Department of Civil Engineering
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Item NUMERICAL MODELING OF THE AUGUSTUS TEMPLE(2010-01-27) DÖĞER, Rıdvan; SARI, Yasin DursunThis thesis reviews the numerical modeling of the Augustus Temple. “3DEC” software by Itasca and “PLAXIS” software by PLAXIS B.V. were used to perform the numerical analysis. Recommendations for future testing and monitoring were discussed. Analysis methods and properties of dry stone structures were also discussed in this thesis.Item ANALYTICAL INVESTIGATION OF MULTI-LAYER COMPOSITE TUBES SUBJECT TO PRESSURE(2010-01-27) ATLI, Ahmet; AKIŞ, TolgaThe aim of this study is to present an analytical approach for the stress analysis of multi-layer composite tubes under internal and external pressure. The expressions of stresses and displacements for single, two and three-layer tubes are obtained and the critical cases of yielding are examined using Tresca’s and von Mises yield criterion. The analytical solutions are checked numerically for different material sets and the stress and displacement distributions are obtained. It is found that yielding begins at the inner surface of the single layer tubes under internal or external pressure. For the two-layer tubes, yielding may begin at the inner surface of the inner or outer tubes or simultaneously at both locations. For the three layer tubes different cases of yielding may occur depending on the material properties. In the study, the conditions for these various yielding cases are thoroughly examined.Item INVESTIGATING USE OF UNTENSIONED PRESTRESSING STRANDS IN REINFORCED CONCRETE FLEXURAL MEMBERS(2011-01-26) ARSAVA, Tuğba; BARAN, ErayIn this thesis use of untensioned prestressing strand in flexural members as tension reinforcement is investigated. In manufacturing of prestressed/precast concrete elements prestressing strands are used. According to a questionnaire survey carried out by companies being active in manufacturing of prestressed/precast products it is observed that the remaining pieces of cut strands are used only as lifting hooks. In case these remaining pieces could be used as bending reinforcements, it will be possible to make a more economical use of these high strength products which are imported from abroad. When conventional reinforcing bar and high strength strand compared, high strength strand strands indicate different stress-strain behavior. The fulfillment of the design requirements of the contemporary building regulations about using concrete elements reinforced with high strength strands instead of concrete elements reinforced with conventional reinforcing bars, is still a field which is open to investigation and research. Aiming to contribute closing the gap in literature on the subject issue, a research is carried out consisting of laboratory tests supported by analytical analysis. thirteen reinforced concrete beams prepared, seven out of thirteen beams were reinforced with conventional reinforcing bars and the remaining six beams reinforced with high strength strands. All beams were tested under two point loading. Following the laboratory tests, a numerical parametrical evaluation is carried out on beams with different cross-sectional areas and with different material properties. Following the laboratory tests and the numerical analysis, the behaviour of concrete members which are reinforced with high strength steel strands instead of standard reinforcing bars under bending conditions are evaluated and the differences observed are noted. Finally the applicability of the procedures with regard to provision of moment carrying capacities and the minimum required ductility levels identified in American Concrete Institute (ACI-318) and TS500 regulations to concrete beam elements reinforced with high strength tensile strands are reviewed and summarized.Item LATERAL LOAD BEHAVIOR OF COLD-FORMED STEEL WALL PANELS(2013-06-15) ALICA, Hüseyin Çağatay; BARAN, ErayIn this thesis, lateral load behavior of cold-formed steel (CFS) wall panels was investigated. For this purpose full-scale CFS wall panel specimens were tested experimentally. Measured load capacity of wall panels were also compared with numerically predicted values. Experimental part of the study included monotonic lateral load testing of twenty one CFS wall panels. Wall panels were sheathed with oriented strand board (OSB), fibercement and betopan panels. Influence of additional parameters, such as sheathing panel thickness, screw spacing, CFS section size, existence of diagonal struts and double-sided sheathing was also investigated. Using the information obtained from load tests, the lateral behavior of the wall panels