Civil Engineering
238 theses under this subject heading
Effects of Limestone Powder, Olive Waste Ash and Sea Sand Powder on Properties of Self Compacting Concrete
Utilization of standardized local and waste resources is of great importance to the economic development in the world. Besides, application of waste material results in more eco-friendly concrete at the same time. In this study, the effects of two different new fillers, named as sea sand powder (SS), as a local available material and olive waste bottom ash, (OW) as a waste material of different proportions incorporated with two different quantities of superplasticizer (SP), on physical and mechanical properties of SCC were aimed to be investigated and compared to those of limestone powder (LS) as a common filler. For these aimes rheology of fresh concrete, compressive and tensile strengths, initial defects, fracture energy and volume changes during hydration were measured. Results showed that there is no considerable difference in hardened properties of SCC by using SS instead of LS; however, differences in volumetric shrinkage and rheological properties, especially for bleeding and segregation, were more pronounced. On the other hand, OW mixes show different outcomes. OW gives more viscosity to SCC mixes and eliminates segregation and bleeding of the mixes containing this filler. Nevertheless, reduced compressive strength and fracture energy and increased volumetric shrinkage and porosity in these mixes were noticeable compared to LS mixes; however, when 5% OW was used, the results found to be more tolerable. Keywords: Self-consolidated concrete, Olive waste ash, Sea sand powder, Limestone powder, Compressive strengths, Fracture energy
Effect of High Density Polyethylene Plastic (HDPE) and W/C Ratio on Fresh and Hardened Properties of Self-Compacting Concrete
In this thesis, the effects of High Density Polyethylene (HDPE) aggregates are studied on fresh and hardened properties of self-compacted concrete (SCC). Therefore, 5 different replacement levels of HDPE with coarse aggregate namely 0 %, 5 %, 10 %, 20 %, and 30 % by volume. In addition, superplasticizer (Glenium 27) and silica fume were added to SCC mixtures by 1.7 % and 10 % by weight of binder, respectively. Slump flow, L-box, and V-funnel tests were performed on the 5 different mixtures to study the workability of SCC. Compressive strength, splitting tensile strength, flexural strength and toughness tests were utilized to study the mechanical properties of the SCC mixtures, while plastic degradation at 100 and 200 °C temperatures, ultra-sonic pulse velocity, and surface cracks observations to determine the durability of the SCC mixtures. After these tests are performed, the results reveal that it is possible to produce self-compacted concrete using HDPE up to 30% replacement level. However, incorporation of HDPE in self-compacted concrete has negative effects on the properties of SCC, decrement in workability, compressive strength, splitting tensile strength, flexural strength, UPV, and it causes surface cracks. On the hand, adding HDPE in SCC has positive effects as well, since it increases the ductility of SCC, and reduces the self-weight of concrete which is promising to produce light-weight concrete. Keywords: high density polyethylene (HDPE), self-compacting concrete (SCC), silica fume, workability, mechanical properties, compressive strength, splitting tensile strength, ultrasonic pulse velocity (UPV), flexural strength, toughness.
Seismic Assessment and Retrofitting of Existing RC Building by Using Steel Braced Frames
Antakya city is in danger as a result of solid seismic actions happening in the territory, and diverse soil conditions that can create a variety of the ground motion amplification. In recent years, scientists and engineers have started to assess the existing structures and their behaviors in resistance to lateral loading, potential earthquake hazard, and vulnerability. Existing structures can be retrofitted to incorporate new improvements and techniques to oppose quake and seismic burdens, which was the most efficient approach to shield against the financial and social disaster influenced by serious seismic action in urban areas. This thesis presents a study on a five-storey reinforced concrete structure was built in 1988 and located in Antakya, Turkey. This work consists of three phases. The first stage, data collection which includes building plans, material properties, structural condition, and reinforcement details. Material properties are measured using non-destructive testing method called model calibration. The model calibration is obtained from building dominant periods and mode shapes of the existing building, which have been measured using forced vibration tests. In the second stage, the analytical modeling of the structure is made using SAP2000. After model calibration, the nonlinear static pushover analysis for the seismic performance evaluation based on the ATC-40 methods has been obtained. Finally, the existing building, which showed low performance according to code requirements, is strengthened by using two different types of external steel brace frames. They have been attached to Y-direction, which has poor performance for both sides until the second floor, and recommended that this strengthening technique is an appropriate method according to the performance and cost analysis. Keywords: Evaluation earthquake, Pushover analysis, Retrofitting, Forced vibration
Experimental Study on Some Properties of Recycled Polypropylene Plastics as a Partial Replacement of Coarse Aggregate in High Strength and Normal Strength Concretes
