Theses supervised by Prof. Dr. Tuncer Çelik
18 theses · Altınbaş University
Simulation and modeling of flexural behavior in concrete beam under different loading shapes
Using of beams in construction is common and very required as these elements can play important role for carrying the external loads as a part of the whole building. The problem of less ability for the concrete materials for handling the tensile stresses considered as obstacle for being freer in the design procedures. For improving the strength, the tensile zone in the beam is assisted by reinforcement, the cracking in concrete as well can still occurs due to reaching the limit of resistance so that understanding the maximum loading that can lead to this case is important key in the design steps. Four external forces were adopted in this study. The cases were single force, two concentrated force, rectangular shape load, and triangular shape load. These four states of loading were applied on simply supported beam so that flexural analyzing was carried out in the way of understand and calculation the maximum load in each case that can be lead to the initial cracking in the tensile fiber of concrete cross section. After the analysis was made for each case, different relationships were identified by graphs which involved the increasing or decreasing between the final cracking load and the changing of cross section width, cross section height, compressive strength, and also the point of action for the concentrated loading. The behavior of the relationships was derived toward regression correlation using SPSS software in which for predicting governing equation for the cracking moment that can be adopted to identify the maximum allowable load that can be act without cracking of concrete in tensile part. Three zones were assigned as the curve flow out to reduce the difference between the actual cracking moment and the predicting cracking moment for least values. Simulation for the all four cases was implemented using ANSYS workbench program and the results were explained in graphs that contained the behavior of stresses and strain and deformation along the span of the beam under each case study.
Elastik temel üzerinde polipropilen elyaf takviyeli kiriş davranışının incelenmesi
Polypropylene fibre reinforced beam is a new successful material in improving the behaviour of beam concrete - especially when it combines with the conventional Polypropylene reinforcement- there's an absence of codes and standard that predict and estimate the real punching capacity of the panels containing polypropylene fibre especially when it is subject on elastic foundation. Many types of reinforced concrete beams have been analysed and the solution of finite element was supported with the data from lab work. A number of parametric works were created. The influence of various key finite element and material factors, such as mesh distribution, density, and mesh size effects on the accuracy of three-dimensional finite element model outputs, was investigated. The load-deflection curves at the centre of the polypropylene fibre reinforced beam, as well as the yielding reinforcement occurrence, indicated that the behaviour of the modelled specimen may be elucidated by the load-deflection curves at the centre of the comparable traditional concrete beam.
Statistical analysis for the affectivity of reinforcement behavior on the strength of concrete elements
The study aimed to find out how the reinforcement in both longitudinal and vertical directions can contribute to the internal strength of the concrete beam according to the ACI code. The study set and analyzed the equations that included the impact of the steel area in both directions and the other properties of the member and programing them so that the resultant cracked moment, ultimate moment strength, shear strength of steel, and concrete shear strength were identified according to each equations and each limitations in the code. The study made many numbers of charts that included the relationship between each strength item and the steel area. The maximum shear strength of concrete according to the longitudinal reinforcement was identified and modeled into more direct equation so that the designer can identified the maximum contribution of the longitudinal reinforcement on all strength items of the beam. The study made the analysis for the cases of RC beam under double concentrated loads and other case under uniform loading. The impact of load magnitude, the study showed the behavior of the two cases according to the steel area used in number of charts that can enhance the design issues. The charts including the impact of the steel areas on strength of concrete and the maximum shear strength (Vc) obtained for various effective depths and widths of beam values. For supporting the outline of the study, simulation was made for each case of the RC beam under the techniques of ANSYS program. The simulation showed the structures of both the vertical and the longitudinal reinforcement and how the stresses and the strain behaviors along the span length. The simulating also showed the directional deformation of the cases. The variation of the shear force along the section of the beam was showed by diagram that obtained by ANSYS program.
