gain was 5.90 m, is 3.65 m, while for longshore transport this amount is 1.64 m. It is deduced that the nourishment can be designed such that the fill is thicker in the middle of the beach than the sides since the material will move to the ends of the domain in time.
The effects of post fire re-curing on mechanical properties and recovery of fiber reinforced concrete
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Noori, Mohamed Adil Noori.; Zihnioğlu, Nilüfer Özyurt.; Akca, Abdullah Huzeyfe.
High temperatures or fire may cause significant damage in concrete. Moreover, further deterioration continues at the post heating stage. Although, there are few studies on the post fire rehabilitation of concrete in the literature, most of them focused only on the re-strengthening of concrete. On the other hand, the post fire activities in concrete have a significant impact on both mechanical and microstructural properties of concrete. Therefore, in this study new solution based re-curing techniques were utilized on the concrete specimens at the post heating stage. 7 days of post fire re-curing was applied in order to be more effective, practical and cost effective compared to the longer re-curing periods. At every stage of heating, cooling and re-curing; destructive and non-destructive tests were performed on cubic and prismatic specimens in order to determine the residual mechanical properties and to monitor the extent of recovery. Some of these specimens were also subjected to TGA analyses to better understand the microstructural changes of concrete following heating and the effect of re-curing methods. The results showed further deterioration in air re-cured concrete but recovery in water and solution based re-cured concrete.
The influence of concrete strength on the economy of reinforced concrete columns
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1998., 1998.) Abubakar, Aminu Issaka.; Yerlici, Vedat A.
The effect of increase in strength of concrete on the economy and performance of reinforced concrete columns is investigated. Two different concrete strengths namely 25 and 45 MPa were used to design columns of 16 different buildings with variation in floor panel size and number of stories carried by the column. The study indicates that, improvement on the strength of concrete causes a substantial decrease in the size and / or the reinforcement of columns which in turn lowers the cost of reinforced concrete frames. The decrease in cost ( savings ) is observed to increase with increase in number of stories carried . The cost benefit in reinforced concrete columns from increasing concrete strength decreases as the floor panels get larger.
Quality management in the Turkish construction industry
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1998., 1998.) Şanlılar, Teymur.; Aşkar Altay, Gülay.; Ulusoy, Gündüz.
A detailed survey is conducted with Turkish construction firms to gather information about construction industry and quality management procedures. The questions in the questionnaire are prepared to have complete information about companies' current status and future plans on quality management. The survey is applied to consultant, designer, contractor, and subcontractor firms, since these groups cover almost all-different sub sectors of the construction industry. Twenty-two of the targeted companies answered the questionnaire. The results indicate that almost all of the companies are aware of the relevance and importance of quality management and interested in quality improvement, whereas they are not experienced enough to implement quality management properly and they have problems in documentation, communication, training, and process improvement. The companies can apply ISO 9000 quality assurance system in order to have good start for quality management implementation because it provides a good foundation for quality management.
A comparison of deep shaft sinking techniques; |a case study using the conventional method
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Sciences and Engineering, 1998., 1998.) Özdemir, Murat.; Özturan, Turan.
Shaft is defined as an undeground cavity of an inclination 45 to 90 degrees to the horizontal line, of a straight course, of a minimum cross section of approximately 10m2, and of an essentially larger length in the vertical than in the horizontal direction. There are many applications of shaft sinking in underground constructions but it has to be recognized that worldwide 90 per cent and more of all shafts are sunk for mining purposes.Most of the shafts required worldwide are constructed by conventional shaft sinking which is understood as breaking rock by blasting, loading and hoisting of the broken rock and installation of the lining. Alternative sinking methods to the conventional method are shaft drilling and boring where in shaft boring muck is removed to a lower level and there should be an existing underground connection, and in shaft drilling with muck removal to the surface or to the next higher level. In this study, all these three sinking methods are examined and compared with each other. Conventional sinking method is examined in detail and a shaft, sunk in Çayeli Rize by a conventional method is taken as a case study. Construction steps are explained and sinking equipment alternatives and progress of the method is discussed.
Logistics in computer integrated construction framework
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Sciences and Engineering, 1997., 1997.) Akbaş, Ragıp.; Aşkar Altay, Gülay.; Barbarosoğlu, Gülay.
Infonnation technology implementation in construction witnessed maj or progress in recent years. Hardware and software technology improvements allowed computer use in most of the companies. However there is still much to go to achieve effective and integrated infonnation systems and gain real benefits. Similarly logistics concept, evolved from manufacturing materials management and distribution gains much more importance because of globalization of the world, reduced time to market and customer driven approach. Effective integration of these vital concepts will undoubtedly reveal highly efficient construction. This study particularly investigates construction logistics from infonnation technology point of view considering the current and future trends. Following the recent literature survey to present computer integrated construction idea, an integrated logistics concept in construction is explained. Then a reference data model of construction logistics for construction enterprises is proposed. This model is partially implemented using a relational database management system and object oriented development environment. A case study in a process plant construction is developed to demonstrate the concepts developed throughout the study.
Modeling the shear strength improvement at the interface of lime-stabilized soil and concrete
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Sciences and Engineering, 1997., 1997.) Batukan, Burak.; Baykal, Gökhan.
Drilling operations remold the shaft soil, leading to significant shear strength losses. Lime stabilization has been proposed to increase the shaft resistance capacity of friction piles installed into clayey soils. For verifying this hypothesis lime slurries can be prepared in boreholes prior to subsequent concreting. The infiltration of lime is provided by this means through the cracks and fissures that are exposed during the augering process. The benefical effects of the enabled lime-clay interaction are likely to enhance the shear resistance of the remolded interface zone. Provided that the soil characteristics of the interface have been improved, the required load bearing capacity of piles can thus be obtained without increasing its dimensions. Besides its ease and convenience, the economical aspect of this method makes this proposal even more attractive for field applications. Using the finite element method, the numerical simulations have been performed in order to distinguish the effect of lime as well as the contribution of treatment duration. A simplified finite element model has been developed under the ANSYS 5.2 computer software in order to analyze the response behavior of lime treated and untreated natural soil with concrete under identical shearing conditions. The models have been primarily founded on the mechanical parameters (Young modulus, Poisson ratio and yield stresses) of the interface soil and its surrounding semi-finite soil domain. Supporting the corresponding laboratory test results obtained formerly by Metehan C. T. (1994), figures have revealed an approximately doubled shear strength at the interface consequent to lime treatment. However, the varied interface thickness accounting for the intensity of lime infiltration, which is in turn dependent upon the duration of treatment, revealed no significant impact onto the results obtained.|Keywords: Cast-in-situ concrete piles, skin friction, lime stabilization, diffusionadvection, finite element modeling, interface, thin-layer element.

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