Previously, various studies were performed to identify safety and environmentally friendly methods for disposing of plastics. Recently, various forms of plastics have been incorporated in concrete to prevent direct contact of plastics with the environment because concrete has a longer service life. In this thesis, the effects of coarse aggregate replacement of Polypropylene as a waste material on fresh and hardened properties of normal strength concrete (NSC) and high strength concrete (HSC) was investigated. To do so, different percentages of polypropylene were replaced by various volumes (0%, 10%, 20%, 30%, 40% and 50 %) of normal and high strength concretes, with the water to cement ratio of 0.58, 0.34 for normal and high strength concrete, respectively. In addition, Superplasticizer (Glenium 27) was added to the NSC and HSC mixed by 0.3% and 2% cement weight, respectively. Slump and VeBe time tests were done to analyse the physical properties of fresh concrete. Moreover, the influences of PP replacement in the hardened concrete were executed by performing splitting tensile strength (fs), compressive strength (fc) and flexural strength (ff) tests. Rapid chloride permeability (RCP), heat degradation at 200 °C, water absorption, and non-destructive tests such as Ultrasonic Pulse Velocity (Pundit) and Schmidt hammer (rebound) were also conducted. The results showed changes in mechanical properties of normal strength concrete and high strength concrete as the percentages of PP increases. The amount of fs, fc, and ff of normal and high strength concrete decreased with the increase in the amount of polypropylene at 28 days. Furthermore, high water absorption was observed with the increasing of PP. According to the results of the Pundit test the replacement of Polypropylene increased the quality of concrete up to 50% in comparison with the control samples. It is worth noting that negative effects in fc, fs, ultrasonic pulse velocity, and crack development were observed after 200 °C heat exposure. Keywords: Polypropylene (PP), Normal strength concrete, High strength concrete, workability, Mechanical properties, Non-destructive test, Water absorption, Permeability, Heat exposure
Mechanical Characteristics Investigation of Ultra High Performance Concrete Using Design of Experiment and Response Surface Methodology
Attention to the mechanical properties of concrete for higher strength and ductility and also the increase in its durability has resulted in the innovation for several types of concrete. Ultra high performance concrete (UHPC) is one of the latest concrete with the unique properties such as high compressive strength, exhibiting tensile and flexural strength with increase in energy absorption (toughness), high durability, improved resistance against freezing- thawing and various chemical attacks. UHPC represents the highest development of high performance concrete in different curing conditions. One of the main disadvantages of UHPC is huge amounts of binder content used for producing UHPC. The purpose of this study was to improve the mechanical properties of UHPC relative to using local materials in two different phases: The purpose of phase one was to find the models of 7, 14 and 28-day compressive strength, 28-day splitting tensile strength, modulus of rupture, and flexural toughness of Ultra High Performance Concrete, as well as, study on the interaction and correlation of five variables including silica fume (SF), cement, steel fibers, superplasticizer (SP), and w/c ratio. The models are valid for mixes made with 1.0 part sand, 0.15-0.30 part silica fume amount, 0.70-1.30 part cement amount, 0.10- 0.20 part steel fiber, 0.04- 0.08 part superplasticizer (all values by sand weight) and 0.18- 0.32 water cementitious material ratio. In phase two, the effect of quartz powder (Qp), quartz sand (Qs), and different water curing temperatures on UHPC performance was investigated, the correlation between these variables and mechanical properties were found. The offered models are valid for the variables between: quartz powder 0 to 20% of cement substitution, quartz sand 0 to 50% of aggregate substitution, and water curing temperature 25 to 95 ºC. The experiments were designed by central composition with α=1 (face centered). The response surface methodology was analyzed between the variables and responses. The correlation of variables and mathematical models in terms of coded variables were established by ANOVA. Keywords: Ultra high performance concrete, strength, durability, silica fume, steel fiber, quality sand, modelling.
Probabilistic Seismic Demand of 2-D Steel Moment Resisting Frames in Estimation of Collapse under Earthquake Ground Motions
ABSTRACT: This study concentrates on evaluation and estimation of collapse of two 3-story and 9-story steel moment resisting frames designed by SAC/ FEMA for the place of Los Angeles California. “Collapse” in this research is defined as the loss of lateral load-resisting capacity of frame structural system by the application of ground motion and by considering P-Δ effects on the dummy column. Dummy column is connected to the steel moment-resisting frame in order to consider the effects of gravity loads of the real 3-D structure while 2-D frame is extracted from 3-D frame. Estimation of collapse performance requires the relation between a ground motion intensity measures (IM) and the probability of collapse defined as collapse fragility curve as well as the relation between the same ground motion IM and the seismic hazard for the building defined as seismic hazard curve. Among two methods of estimating the collapse fragility curve; IM-based and EDP-based, the first method is carried out in this research because of its better performance in collapse limit state according to the previous research. In this approach, collapse is associated with ground motion IM and it is obtained by using Incremental Dynamic Analysis. The collapse performance criteria that are obtained from this research are compared with the collapse performance criteria recommended by Haselton and SAC/FEMA guidlines. Keywords: Incremental dynamic analysis, Fragility curve, Mean annual frequency, Seismic Hazard Curve, Probabilistic. ……………………………………………………………………………………………………………………………………………………………………………………………………………………
Assessment of Reusability Potential of Reinforced Concrete as Waste Material via BIM: A Case Study of Office Building EMU Faculty of Architecture