Seismic evaluation of reinforced concrete shear walls
Dynamic loadings necessitate shear walls that are constructed appropriately. It's crucial to hit this mark in order to prevent serious damage to the massive shear wall in the event of an earthquake. When an earthquake occurs, the ground moves in all directions, but it is the vibrations that affect the walls and cause them to distort in ways that are not expected. Consequently, this study offers insight on exploring the dynamic response of three types of shear walls under seismic condition, which is very important in view of the catastrophic effects of shear wall failure. After validation, the study was split into three sections: the first examined stiff shear walls; the second, shear walls with uniform holes; and the third, shear walls with non-uniform holes. The ANSYS application was used to accomplish this mission. The mode analysis and model deformation during testing were observed and reported. Numerical results of the seismic effect, including deformation types and the shape of failure in the shear wall structure, are shown, and the results are corroborated with prior research based on the seismic load response
Simulating and modeling the strengthen behavior of reinforced concrete T- section beam
The structural workability of T-section members are important key solution to increase the capability of the section to handle the compression stresses in which the flange in the section and the web part can play together considerable role in the increasing of the section internal strength. The study started in its analytical routine by structural analysis for the T-section that used to face high magnitude of external loading starting from 50 kN/m. the study set the needed equation that used to identify the internal strength of the member including the geometry of the section. The study then move the analysis into deriving new equations that collected in them the parameters of the structural performance of the member. The linking of the ultimate needed moment in the equation gave important looking to design acceptance and the strength of the member. The derived equation give the residual term (R) in which its magnitude must be more than one for better design conditions. The study made many number of relationships for each parameter in the T-section (including depth of flange, width of flange, effective depth of member, reinforcement, and width of web). The study processed the relationships by applying curve fitting techniques into the dots of a specific figure to reach the applicable equation that used to give the magnitude of the residual in which the design concepts been satisfied the needed purpose. Collection of the curve fitting equation toward building more simple form of equation that included the main parameters was made to improve the T-Section design concepts. The equation can be used to investigate the minimum magnitude for each parameter to be assigned in the design. The simulation of the T-section cases was made using ANSYS program. The simulation results was made for tow dimensional cases and the results were showed in 3d images.
Statistical analysis and modeling for the structural performance of continues beam system
The continuous beam system is important form that appeared in various types of construction projects like ordinary and tall buildings. The analysis of the moments in the system spans cannot reached easily as the system have many unknown according to simple equilibrium analysis. The study aimed to build effective analysis for the continues beam system starting from the analysis of the moments at joints based on slope deflection method. The study the link the analytical pathway with structural analysis by using ultimate design method. The study made many linearization process on the form of drawing to extract the best fitting of each parameter with magnitudes of the main moments at joints. The study converted the equation into one equation for each moment at the external and internal joints based on the uniform loading at each span and the spa length that designed for the system. The study analyzed the effect of the structural parameters on the safety factor including the effective depth and the width of the members. The study built new equations that link the magnitude of the applicable safety of factor and the magnitude of the uniform loading. The two stages of the study was made to improve the design of the system as the designers can identify the magnitude of the moments and also the required geometry and strength of the members to be considered. The study made simulation of the cases using ANSYS program by building the geometry of the system under various uniform loadings. The study showed the bending moments, the shear forces, and directional deformation for each case of loading. The study showed all items in related figures, tables and images to explain the outline toward the results.
Rijitlik matrisi yöntemine dayalı kirişler için yapısal analizin geliştirilmesi
The using of beams in the form of steel or concrete materials is widely adopted in the construction projects. The conditions that coming with the design of the beams and the internal forces and moments depend on the cases of loading, the geometrical and physical properties of the beams, and the supporting states. The stiffness matrix is a general tool that take into account these parameters for evaluating the shear force and the bending moment diagram along the spans of the beams in part or all the construction body. The stiffness matrix can become more bigger when increasing the number of beam spans or that influence the overall internal stresses inside the member. In the present study, a technique based on Gaussian elimination theory was applied on the body of the stiffness matrix toward finding the required variables in less steps with same degree of accuracy. The study converted the matrix that used for two spans beam from six rows and six columns to only two rows and two columns that the magnitudes of the slope of deformation can be determined then the reactions and moments can be identified easily. The study move to more analytical steps by analyzing the relationship between the uniform loading, the length of span, and the beam stiffness condition EI with each of the four parts of the derived matrix: A1, A2, B1, and B2. The resultant of that analysis was building of new simple equations that can be used to obtained the four main parts of the matrix without the previous steps of the conventional stiffness matrix and the Gaussian elimination steps. The results of the new equations were checked by evaluation the values of the main parts according to the original steps and the derived equation. The differences were so small indicating the feasibility of the derived method to contribute in positive role for the design purpose. The study explained the variation of the shear forces and the bending moments along the beam spans by building simulation of specific case of beams under uniform loading by using of ANSYS workbench program. A full mathematical model for calculate the displacements and reactions has been made in MATLAB/Simulink from the main four parts of the stiffness matrix. In aim of making this model being used in analysis of continuous beam easily. Besides make use of it in field of understanding the analysis method.