was studied and the differences and similarities in the response of these panels were investigated. Response of wall panels under lateral loading was determined to be directly related with the behavior of the hold-down attachment used at the base of panels. In most of the specimens tested in this study, the strength and stiffness of the hold-down attachment prevented the wall panels to reach the expected strength and stiffness levels. Among the parameters investigated in this study the one that had the most significant effect on the behavior of wall panels was the screw spacing used at exterior framing members. Between the cases of 15 cm and 30 cm screw spacing, the increase in load capacity of wall panels was between 37% and 85% depending on the type and thickness of sheathing panel.Item DEVELOPMENT OF STEEL-CONCRETE HYBRID CONNECTIONS FOR PRECAST CONCRETE MOMENT-RESISTING FRAMES(2013-06-21) KURTOĞLU, Metin; BARAN, Eray; BARAN, MehmetHybrid beam-column connection details to be used in precast concrete moment resisting frames were developed in this study. Experimental part of the study included testing of fourteen precast concrete beam-column connection specimens utilizing the proposed hybrid connections and two monolithic beam-column connection specimens under reversed cyclic loading. Strength, stiffness, energy dissipation capacity and ductility characteristics of the specimens were examined by evaluating the test results. The effect of various parameters including the geometry of steel connection components, amount of bolt pretension to be used at the connection region, method of anchoring the connection components in beam elements, and the detailing of beam reinforcement near the connection region on the behavior of the beam-column connection region was investigated. After producing useful experimental evidence, further analytical studies were conducted in an attempt to study the behavior of typical precast concrete structural systems made of moment resisting frames under lateral load effects. Within this context, finite element models of three- and five-story planar frames were prepared and lateral nonlinear static pushover analyses were conducted on these models. The experimental and analytical studies revealed that the proposed hybrid precast concrete beam-column connection details offer the potential of providing a performance comparable to their monolithic counterparts.Item ENHANCING CIVIL ENGINEERING EDUCATION USING ACTIVE LEARNING TECHNIQUES(2013-08-14) ÇALIŞKAN, Nihan Tuğba; MERTOL, Halit CenanIn the last few decades the civil engineering prefession has rapidly developed to be able to adapt to changing conditions in various areas worldwide. Besides, the 21st century students are also completely different from the students who lived in the 20th century. The advances in technology have a great influence on these students. They don’t know the life before computer, cell phones etc. The traditional educational methods containing passive teaching methods no longer work for current students. Most of the students in this century are active learners and active teaching methods should be used to be able to get good performance from these students. In this study computer games, hands-on-practices, experiments, laboratory works used as active teaching methods and applied on different courses such as Statics, Dynamics, Strength of Materials, and Fundamentals of Reinforced Concrete, and the change in students’ performance is evaluated.Item ROAD SAFETY AUDIT AND A CASE STUDY ON KANO-KADUNA ROAD IN NIGERIA(2014-06-09) BALA, Nura; AYDIN, CumhurThe consequence of increasing number of traffic volume, road safety improvement is becoming a major policy for the road authorities. Road accidents create both social and economic cost on the country’s economy. When this is taken into consideration, it is therefore important to display different solution alternatives considering the budget limitations of the road authorities. Road accidents are serious problems throughout the world especially in low and middle income countries considering social, health and economic terms. The number of road accidents in such countries tends to increase every year. In this thesis, a case study is selected in Nigeria and the studies were performed to summarize actual practices of road safety auditing on existing roads in different countries. By taking account these different opinions and auditing procedures into account a strategy for road safety auditing on existing roads that fits to Nigerian roads conditions is proposed. For an evaluation, a case study was conducted in order to determine whether the proposed methodology adds a value to the highway