Construction sector can be counted as the main problem of consuming resources and waste generation throughout the world (Zhang, C., et al., 2021). It has a negative impact on land deterioration, solid waste production, energy consumption, emission of gas, natural resource consumption (Lu, W., Yuan, H., 2011). As stated by the report by Environmental Protection Agency in 2017, 569 million tons of Construction and Demolition (C&D) waste was generated in the United States, however only 40% of C&D waste that comes from buildings is reused or recycled, while 35% of worldwide C&D waste sent to be landfilled. It is vital to understand that C&D waste has a great potential of reuse and recycling (Guerra, B. C., et al., 2020). C&D waste generation can be originated with man-made sources and nature-made sources. It can be accepted as public works construction and maintenance, building construction works, and building renovation and demolition works. Nature-made sources of C&D waste on the other hand, can be accepted as natural disasters such as earthquakes, floods, hurricanes, and tsunamis (Menegaki, M. & Damigos, D., 2018). Research on C&D waste management has been conducted globally in an attempt to mitigate the harm that the construction sector causes. Building Information Modelling (BIM) has been increasingly effective and accepted construction methodology in recent years (Nikmehr, B., et al., 2021). BIM can be defined as a digital depiction of a facility’s functional and physical attributes (Kylili, A. & Fokaides, P. A., et al., 2015). According to the National Institute of Buildings Sciences (2014), a BIM model is shared knowledge resource that contains information about a structure that can be trusted as a reliable base for choices made through its lifecycle. BIM enables the integration of energy-efficient design into the evaluation of energy use over the building life cycle. Incorporating BIM technologies with Life Cycle Assessment methodology is one of the proposed strategies according to many academics, to analyze environmental consequences in the building sector (Najjar, M., et al., 2017). This thesis provides a literature review through the current situation of concrete as C&D waste material. It aims to understand the reusability and recyclability potential of reinforced concrete material that being used as structural elements by using visualizing it BIM program Autodesk Revit in corporation with One Click LCA program to achieve building circularity assessment. It concludes the study with interpretations for reusability and recyclability state of reinforced concrete material out of the results that obtained from One Click LCA building circularity report. The main aim is to compare the reuse, recycle, landfill options for reinforced concrete material of the selected case and give a sustainable solution for the projects to be demolished and reconstructed. Keywords: Building Circularity, Reinforced Concrete, Waste Concrete, Material Reuse, Building Information Modelling (BIM).
Development of Load and Resistance Factors for Reinforced Concrete Structural Members in North Cyprus
Load and Resistance Factor Design (LRFD), is a widely used procedure in the design of reinforced concrete, wood and steel structures. It is a reliability-based procedure for design, which gives a framework that is consistent with civil engineering design codes, in accordance with reliability theories. In this study, Advance First Order Second Moment (AFOSM) approach is used as the reliability approach in carrying out the analysis. Uncertainties related to material properties (i.e. compressive strength of concrete, yield and ultimate strength of reinforcing steel bars.), dimensions of reinforced concrete structural members (beams and columns) and the effect of load variables (i.e. Dead and Live load), are considered. Under the framework of AFOSM the failure mode in different reinforced concrete structural members were analyzed, which focused mainly on flexure failure, shear failure and the combined action of flexure and axial load failure. Reliability indexes are calculated according to the flexure and shear failure modes in beams and columns, in addition to failure due to the combine action of flexure and axial load on columns. Target reliability indexes are selected for different load combinations from values reported by other researchers from different countries, which are used as the safety level to evaluate the computed reliability indexes. New load and resistance factors are selected for different failure modes in different structural members, considering the design practice in North Cyprus and specifications given in the Turkish codes (e.g. TS500). Keywords: Model Uncertainty, Reliability, LRFD, Reliability Index, Safety Level
Principles and Practices of Seismic Isolated Buildings
ABSTRACT: Earthquake design philosophy based on capacity, directs the following two unpleasant states: 1. The situation that continues to increase the elastic strength and stiffness; in fact this is not economical and also cause higher floor accelerations. 2. The situation that limits the elastic strength and increasing ductility by detailing; indeed this approach is the acceptance of non-repairable structural damages. Base isolation is a different approach than the mentioned ones. It is based on the concept, which reducing the seismic demands rather than increasing the earthquake resistance capacity of the structure. On the other hand, application of base isolators to the structure reduce elastic base shear by shifting period of the structure and provide better performing structure that will remain essentially elastic during large earthquakes. However, in this thesis, general information about seismic isolated structures such as type of isolators, world-wide applications, practical applications, properties, code requirements and different processes required for designing various seismic isolators are discussed. Then, 3 different buildings (3, 6 and 9 story) which were isolated by 3 various isolators (Lead Rubber Bearing, High Damping Rubber Bearing and Friction Pendulum System) were analyzed by applying dynamic response spectrum analysis, as a linear elastic analysis method, to evaluate the optimum one according to the seismic demands. Transmitted acceleration, maximum structural displacement and seismic coefficient for each building were shown in the different graphs. Furthermore, the 3 story optimum isolated building was compared with its conventional fixed base one in performance and material. Based on obtained results, it could be inferred that Lead Rubber Bearings represent minimum transmitted acceleration and seismic coefficient among other types. Low effective stiffness and high damping which is represented by Lead Rubber Bearings are the most important factors for this minimization. Structural displacement is minimized by Friction Pendulum Systems due to the high friction of coefficient which they produce. In addition, in rubber bearings transmitted acceleration and structural displacement is affected by damping of isolation system. Furthermore, in the comparison process of base isolated building with its conventional fixed base one , it is concluded that application of the base isolators to the structure increase cost of the building around 5.8 % of total cost. Keywords: Base isolation, Isolator, Cost, Earthquake, Strengthening. …………………………………………………………………………………………………………………………………………………………………………………………………………………… ÖZ: Sismik Taban Yalitimli Binalarda Temel Prensip ve Uygulamalar. Kapasiteye dayanan deprem tasarim felsefesi bizi asagidaki iki kötü seçime yönlendirmektedir: 1. Elastik dayanimi sürekli olarak artirmak; Bu yaklasim ekonomik degildir ve yüksek kat ivmelerine sebep olmaktadir. 