Belirsiz betonarme kirişlerin eğme analizinin iyileştirilmesi ve modellenmesi
The modeling of the indeterminate beams analysis under concentrated and uniform loading was the aim of the study. The study defined the geometrical and loading conditions for each case then built its analysis pathway by using the method of slope deflection. The analysis steps including the fixed end moments and the other parameters like the length of beam spans and the magnitude of loading and the cases of joint. the study links all these parameters into equation then derived effective equations based on the relationships and the degree of impact between each parameter and the moment at the second joint which used to be the initial identifies internal moment that ca ease the reach to the other internal moment and the shear forces as well as the joint reactions. The study made number of correlation and checking stages during the scientific path to make the resultant equation be more effective and applicable. The equation obtained considered for two main cases: the first case was the beam with three spans under concentrated load in which load for each span. The second equation was for the case that three spans indeterminate beam under uniform loading. The value of moment reached were examined for both the calculated and the derived state. The difference was so small indicating the closing of the deriving model to the original steps of calculation. The simulation for the cases was done by using ANSYS program which the geometrical shape and loading condition were drawn then analysed under the finite element technique. the magnitude of the moment reached by ANSYS was so satisfied that derived in which the simulation shows visual images for the internal force variation along the spans including the state of directional deformation, the bending moments, and the shear forces. The shear force and bending moment diagram were explained also by ANSYS program.
Shear strength of concrete beam using alternative steel reinforcement
The design shear strength must be sufficient to prevent a shear failure which is characterized by small defects that are difficult to observe as well as a lack of ductility where it suddenly occurs without warning other than flexure failure. Many researchers investigated the structural behavior of concrete beams under the shear effect experimentally, and they focus on the improvement of concrete properties by enhancing the concrete compressive strength of added steel fibers, some of these work's study using new types of reinforcement instead of ordinary steel stirrup. Experiments on concrete beams subjected to a concentrated point load at mid-span for different parameters of concrete compressive strength (30, and 50 MPa), shear reinforcement types (steel tube, and steel stirrup), and arrangement of shear reinforcement (angle of reinforcement 45º, and 90º). Ten specimens were tested to study the behavior of concrete beams under the shear effect. The dimensions of the beam are 160*300* 1150 mm for width, height, and length respectively. The clear span of the test specimen is 1000 mm. the longitudinal reinforcements are 3 Φ 16 mm in the bottom layer and 2 Φ 8 mm in the top layer. Also, the material properties (concrete and steel) are measured in this work. The steel tubes used instead of the steel reinforcement bar were filled with concrete materials, except for two specimens in which hollow tubes were used. The results of experimental work show that the tested specimens produced cracks resulting from bending and shearing stress, but the shear cracks appear before flexure cracks. The minimum cracking load that appears in the specimen has 29.35 MPa as concrete compressive strength, while the maximum cracking load that appears in the specimen has 48.77 MPa as concrete compressive strength. The tested specimens have failed under the influence of shear stresses, and the type of failure can be classified as a brittle failure (shear failure modes). As a result of the increase in the compressive strength of concrete, the ultimate load is higher for the tested specimens. specimens containing 45° shearing steel reinforcement had higher resistance than specimens containing 90° shearing steel reinforcement. Finally, the alternative shear reinforcement (steel tube) used instead of ordinary steel stirrup is considered acceptable to resist shear stresses.
Statistical analysis for the structural behaviour of two-way reinforced concrete slab
The coefficients distribution method for the slab distribution of moments was analysis by the study. The analysis was built by taking the case of slab with beam between all supports. The study took two lines in the study: the first was the explanation of the ACI code tables related to the method of distribution coefficients. The second line was bonding the effective parameters into simpler equations to find out the destination factors for the moments in the interior panels in which negative and positive case. The study showed the simplifying output by examining the effect of the beams height and widths, and also the slab lengths of the panels in each direction. The study derived the magnitude of αm as it the average of the impact of the moment of inertias for beam and slab at each side of the panel strip. The study then mixed the statistical processes in the analysis techniques by evaluation the effect of the beam width and height on the distribution coefficient and the variation happened by identifying the standard deviation for each value when beam width and height been equal. The study explained this state by drawings that showed two stages of variation for the case of interior negative moment coefficients while one stage of variation for the interior positive moment coefficients. The study showed the way to enhance the identifying of the interior moment coefficients by linking the equation that derived for the ACI table for negative and for positive interior moment and the equation that derived for αm. The study supported the behavior theory of the moments action on the slab panels by simulating the cases by ANSYS program. the normal stresses at each direction showed the considerable attacking of the moments portion on the interior panels.