network follow up and improvements. Based on this study, the audit report was prepared to summarize findings with possible countermeasures.Item WORK ZONE SAFETY AUDIT AND CASE STUDY IN KANO, NIGERIA(2014-06-09) UMAR, İbrahim Khalil; AYDIN, CumhurThe continuing increase in vehicles demand resulted in the construction of new roads as well as improvement of the existing ones, hence creating more work zones. These work zones poses more dangers to the life and safety of road users and the workers performing various tasks. This thesis research reviews the concept of work zone safety audit at construction stage. The various safety measures for efficiently and safely guiding traffic through the work zone, improving the safety of workers, equipment, and the road users traversing through the work zone were also reviewed. A case study on a Nigerian highway was conducted where lack of regular maintenance of the installed temporary traffic control devices, non-compliance with standards, human behaviors like over speeding, disregard to traffic rules in the work zone were identified to be the major causes of all hazards within the work zone.Item SAFETY AUDITING ON URBAN ROADS WITH SPECIAL EMPHASIS TO INTERSECTIONS IN A CASE STUDY IN KANO, NIGERIA(2014-06-09) HABIBU, Abubakar Sani; AYDIN, CumhurThe current international reviews and action plan strategies regarding rapid increase in road traffic volumes and present status of huge number of traffic accidents have made road safety audits/inspection procedures necessary major policy for implementation in any country worldwide. Road traffic accidents affect social and economic aspects of any country which need serious and urgent action to be taken in order to provide effective improvements, solutions, suitable and desired counter measures so as to avert the present situations. In this aspect, urban road safety audits have been analyzed in the study. A case study of an urban Katsina Road section in Kano, Nigeria was selected and evaluated using actual practices, strategies, and procedures of road safety audits in developed countries in relation to deficiencies, hazards and intersection capacity and level of service measures. Based on the evaluated case study conditions through proposed methodology, different number of safety defects were detected and related counter measures were proposed for the present case study accident potentials, capacity and level of service for accident severity reduction and elimination.Item IN-DEPTH ACCIDENT ANALYSIS AND CASE STUDY IN NIGERIAN ROAD AND TRAFFIC CONDITION(2014-06-09) DAYYABU, Abubakar; AYDIN, CumhurThe in-depth accident investigation is the process of detail data gathering related to the involved persons, the road/environment, involved vehicles for the purpose of detail analysis and the reconstruction of the accident. It can be used to conclude on the main causes of accidents and proposing an appropriate and effective countermeasure, to prevent re-occurrence of similar accident type. The thesis has reviewed and modified European Truck Accident Causation Study methodology. The modified methodology was applied on Nigerian Highways. In the modified methodology 100 parameters comprising of detail information of involved persons, vehicles, road and environment were collected and analyzed to come up with the accident causes and proposed an effective countermeasure. The use of the Nigerian National Accident Investigation Manual, the comprehensive Truck database can help in better understanding the main causes of truck involved accidents, and hence providing effective countermeasures.Item FLEXURAL BEHAVIOR OF PRECAST PRESTRESSED CONCRETE HOLLOW-CORE SLABS WITH CAST-IN-PLACE CONCRETE TOPPING(2014-06-09) HARUNA, Sadi İbrahim; BARAN, ErayFlexural behavior of precast prestressed concrete hollow-core units with cast-in-place concrete topping was evaluated through load testing of five full-scale specimens. The specimens were divided into two groups of wide and narrow. A cast-in-place concrete was cast on top of the hollow-core units selected from the two groups to form a composite system. An additional specimen was tested with restraining mechanisms used at both ends in order to reduce the relative slip between the hollow-core unit and topping slab. Presence of cast-in-place topping slab improved the behavior of hollow-core units by increasing the flexural crack initiation and maximum load capacities as well as the stiffness. Specimens tested with cast-in-place concrete topping slab suffered from a sudden drop in the load resisting capacity due to the slip of the topping slab relative to the hollow core unit. As a result of premature loss of composite