2. Elastik dayanimi sinirlandirmak ve detaylandirarak düktiliteyi artirmak; Bu yaklasim ise ileride binada tamir edilemeyecek yapisal hasarlarin kabülü sayilir.Sismik taban izolasyonu yukarida belirtilenlerden farkli bir yaklasimdir. Yapinin deprem direnç kapasitesini artirmak yerine sismik talepleri azaltmaya yönelik bir yaklasimi temel alir. Diger taraftan, yapiya taban yalitiminin uygulanmasi yapinin periyodunu kaydirarak elastik taban kesme kuvvetini azaltir. Bununla beraber büyük depremlerde esasen elastik davranisi koruyan daha iyi bir yapi performansi saglanmis olur. Bu tez çalismada izolasyon sistemleri, dünyadaki uygulamalari, pratik applikasyonu, özellikleri, yönetmelik esaslari ve degisik izolatörlerin tasarimi gibi konularda detayli bilgi verilmistir. Daha sonra ise degisik kat yüksekliklerine sahip (3, 6 ve 9), 3 ayri binaya 3 farki tip taban izolatörü (kursun çekirdek mesnet sistemi, yüksek sönümlü dogal kauçuk mesnet sistemi ve sürtünmeli sarkaç sistemi) uygulanarak response spektrum analizi yapilmistir. Farkli grafiklerde maksimum kat ivmeleri, maksimum deplasman ve taban kesme katsayilari karsilastirilmistir. Son olarak 3 katli ankastre ve izolatörlü yapilar performans ve malzemeye dayali olarak karsilastirilmistir. Elde edilen sonuçlardan yola çikarak kursun çekirdek mesnet sistemi digerleri arasinda minimum ivme ve sismik katsayiyi vermistir. Yüksek viskoz sönüm ve düsük rijitlik özellikleri bunu saglayan en önemli faktörlerdir. Yapisal deplasman sürtünmeli sarkaç sisteminde yüksek sürtünme katsayisina bagli olarak minimize edilmistir. Buna ilaveten, kauçuk mesnet sistemlerinde ivme ve yapisal deplasmanin izolasyon sisteminin viskoz sönümden etkilendigi söylenebilir. Sonuç olarak ankastre ve izolatörlü yapilar arasinda yapilan karsilastirmaya dayali olarak temel izolatörlü yapilarin toplam maliyeti 5.8% artirdigi gözlenmistir. Anahtar Kelimeler: Taban izolasyonu, Izolator, Maliyet, Deprem, Güçlendirme.
Assessment of Two Sets Intensity Measures of Ground Motion with Seismic Damage Indices of Masonry-infilled Steel Frames
The objective of this study is to investigate the nonlinear behavior of two dimensional 3, 5, 8 and 12 story steel frames with and without masonry infill considering the intensity measure (IMs) parameters of near-fault ground motions and dynamic Soil-Structure Interaction (SSI).A single story and single bay steel frame numerical model was validated by using two software, SAP2000 and OpenSees and comparing the structural periods obtained. Then the validation of OpenSees numerical model against the experimental results from literature was done. This was followed by using the validated models to create the rest of the numerical models. Aspect ratio of the superstructure and non-dimensional frequency are selected as the main parameters for the soil-structure system. Two sets of earthquake ground motions, ordinary seismic records (OSR) and pulse-like seismic records (PLSR) were used for the nonlinear dynamic analysis. Seismic performance was evaluated using the general indicators of damage (modified Park-Ang index), maximum inter-story drift ratio (MIDR) and roof drift ratio (RDR). The correlation between the multiple IMs with and without pulse-like seismic excitation and the damage indices of 3 forms of steel moment frames; bare, partially and fully infilled was determined using the Spearman correlation coefficient. Also, a significant part of correlation between the damage criteria and IMs was assessed. It was concluded that the spectral acceleration (Sa) and velocity (Sv) of the structures period strongly correlated with MIDR and RDR and that velocity correlated with the seismic parameters. The correlations for PLSR and OSR differed for each case and IMs with ground motion can help predict the parameters for building failure in various systems. In most ground motion parameters, the presence of masonry-infilled walls decreased the correlation coefficient for a fully infilled frame when compared to a bare frame. It should be noted that GSDI has high correlation with MIDR than with RDR. The correlation coefficients with the effect of the SSI were reduced by a range of about 10-20% for a model frame with flexible base when compared with the same model with a fixed base. Therefore, the use of PLSR is important when SSI is considered, since it generally negatively effects the correlation of damage indexes and causes considerable change in the behavior of partially infilled and fully infilled frames with respect to bare frames and high rise with respect to low rise frames. Keywords: Intensity measures, Ordinary records, Pulse-like records, Damage index, Steel frame with masonry infill, Soil-structure interaction
Influence of Matrix Quality and Environmental Conditions on Volume Change and Microcracking Behavior of Concrete
Concrete is a highly complex and heterogeneous engineering material. In its complex composite structure, it is not easy to understand its behavior either during hydration process or loading the material. Particularly the volume change during hydration results in initial defects and at the end these defects may influence its mechanical behavior under load. Individual properties of different phases like aggregate, matrix and the interfacial transition zone (ITZ) between the two, plays an important role on the microcracking behavior of the concrete. In this study, various techniques were used in determining the effect of hydration shrinkage crack on the microcracking behavior of the concrete including w/c ratio, silica fume and environmental conditions. Direct measurement by means of optical processing through Scanning Electron Microscope (SEM) is a way. On the other hand, the indirect measurements dealt with an overall study of the material by means of the tensile and the compressive strength measurements, the length and the volume change measurements and the prediction of the critical crack load from stress-strain diagrams. Conclusions were drawn from the direct and the indirect methods. The ultimate purposes of all the performed tests were used to measure the initial defects either in the ITZ or the matrix and their effect on the whole microcracking behavior of concrete. Keywords: SEM, ITZ, Cracks density, Compressive strength, Tensile strength, Volume change, Shrinkage.