Evaluating the effects of cost overrun in construction projects
Overrun project cost is the main challenge in the construction industry It represents one of the important obstacles to economic development. this industry in Iraq faced the problem of overrun costs. for that, the present study investigates the various factors in causing cost overruns throughout the construction projects. The factors selected in this research were 35 factors. three processes have been used in the research methodology, the first is the Delphi method which is used to create the dataset for the investigation process. the second method is used the correlation coefficient which measures the strength between the factors. finally, the third is the AHP method which specifies the main effective factors of the overrun cost condition. the results observe seven effective parameters, they are Quality of Plans & Specifications, Size and Type of Construction Project, Skill level, Wrong estimation of time and budget, monitoring the time schedule, change orders, Materials and manufacturers' products are clearly defined. the evaluation process of these factors provides the most effective factor in AHP results is monitoring the time schedule which can overrun 16% of the project cost. According to the expert's opinion, it is significant results.
Geometric design and analysis of space framed structures for load transmission in joint - to check the stability and the safety of joint
A space frames or space structure is a stiff, lightweight, truss-like structure that is created from interlocking struts in a design in architecture. To span enormous expanses with minimal interior support, space frames could be employed. For both long and short span constructions, space frame structures have become increasingly commonplace. Using ETABS V19 and American Standards, this study modeled and analyzed the space frame structure. It measured 25 by 25 meters. Standard ASTM A36 and A36 grade steel sections were ASIC-14 HSS3X0.250 and HSS 2.5X0.188. The built-in load combination was specified by American Standards. The proposed structure was analyzed using 18 load combinations derived from ETAB. The proposed structure's maximum deflection was 5.01mm under the load combination UDStlD2. The load combination UDStlS2 resulted in the maximum deflection of 7.26 mm. On the basis of an analysis of the shear force and bending moment envelopes for the proposed structure in terms of section strength, the major load combinations were calculated. The highest shear force and bending moment values obtained for HSS 3 X 0.250 were both 0.1920KN, whereas for HSS 2.5 X 0.188, the highest shear force value was -0.03650KN and the bending moment value was -0.0296KN. The obtained results for shear force and bending moment for both sections show that the both HSS section are internally stronger to resist the bending stress in terms of strength with different load combinations. The obtained P-M ratios values lies between 0.5 to 0.70 at the mid- sections and 0.0 to 0.5 at side-sections. shows that the side sections of the proposed model are not economical. It indicates that the side section should be replaced with the smaller sections for economic structure.
Assessing the seismic vulnerability and refurbishing for reinforced concrete bridge
This research was aim to evaluate seismic susceptibility and rehabilitation of the reinforced concrete bridge. The seismic analysis and seismic response of the bridge under traffic load were analyzed in CSI Bridge 20 according to the AASTHO LRFD and HL-93 standards. A specific bridge of 60 meters in length and 15.5 meters in width was considered for analysis. The bridge was a concrete tee-beam bridge situated in Russia and had four lanes with piles in the foundation measuring 10 meters tall. It was discovered that 3520.03 KN-M was the maximum horizontal axis moment under load combo 1, and 4726.90 was the maximum bridge section stress. The maximum vertical displacement on the bridge span was 1.197E-03 metres, and the largest longitudinal displacement was 8.196E-04 metres. Additionally, Pushover analysis using the ASHTO LRFD 2012 code with built-in load cases determined the bridge's seismic design response. Bridge pier transverse and longitudinal bents were examined. The highest displacement was 42.27mm in pushover curve 7 under load case PO TR4 for bent 4 transversely. In Pushover curve 8, load case PO LG4 for bent 4 in longitudinal direction had 57.25mm displacement. Moreover, the Modal analysis examined how earthquakes affect bridge observation frequencies and times. Six deformed shapes' periods and frequencies were examined first. Mode 5's deformed shape responds well to the bridge's elastic property with
Stability analysis of reinforced concrete slender column
In this research, a complete study was made on three types of universal codes (ACI 318M-19, BS-8110 and TS500) that are used in the analysis and design of slender concrete columns.168 rectangular concrete columns (HSC, NSC) available in literature. Several types of columns, short and slender columns with sway or non-sway frames. A case study of 12096 concrete columns with specific values for the variables affecting on the bearing capacity of the column, the behavior as well as the stiffness. Existence some of constants in the standard equations leads to inaccuracies in the results. Therefore, this constant will changed to equations will be proposed that include some of details of columns like the amount of steel ratio, the dimension of the section... etc. Two formulas and one value are suggested in the analysis procedure to obtain the most accurate value of bearing capacity and the lateral deflection of the column. Matlab 2020a program was used to calculating all details of each column. The accuracy in this program gives the exact values of the results. Also Microsoft excel 2020 program used for modeling, scheduling and comparing all results.