behavior, the predicted load capacity of these specimens assuming a fully composite behavior remained on the non-conservative side. The loss of composite behavior corresponded to an interfacial shear strength value that is smaller than the values specified by the ACI and AASHTO Specifications. The results obtained in this study suggest that floor system made of cast-in place concrete topping placed over the machine finished surface of precast concrete hollow-core units with no interfacial roughening is not able to provide the interface shear strength required to develop a fully composite behavior.Item PARAMETRIC STUDY OF OIL AND GAS INTERNAL PRESSURES IN BURIED PIPELINES(2014-07-09) SHAALAN, Heyam Hussein; SARI, Yasin DursunThis study presents a parametric analysis of the behavior of buried oil and gas pipelines in different soil condition, subjected to static loading, where the influence of fluid internal pressures is taken into account. The crown steel pipe displacement has been computed numerically with respect to the applied surface loads for different burial depths of soil conditions (dense sand, loose sand and clay). The mechanical behavior of pipes is evaluated by means of a two- dimensional finite element method PLAXIS. A large number of the calculation results were analyzed and evaluated. On this basis, the results were fitted by non-linear regression analysis. This study is concerned with the effect of soil media (dense sand, loose sand and clay), burying depth, fluid materials (oil and gas), location of applied load, adjoin pipes, internal fluid pressure and mechanical parameters of pipe (such as pipe diameter and pipe wall thickness).Comparison was also carried out.Item DYNAMIC AND STATIC ANALYSES OF THE OIL AND GAS PIPELINES(2014-07-09) HASSAN, Marwan Adil; SARI, Yasin DursunIn this study, a numerical calculation on interaction between soil and steel pipelines was performed. Properties of soil and pipe may cause significant effects on the movements of buried pipelines. To improve the understanding of the behavior of buried pipelines subjected to dynamic and static loading, different oil and gas pipes have been considered in this study. Earthquake load of magnitude 5.4 with time shaking of 10 sec and surface loads (50, 100, 150 and 200 kPa) have been used. To simulate numerically this effects, 2D finite element method PLAXIS is performed. The results are discussed and fitted by univariate linear and non-linear analysis. Some influential factors such as soil types (clay, loose and dense sand), soil layers (one, two and three soil layers), underground water table, static water loads (of height 20m above soil), burying depth, pipe diameter and pipe thickness are discussed in details. Based on the results, it can be concluded that these factors are important items on pipeline displacement for both static and dynamic loads. Some significant comparisons and conclusions are drawn.Item FLEXURAL BEHAVIOR OF LIGHTLY AND HEAVILY REINFORCED STEEL FIBER CONCRETE BEAMS(2014-09-07) BELLO, Hussain Jibril; MERTOL, Halit Cenan; BARAN, ErayFlexural behavior of lightly and heavily reinforced steel fiber concrete beams was investigated in this research. Test series consisted of 20 singly reinforced beams (10 pairs of beams) having 180×250×3500 mm dimensions. The main parameters in the testing program were the type of concrete and the amount of longitudinal reinforcement. Ten different longitudinal reinforcement ratios (with a minimum of 0.2 and a maximum of 2.5%) covering the range from under-reinforced to over-reinforced beam behavior were used in the testing program. Two specimens were tested for each longitudinal reinforcement ratio, one specimen using ordinary plain concrete (PC) and another specimen using steel fiber reinforced concrete (SFRC). Load-deflection behaviors were obtained and evaluated in terms of ultimate load, service stiffness, post-peak stiffness, and toughness. The results indicate that the use of SFRC increases the ultimate load and service stiffness of the beams slightly compared to that of PC specimens. As reinforcement ratio increases, the ultimate deflection of SFRC specimens becomes significantly greater than that of PC specimens. For over-reinforced sections the post peak stiffness of the SFRC specimens is observed to be significantly lower than that of PC specimens. The toughness of SFRC specimens is greater than that of PC specimens with the difference being significantly larger for over-reinforced sections. Experimentally determined load-deflection relationships were compared to the load-deflection curves obtained from sectional analyses based on strain compatibility and best fit stress-strain