Experimental and Numerical Investigation on Steel Fibrous Reinforced Concrete Slab Strips with Traditional Longitudinal Steel Bars
ABSTRACT: The aim of this thesis was to investigate the influence of steel fibers on mechanical performance of reinforced concrete slab strips based on experimental and theoretical research. Two different types of fibers that are having aspect ratio 60 and 80 have been employed with 4-four diverse volumetric percentages of 0.5, 1.0, 1.5, and 2.0% fibers. All the fibrous specimens have been compared to reinforced concrete slab strips without fibers and with identical longitudinal reinforcement. The flexural tests have been performed on slab strips to examine the effects of fibers on flexural improvement of specimens, and energy absorption enhancement. The dimensions of slab strips have been chosen to observe the flexural failure and prevent the shear failures. The results of experimental study have indicated that presence of fiber has been a significant influence on flexural performance and energy absorption. In theoretical modeling, by using the constitutive model of material that suggested by previous researchers and standards, the slab strips have been modeled via a FEA software namely, Abacus and analyzed. The results of numerical modeling have illustrated that the constitutive models are compatible with experimental test results quite satisfactorily. The experimental load-deflection curves verified that numerical stress-strain relationships for fibrous concrete material could be utilized for specimen with interaction by traditional reinforcement. Keywords: Steel fibers, Reinforced concrete, Flexural strength, Energy absorption capacity. ……………………………………………………………………………………………………………………………………………………………………………………………………………………
Integration between Building Information Modeling (BIM) and Energy Performance Modeling to Analyze the Effects of Building Shape and Orientation on Energy Consumption
ABSTRACT: Beneficial influences of Building Information Modeling (BIM) and energy performance modeling in construction projects have been separately recognized and proved. Furthermore, modern methods of construction necessitate a concurrent approach to improve the efficiency and effectiveness of decision making procedure in very beginning of design stage. Hence, integration between BIM tools and energy simulation software can result in a significant saving in energy and cost. Due to the fact that many attempts have been made to develop sustainable and cost-effective design, analyzing and optimizing shape factor and building orientation as two highly effective design parameters can contribute to addressing such issues. These two factors are feasible and inexpensive to be considered in early design phase when there are lots of alternatives to choose. In this research the considerable impacts of orientation and shape factor on thermal load were elucidated and demonstrated through the integration of BIM and energy analysis tool. During the investigation the appropriate orientation of implementing construction in Cyprus was obtained. Also the optimal proportion of wall area in north-south to east-west was determined. Keywords: Building Information Modeling (BIM); Thermal Modeling; Building Shape; Orientation …………………………………………………………………………………………………………………………
Seismic performance evaluation of 2-Dimensional reinforced concrete, steel and mixed frames
ABSTRACT: It is well known that, Turkey and Cyprus are in high seismic activity zone. Therefore designers should consider the seismic effects according to described earthquake. Reinforced concrete and structural steel are the two main materials that are used in construction industry. However, these two materials possess different characteristics in their behavior. In recent years structural steel has become more popular due to some of its characteristics such as being light, ability for being prefabricated, fast erection and ductility levels. Nowadays, with lack of space for the development of cities multi-story structures are more in favor by the building developers and contractors. Demolishing old structures and constructing new high-rise buildings are not always the optimized solution from economic point of view. In recent years using light materials to build extra stories on existing structures is believed to be a good option for the solution of load problem. Under static loads there may not be any serious concern. However the analysis and assessment of seismic performance of these mixed-material frames would be different when compared to conventional structures. Designing such structures would be a challenging task since current design codes do not support the analysis and design solutions for the structures having frames with different damping ratios. The scope of this work is to evaluate the seismic performance of mixed and regular structures. For this, the mixed structural models considered had two parts; a lower part constructed from reinforced concrete and the upper part made constructed of structural steel. In order to investigate and evaluate the seismic performance of mixed structures and compare the results with those of normal structures, the nonlinear time history analysis method was used including geometric and material nonlinearities. In order to achieve a reliable comparison the response of mixed structures under dynamic loads were investigated together with normal structural steel and reinforced concrete structures. Comparison of the results showed that changing the story numbers or structural materials will cause contrasting results. Plain frame dynamic analyses were performed on three different frame structural models. Two regular framed models; fully reinforced concrete and fully structural steel were designed according to codes and the third one was created by combination of the other two models. Keywords: seismic performance, mixed structure, composite framing, time history, dynamic analysis. …………………………………………………………………………………………………………………………
Investigation of space truss using the integrated force method
ABSTRACT: This thesis investigates the usage of integrated force method in the analysis of statically indeterminate space truss. Computer codes are written to generate the equilibrium equations and then calculate the unknowns as: internal forces, nodal displacements, deformations and support reactions. The first two programs of space truss analysis find the member forces in statically indeterminate cases. These two programs are based on integrated force method (IFM) which recently developed as solution approach. The main step of integrated force method is obtaining of compatibility condition and the difference between these programs is related to the calculation of compatibility condition. In the first program null space of equilibrium equation is used to find the compatibility condition and in the second program singular value decomposition is used. The third program is based on displacement method termed dual integrated force method. In this method the main step is generation of global stiffness method which is assembled by the matrix multiplication of the equilibrium equation, its transpose and the diagonal matrix of the inverse of the flexibilities of members. In this method displacements are primary unknowns and internal forces can be back-calculated. Keywords: equilibrium equation, integrated force method, dual integrated force method. …………………………………………………………………………………………………………………………