Beton basınç dayanımı tahmini için yeni bir model
Concrete is the utmost chief material in civil engineering. The concrete compressive strength is a highly nonlinear function of age and ingredients. In this thesis, effect of water, gravel, sand, blast furnace slag, plasticizer, and the effects of flay ash on concrete compressive strength was presented by using Long short-term memory (LSTM). Artificial recurrent neural network (RNN) architecture used in the field of deep learning. Unlike standard feedback neural networks, LSTM has feedback links. The concrete compressive strength is regression problem which several classical artificial intelligence and machine learning techniques applied to solve it. In this study, the model consist from eight input and one output which represented the concrete compressive strength.
Numerical modeling of rc deep beams strengthened by FRP in Abaqus
Although in the last two decades the Fiber Reinforced Polymer (FRP) has been widely considered as an applicable material to strengthen and rehabilitation of reinforced concrete beams, there are a lack of investigation about the effect of this method on the strengthening of the reinforcement beams with web openings. However, some experimental and numerical investigations have been established to analyze the influences of these materials, but further comprehensive studies need to be done. In the current paper the effect of Basalt FRP (BFRP) layer as a strengthening additive on Reinforced Concrete (RC) deep beams with opening have been investigated. Furthermore, the flexural behavior of RC deep beams with opening strengthened by BFRP, and RC beams without opening have been studied using ABAQUS Finite Element Method (FEM) software. To this end, one reinforced concrete beam specimen was any further strengthening and two RC deep beams with circular and rectangular opening strengthened by BFRP were analyzed. The results of numerical analysis and simulations confirmed the positive influ nce of the fiber reinforced polymer (FRP) laminates as the strengthening additive on RC deep beams with opening.
Investigation of the SFRC two-way panels behavior under high temperature
reinforced concrete slab is an essential structural element which is used to provide building surface a flat form in different structural components. the high temperature affects steel reinforced slabs punching resistance. In this study, the experimental work using a model of SFRC panels was carried out to study the two-way panels of SFRC under high temperature using ANSYS software. The experimental program marked as four groups in which each group contains one panel without steel fiber and three panels of different percentages of steel fiber panels. The specimens are 3D configuration of slab concrete with the dimensions of 500 × 500 × 60 mm using four deferent steel fiber percentage, they are (V_f= 0, V_f= 0.75, V_f= 1, V_f= 1.25). the results observe that adding fiber led to lower deflection values and the best deflection value is obtained from adding 0.75% of steel fiber under the ambient condition with load (40 KN). While at high temperature the best deflection value is obtained from adding 1% of steel fiber at 100 °C..
The fair progress of the construction project and the conflict settlement between the client and the contractor
Because of their effectiveness, Engineering Contracts (EC) are considered by both parties to be the project execution plan that serves the goal for which the contract is formed. However, there are some conflicts that the contract does not fundamentally resolve, causing the two parties to resort to the judiciary, dispute resolution panels, and other alternative remedies. This study aims to clarify most of the solutions that are included in the contract stage as it is the most critical stage in the project until its perfection according to what is required to limit the outbreak of disputes between the contracting parties, which may develop into a conflict by dividing the study into two frameworks, the first is theoretical and includes a comprehensive study of the stages. To complete the project from feasibility to delivery and documentation and information about conflicts, their causes, how to avoid them, disagreements, their divisions, and how to settle them. The second framework is practical. It consists of a questionnaire data from the field of study and the reality of the problem, as well as research hypotheses, where the data was reviewed and discussed to arrive at some conclusions that will aid in the solution of the problem. To avoid the occurrence of disputes from the stage of concluding the contract and therefore obtain recommendations to support the research, reducing disputes in the Construction Industry (CI) and designating decision-makers in the general policies of the profession represented in it is essential. When signing contracts without consulting legal departments, there is a significant impact, as it is the cause of problems in the project stages. After the bid is sorted, the contracting contract is well formulated due to the importance of the contract language and formula, as it must be following the law, and the contract form differs depending on the type of contract. The engineering contract's clauses define each party's role and responsibilities and state that there will be no contractual problems unless there is a lack of suitable and thorough project study with comprehensive preliminary drawings before signing the contract and failing to give the essential measures for extra work. The reason for a contract dispute's occurrence.