relationships for SFRC in tension and compression in the literature are presented.Item OVERALL COST OPTIMIZATION OF A CONCRETE BRIDGE USING SIMULATED ANNEALING ALGORITHM(2014-10-07) TAFIDA, Abba Kabir; AKIŞ, Tolga; DENGİZ, OrhanCost of construction is one of the critical success factors for construction project, which have gone up to a level that there is need to reduce its effect in construction projects. Overall construction cost minimization helps to reduce the high cost of construction in concrete bridge constructions. In order to minimize the construction cost, there is need to develop a decision support tool that is capable of selecting appropriate span length, number of spans, girder type, number of girders, pier sizes, number of piers, footing sizes and estimate their total cost including all other bridge elements. The purpose of this study is to determine the overall optimum cost of bridge, optimum span length, optimum number of span and a prototype bridge cost optimization decision support system, which is applicable to bridge construction projects. The proposed overall cost optimization decision support system can analyze different span lengths and different precast I-girder type alternatives in order to realize optimum cost of the bridge construction project. A cost optimization process model has been developed and coded in MATLAB computer program to perform the design and estimate the overall optimum cost of the bridge. The considered bridge superstructure is supported by precast I-girders resting on pier cap and the substructure is constituted by multicolumn piers and rectangular spread footings. Standard AASHTO precast I-girder types are used in this study and the piers and footings are designed by using allowable stress design method. Minimum depth of super structure, I-girder type, maximum span length, spacing and overhang width constraints are considered. A simulated annealing algorithm is used for the optimum design of the bridge and overall construction cost is taken as the optimality criteria.Item BEHAVIOR OF BOLTED TENSION SPLICE CONNECTIONS IN STEEL LATTICE OVERHEAD TRANSMISSION LINE TOWERS(2014-11-06) ŞEN, Gökmen; AKIŞ, Tolga; BARAN, ErayBehavior of bolted splice connections in steel lattice overhead transmission line towers under tensile loads was experimentally studied. Seven specimens with each of them having a different connection detail were tested. The main parameters used in the testing program were the number of bolts used in the connection, presence of connection reinforcement angles, and the number and geometry of filler plates used between the main members. Main aim of the study was to gain a better understanding of the load-flow mechanism in the connection. The specimens were observed to exhibit similar response, which includes an initial linear behavior followed by a yielding portion and a secondary linear portion that continues until net section fracture of the upper main member. The measured load capacities of specimens were compared to the predicted capacity corresponding to the net section fracture of the upper main member. The measured and predicted capacities were observed to agree acceptably well with each other. Based on the experimental results, the redundant members in the connection were identified and recommendations were provided in order to simplify the connection geometry by eliminating the redundant members.Item STUDY ON THE FUNDAMENTAL PERIOD OF VIBRATION FOR BUILDINGS WITH DIFFERENT CONFIGURATIONS(2015-01-27) BASHAR, A. Shon; TUNÇ, GökhanThe determination of the fundamental period of vibration for a building is essential in the earthquake design field. According to the various building codes, there are limitations on this topic. In this study, only reinforced concrete buildings with various floor levels and structural configurations are investigated. As part of this investigation, a total of 105 models representing unique sets of 21 layouts is constructed using a commercially available software package, ETABS. In the seismic analysis phase the response spectrum analyses are conducted according to the Turkish Seismic Code, 2007. Not only the periods, but also the lateral deflections are evaluated in detail by using the code associated limitations outlined in the 1997 and 2007 Turkish Seismic Codes and the ASCE 7-10. The intent of this study is to understand the dynamic behaviors of buildings with different configurations under severe seismic loads. The framing type, and number of floors and in-plane aspect ratios are studied in this thesis. For this purpose, five sets of floor levels, 10, 20, 30, 40, and 50 stories are studied. The results are discussed and their