Effects of Some Stakeholders on the Briefing Design Stage in Construction Projects
In the construction industry, one of the risk areas is lack of planning and management on the project budget, project time, and the project scope in the briefing design stages of the construction project between the stakeholders. The briefing stages of the design project is divided into three parts; identification of the project, aim and content of the project, and design and performance of the project. In these parts, determination of possible risks and problems between client and design team plays a very important role in achieving the construction project design. This research focuses on the determination of the potential risks between design team members (who takes the lead on the construction project design e.g architects and engineers) and clients (any person for whom construction work is performed). Also this research provides an instructing expert system to increase both the safety of clients and achieving the design team activity by sticking to the problems early in the briefing design stage. Keywords: Briefing design stage, Client, Design team, Construction project, Expert system
Management and Structural Aspects of Creation of Sustainable Smart Cities
In light of the exponential rate at which urbanization is accelerating, the smart city concept has gained more attraction worldwide. Smart cities use the latest technologies, sensors, and various monitoring tools in their infrastructure and smart buildings and adopt green sustainable practices in all of their sectors to improve their operational efficiency, sustainability, safety, and disaster resilience while providing the best access to different services and enhancing the quality of life of their citizens. To some extent, the smart city movement has been limited to developed countries, primarily due to several obstacles that may prevent developing countries from implementing smart city initiatives successfully. The research in smart cities initiative, especially in the field of civil engineering is relatively new and is developing rapidly and continuously and is expanding to include more areas in construction and building techniques. The aim of this study is to identify the key factors affecting smart cities from sustainability and disaster management aspects and propose some strategies for improving the more effective factors. For the identification of more important factors a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis is used. First, a questionnaire survey technique is used to determine the relative importance of these factors. Then, a TOWS matrix is conducted to find the relationship between the SWOT's external and internal factors and draw strategies accordingly. Specifically, this thesis aims to draw strategies for developing countries to take advantage of smart cities' strengths and opportunities while minimizing their weaknesses and threats in two areas of sustainability and disaster management.
Primary Study on Ureolysis-Based Microbially-Induced Calcium Carbonate Precipitation Technique for Geotechnical Applications
Environmental concerns and application limitations of the conventional techniques for geotechnical engineering problems persuaded the geotechnical engineers to look for alternative solutions. In this regard, biogeotechnics which deals with bio-mediated and bio-inspired solutions to the challenges that vex geotechnical systems has been recently introduced. Within only around one decade of emerging this topic, it has received many attentions by researchers as it offers the promise of cost-effective, sustainable and non-disruptive solutions for a diversity of geotechnical applications. Microbially induced CaCO3 precipitation (MICP) is one the biological solutions, through which calcium carbonate is precipitated as binding agent between grains and/or filling materials within soil pores, by mediation of microorganisms. Successful development and implementation of the MICP technique for ground improvement would have wide application to many important geotechnical problems, such as increasing stiffness and shear strength to mitigate liquefaction potential; to enhance bearing capacity of soil beneath foundation and reduce associated settlements; to stabilize slopes; to facilitate excavation, boreholing and tunneling; to control erosion; and reducing permeability to reduce seepage of dikes and cut-off walls. Application of this technique may be especially useful underneath or near existing structures, where the application of conventional soil improvement techniques is restricted due to high cost or ground deformation associated with available technologies. There are several mechanisms for MICP. Ureolysis mechanism is the most concentrated one in the literature, in which ureolytic microorganisms are employed as biological mediators. Since introducing the ureolysis-based MICP into geotechnical engineering, many researches has been carried out on development and application of this technique into soil at laboratory scale. Although much success and progress have been attained by these studies, it was found that there is still lack of some geotechnical insights in biology-oriented side and some biological insights in geotechnics-oriented sides; for instance, no cheap, fast and geotechnical engineer-friendly method for estimation of precipitation progress was presented; and few attention has been also paid to the mineralogy of the precipitated calcium carbonate as it can influence mechanical properties of the treated soil and durability. In the present study, a hybrid of conductometry and precipitation mass measurement method in treatment solution (Biogrout) has been developed for monitoring the precipitation progress, which facilitates controlling over precipitation pattern, i.e. estimation on type, time, amount and place of precipitation within soil. It was found that the precipitation pattern in every treatment solution follows a logistic function, which was herein designated as microbial CaCO3 precipitation characteristics curve (MCPCC) since it represents three important characteristics (i.e. precipitation rate, precipitation ratio and lag duration). Effect of some significant influencing factors on these characteristics was investigated. Statistical models for precipitation rate and ratio were also presented. Potential type and morphology of the precipitates at different environmental conditions have been also assessed. It was observed that calcite as the most stable type of calcium carbonate does not always occur. Formation of non-stable phases can cause change in mechanical properties of treated soil as change in type and morphology of the precipitates during time was demonstrated in this study. Treatment of soil samples by using soaking and injection methods at high and low rate of precipitation were also separately evaluated. Different soil treatment methods were found to influence the mineralogy, shear wave velocity and unconfined compressive strength.