associated effects on the existing period equations in the Turkish and American codes are studied.Item STRENGTHENING AND REPAIR METHODS IN IRAQ FOR REINFORCED CONCRETE BEAMS(2015-01-30) MOHAMMED, Anas Malik; TUNÇ, GökhanShear or flexural failure, or both, may occur on reinforced concrete beams due to blast loading. In this study, the methodology explaining how to repair the damaged structural elements using locally available materials in Iraq is presented with analytical design calculations and finite element methods. Fiber reinforced polymer (FRP) composite materials are commonly used across Iraq for rehabilitation and repair of damaged structural elements. The applications of these available materials along with their strengthening methodologies are investigated specifically for damaged RC beams under explosive loadings. In particular, the attention is given to FRPs since they provide effective solutions for repair and rehabilitation of blast damaged beams. In this study, a total of nine beams with and without FRPs are used to understand the impact of damage and how effective the strengthening methods are based on ACI-318-2011 and ACI-440-2R. These beams are also modeled using ANSYS software. The results from analytical equations and the FE models indicate that the FRP reduces the total deflection while it increases the capacity of beams in shear and flexure. In order to verify the ANSYS results, a simple Visual Basic program was also developed to calculate the actual beam capacity in shear and flexure using the equation in ACI-318-2011, and ACI440-2R-2008. The results from the visual basic program were compared to the results from ANSYS.Item COMPRESSIVE AND TENSILE BEHAVIORS OF STEEL FIBER REINFORCED CONCRETE(2015-06-26) ABDUSSALAM, Alfadhil. A. Gheit. Alfadhil; MERTOL, Halit Cenan; BARAN, EraySteel fiber reinforced concrete (SFRC) is a concrete mixture containing discontinuous, discrete steel fibers that are randomly dispersed and uniformly distributed. The quality and quantity of steel fibers influence the mechanical properties of concrete. It is in general accepted that the addition of steel fibers significantly increases tensile toughness and ductility, also slightly enhances the compressive strength. The benefits of using steel fibers become apparent after concrete cracking because the tensile stress is then redistributed to fibers. The objective of this study is to investigate the compressive and tensile behavior of steel fibers in reinforced concrete by conducting an experimental program consisting of load testing on various specimens made from conventional concrete (CC) and steel fiber reinforced concrete (SFRC). Test series consisted of cylindrical compression (100×200 and 150×300 mm) and prismatic modulus of rupture (150×150×600 mm) specimens. Tensile tests on reinforcing bars surrounded by prismatic concrete specimens were also performed. The variables used in these tests were lengths (500, 1000, and 1500 mm) and cross sectional dimensions (60×60, 100×100,150×150, 200×200 mm) of the prismatic concrete specimens around reinforcing bar. Load-deflection behaviors were obtained and evaluated to develop the compressive and tensile stress-strain relationships of SFRC. Experimental load-deflection relationships obtained from modulus of rupture tests were compared to the predicted load-deflection curves determined using compressive and tensile stress-strain curves obtained in this research. Also the stress-strain relationships available in the literature were used predict the behavior.Item NUMERICAL ANALYSIS OF BOLTED CONNECTIONS IN STEEL LATTICE TRANSMISSION TOWERS(2015-06-27) DRAİSAWİ, Ammar; AKIŞ, Tolga; BARAN, ErayBehavior of a specific type of bolted splice connection used in steel lattice transmission towers under tensile loading was investigated numerically. Finite element models representing the specimens tested in a recent experimental study were used to study the force transfer mechanism at the splice connection of main members. Several connection geometries ranging from a complex geometry with many bolts and reinforcing components to a much simpler geometry with much fewer components were considered, and the effect of connection configuration on the overall response was investigated. A parametric study was also conducted in order to determine the minimum number of bolts that can be used to have a connection response comparable to that of the original connection configuration. Finally, some of the connection configurations were also investigated under compressive loading to get a general idea about the possible response and to identify the differences in behavior under tensile and compressive loading.