Health and Safety in Construction Industry of Lebanon
A labourer at a construction site is bound to have certain rights, such as, right to return home safe and sound and to be taught how to maintain his and his colleague’s safety against potential hazards and risks associated with his position. Thus, enforcement of Occupational Health and Safety (OHS) standards at workplace is essential to prevent the work accidents and harm to labourers. The essence of the requirements and principles of OHS generally involves showing gratitude and respect towards the employee as a human being since he plays a very important role in achieving economical and communal development. The objective of this study is to investigate the status of OHS and its standards in Lebanon. In order to achieve this objective, three different surveys are prepared with the aim of getting sufficient OHS related information from public, employers and labourers. Construction sites, International Labour Organization, engineering union and construction workers union are visited to investigate the matters relating to OHS through meetings with those in charge. In addition, the laws and by-laws related to the OHS are explored and listed. The gathered information is analyzed to interpret the status of OHS in Lebanon. Finally, recommendations towards establishing and enforcing relevant rules to reduce and/or prevent the number of fatalities and injuries among labourers at construction sites, are presented. Keyword: Occupational health and safety in Lebanon, Lebanon Construction Industry, workers rights, standards, accident prevention.
Developing of Pavement Management System (PMS) for EMU Campus Pavement in GIS Environment
ABSTRACT: Systematic processes such as a pavement management system (PMS) are commonly utilized for assisting the decision making process in terms of finding a proper maintenance and rehabilitation (M&R) treatment for the pavement network. This kind of process usually can make sure of the effectiveness for funds that allocated for the treatment action. In this study PMS has been established for Eastern Mediterranean University (EMU) campus pavement network for both roadways and parking lots, which can be considered as a first step that carried out to establish this system for the campus. In this research, pavement evaluation study was undertaken in the context of phase a pavement condition survey producing pavement condition index (PCI) according to ASTM D6433 standard. PCI has been determined for every campus pavement section according to the existing pavement distress type, severity and quantity. MicroPAVER PMS software was utilized for computing PCI and for demonstrating when and which section of pavement network required (M&R) action. A total of 79 sections of the campus network were inspected and assessed in June 2012, it can be remarked that 37sections are in Excellent condition, 15 sections are classed as Very Good, 21 are classed as Good, 4 of sections are in Fair condition and 2 sections are classed as Poor. Moreover, there is no section observed in Very Poor or Failed condition, and also the average PCI for the whole pavement network is 79. Therefore, the entire campus pavement health can be classified as Very Good. The proposed plan was conducted for the coming 5 years which starts from 2013 to 2017. Additionally, the determined analytical results in PMS have been stored and displayed in Geographic Information System (GIS). This system is one of the latest techniques followed by using computers to save huge amount of data with large areas of the maps that cannot be saved properly on a paper. In this research ArcGIS10 was integrated with EMU campus PMS, GIS was utilized to assist in the preparation of a suitable database for the campus pavement network. For this reason a shapefile was created and an attribute table has been established. This table includes collected and computed pavement data such as: inventory, present and future condition, suggested treatments alongside costs for each individual section that required a treatment action. Finally, several reports, charts and thematic maps are produced. Keywords: Pavement Management System, Campus Pavement Network, Pavement Condition Index, Pavement Distress, MicroPAVER, Geographic Information System. …………………………………………………………………………………………………………………………
Effect of Specimen Size and Shape on Strength of Concrete
ABSTRACT: Testing the mechanical properties (especially compressive strength and tensile strength) of concrete is one of the most crucial stages of construction works. To control the quality of concrete, there are various moulds that are used for casting concrete samples during concreting works according to different standards at different countries. On the other hand, it is known that different shapes and sizes of concrete samples can cause variations in results of compressive strength or splitting tensile strength. This research concentrated on the effect of specimen sizes and shapes on compressive and splitting tensile strength of concrete, cured at different conditions and tested at both early and late ages. At the end of experimental study, hardened density, non-destructive tests (i.e. rebound hammer and PUNDIT), compressive strength and splitting tensile strength for different curing conditions were performed and some analyses were done to obtain conversion factors and relations among these factors and results. The results of analyses indicate that for all testing conditions, there is a strong influence of variation of size and shape of the specimens. In some cases, by changing the curing conditions, the change of trend of experimental results was not significant, for example the results of PUNDIT test. However, by changing testing age, there was a strong alteration in the results and their trends. Keywords: size effect, shape effect, compressive strength, splitting tensile strength, rebound hammer, PUNDIT, curing regime, conversion factors. ……………………………………………………………………………………………………………………………………………………………………………………………………………………
Improved Traffic Crash Modeling through Accuracy and Response Time Using Classification Algorithms: A Model Comparison Approach
ABSTRACT: This research focuses on predicting the severity of freeway traffic crashes by employing two different dataset including Iranian and Cyprus data. In Iranian data, twelve variables related to crash parameters were used by considering genetic algorithm, combined genetic algorithm and pattern search, and artificial neural network methods. The genetic algorithm evaluated eleven equations to obtain the best equation, and then the genetic algorithm and pattern search methods were combined using the best genetic algorithm equation. The neural network used a multi-layer perceptron architecture that consisted of a multi-layer feed-forward network with hidden sigmoid and linear output neurons that can also fit multidimensional mapping problems arbitrarily well. In Cyprus data, seven variables were selected to compare two fuzzy clustering algorithms—fuzzy subtractive clustering and fuzzy C-means clustering— with a multi-layer perceptron neural network. Four clustering algorithms—hierarchical, K-means, subtractive clustering, and fuzzy Cmeans clustering—were used to obtain the optimum number of clusters based on the mean silhouette coefficient and R-value before applying the fuzzy clustering algorithms. The selected models used in Iranian and Cyprus dataset were able to predict the severity of crash injuries and to estimate the response time on the traffic crash data in which the prediction accuracy was determined according to R-value, root mean square errors, mean absolute errors, and sum of square error. Based on the results obtained from Iranian data, the highest R-value and the highest amount of time were obtained for the artificial neural network around 0.87 and 7.627 seconds, respectively. The results demonstrated that the artificial neural network provided the best prediction accuracy with highest response time, while genetic algorithm had the lowest value for prediction accuracy (0.79) and response time (0.687) among the applied models. The combination of the GA and PS methods allowed for various prediction rankings ranging from linear relationships to complex equations. Based on the results obtained from Cyprus data, the highest R-value and the highest amount of time were obtained for the multi-layer perceptron around 0.89 and 2.635, respectively demonstrating that the multi-layer perceptron had a high accuracy in traffic crash prediction among the prediction models, and that it was stable even in the presence of outliers and overlapping data. Meanwhile, in comparison with other prediction models, fuzzy subtractive clustering provided the lowest value for response time (0.284 ), 9.28 times faster than the time of multi-layer perceptron. Overall, the results showed that the MLP can be the best model to predict the traffic crash severity regardless of the variables involved with crash data in which the accuracy was the important criterion. Meanwhile, more than one model can be appropriate according to the determined criteria. Considering prediction accuracy and response time could lead to developing an on-line system for processing data from detectors and/or a real-time traffic database as well as the system may be implemented in an incident management to prevent the traffic crash or secondary traffic crash in which the model can be extended through improvements based on additional data through induction procedure. Keywords: Accuracy, Classification algorithms, Prediction, Response time, Traffic crash severity. …………………………………………………………………………………………………………
Lateral Torsional Buckling of Steel I-Section Cellular Beams
ABSTRACT: Cellular beams are usually desirable in places where there are services below the ceiling and the openings allow services to pass through without increasing the floor height or building height. Architects also prefer this type of members due to their aesthetic look. After the cutting, shifting and welding of these members, there will be changes to their cross sectional slenderness since due to the heat, they experience through the cutting and welding process hence they may be subjected to different types of failure modes. In this study the lateral torsional buckling (LTB) failure mode of steel cellular beams is investigated. The LTB can cause partial failure or whole failure in the structure. An experimental steel section was verified using finite element software (Abaqus). The shell element for finite element (FE) modeling was used. FE analysis results showed a good agreement with the experimental test results. Based on the verified section, more members were modeled to study their behaviors against LTB. Some modifications were introduced to these sections in order to decrease the risks of LTB failure mode. The aim of this study, is to find ways of reducing the risks of lateral torsional buckling on perforated sections. Instead of the usual beam stiffeners, T-shaped stiffeners were used as a substitute for the beam. This kind of stiffener is a very good way of simulating the secondary to main beam connection in real life. Furthermore, the stiffener thicknesses of different values were used to see their effects on displacements. It was found that the use of T-shaped stiffeners with the increase in the thickness of stiffeners, significantly reduce the lateral displacements as well as the occurrence of lateral torsional buckling. Keywords: Finite element, Cellular beams, Lateral torsional buckling, Stiffeners. …………………………………………………………………………………………………………………………
Effects of Waste Marble and Glass Powders on Concrete Properties and Performance
Concrete, consisting primarily of cement, water and aggregates, is the most used construction material all over the world and plays an important role in the growth of infrastructure and industrial sectors. Cement manufacturing industry is one of the carbon dioxide producing sources that is caused global warming. However, using the waste materials and by-products as cement replacement materials become an attractive alternative because it helps to reduce the cost of concrete and cement manufacturing, also has numerous indirect benefits such as saving energy, reducing landfill cost and protecting the environment from possible pollution effects. Nowadays, marble dust and waste glass powders are two of the most polluting waste materials for the world environment. For this reason, in this thesis; the marble dust (MD) was examined as a partial cement replacement material with seven proportions as 0%, 10%, 20%, 30%, 40%, 50%, 60% and the glass powder (GP) was used as an additive material, 8% by cement weight, in a 0.55 water-binder ratio (w/b) concrete. Finally; experimental results indicated that MD can be used as a cement replacement material up to 10% replacement and with the use of GP both physical and mechanical properties of concrete can be improved. Keywords: Concrete, Marble dust, Glass powder, Cement replacement materials, Mechanical properties, Workability, Durability, Compressive strength, Sulphate resistance.