Dissertations for Structural Engineering (Str.E)

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A Correlation between Theoretical and Actual Column Shortening and Lateral Sway in a Vertically Asymmetric High-Rise Concrete Building
(The British University in Dubai (BUiD), 2016-11) Habrah, Alaa
The consideration of columns shortening in high-rise buildings becomes more complex and needs more attention when the building is vertically asymmetric. The inherent complexity is attributed to the dramatically unequally loaded vertical members due to mass shifting after the separation floor (the floor after which the plan is significantly reduced), which consequently leads to building rotation toward the higher side causing more lateral and vertical displacements. The gravity loads induced sway and settlement of a 360m height vertically asymmetric building in Dubai are investigated in this research. The columns and core walls elastic and time-dependent shortenings are predicted using the ACI 209R-92 model considering all the compensation measures taken, the construction method adopted, and the site conditions revealed during the construction of the tower. Sophisticated calculations including all the influencing factors of this model were performed using an Excel sheet to provide a simple interface for calculating the elastic and time-dependent columns shortening. The building was also analyzed by finite element method software, Etabs where the columns shortening and settlement were predicted using CEB-FIB 90 model for time-dependent effects which was built-in the software. The results of the two models were evaluated by comparing them to site survey readings conducted each five floors during the tower construction. It was found that both methods overestimated settlements in all floors compared to actual ones. Whilst the average overestimation of the developed Excel sheet based on the ACI 209R-92 model was 630%, Etabs analysis based on the CEB-FIB 90 model had more accurate results with average overestimation of 258%. The lateral sway induce by gravity load was predicted by the same Etabs model using two different analyses, linear and nonlinear staged construction analysis. The sway results of the two models where compared to each other to get a comprehensive overview of this behavior. Further investigation was done on a modified building model where the vertical asymmetry was removed and the building was re-analyzed by the two analyses again. The advantages and disadvantages of each analysis were provided. It was found that the linear analysis significantly overestimated the lateral sway for the original model, whereas the two analysis had close results for the modified model. The analyses results clearly evidenced that nonlinear staged construction analysis is essential to capture the real behavior of vertically asymmetric buildings.
Life Cycle Cost Analysis and Value Engineering and their Usage in the United Arab Emirates: A Case Study of Residential Buildings in Al Ain
(The British University in Dubai, 2016-12) AHMED, HEBATALLA TAHA TAHA
Anxiety of succeeding a business is uncertainty to any stakeholder. Therefore appropriate strategical planning based on financial assessment is essential, strictly speaking for long-term planning. Accordingly, life cycle cost analysis is a proper financial technique to evaluate all pertinent costs to a project during its lifetime. Whereas value engineering allows project managers to look over new designs to select the best design that fulfils performance over function. The aim of this research is to compute the life cycle cost and apply the concept of VE on residential buildings in Al Ain, UAE over life cycle of 35 years. An explanatory mixed method was followed through collecting data for new and old residential buildings in Al Ain. New buildings have less than 10 years old and was constructed using new appliances and finishes. Old buildings that have more than 10 years old and constructed poor quality and non-energy saving appliances. Old buildings’ data was collected from a survey conducted by asking property owners. After that a quick comparison between buildings in Al Ain and in the UK was conducted. LCCA was computed from cradle to grave, which includes three main phases: initial phase, operation phase and demolition phase. Initial phase contains design and construction costs. Operation phase consists of electricity, water, maintenance and replacement costs. Demolition phase includes only the cost of demolition and any associated cost. All costs were collected now except initial cost. Therefore, initial cost was uplifted to current value. Interviews were conducted to evaluate how the concept of value engineering was improved and applied efficiently at the market. Results show that initial cost for new buildings in Al Ain is more than initial cost for old buildings due to the change in requirements and regulations and the change in raw materials prices. Results found that initial cost for buildings in Al Ain and the UK are so close. In addition, initial cost is the most sensitive value to change in input. Interest rate came at the second place in the sensitivity analysis. Moreover, it has been recommended applying value engineering to save in electricity cost, the main contributor in operation cost.
Estimating Bridge Deterioration Age Using Artificial Neural Networks
(The British University in Dubai, 2017-09) AL HUSSEIN, ASEEL
Deterioration of reinforced concrete bridges is major issue in structural engineering due to the difficulty of estimating or predicting the service life of the bridge. Two types of models were developed to estimate the service life, the deterministic and probabilistic models. Nevertheless, the reliability of these models is questioned since they do not account for the many factors involved. Therefore, for this research artificial neural network is used to estimate the deterioration age for RC bridges based on deterioration data. Historical records of bridges located in London is used to train and test ANN. Feedforward neural network is designed to be able to estimate the deterioration age. ANN inputs are bridge type, member type, exposure, and defects while the target is the defects age. Since there are no standard neural network deterioration models, Design of experiment is conducted to select and monitor the most important parameters that would affect ANN performance. Learning algorithm, Number of hidden layers, number of hidden neurons and Transfer function are the four parameters selected for factorial design. Each factor has low and high-level options making 16 different combinations of neural networks. ANN analysis is run on MATLAB and Mean Square Error (MSE), regression and error histogram results are used to evaluate the performance of ANN. The results were mediocre reflecting the type of data provided in neural network training. ANN models could successfully train more than half of the data to achieve the target, However, the rest of the data were not able to achieve the desired output. Furthermore, Analysis of Variance (ANOVA) is used on MSE to determine which parameter influenced the outcome. Hidden neurons are significant factor were MSE of 10 neurons is smaller than MSE of 20 neurons, indicating a better performance for ten neurons models. Then, the deterioration scenarios are compared with ANN output age. Footbridge bridge and compression members had the longest average for service life.
REHABILITATION OF DETERIORATED REINFORCED CONCRETE MEMBERS USING ADVANCED COMPOSITE MATERIALS: A CASE STUDY OF A DETERIORATED 8-STOREY BUILDING IN THE CITY OF ABU DHABI IN THE UNITED ARAB EMIRATES
(The British University in Dubai, 2017-10) DIBSI, ANAS
The deterioration of reinforced concrete in building structures due to factors such as aging, reinforcement corrosion, humidity and oxidation, and freeze-thaw events, had imposed a great deal of stresses on these structures. In addition, unfortunate errors or omissions in preliminary designs performed by designers have motivated the researchers on finding a more durable and sustainable material that can be used in repairing and rehabilitation of deteriorated structural elements. Due to the scarcity of raw materials, the rising expenses in production, durability and ecological concerns, and the necessity to attain a high strength to weight ratio material dictated the expansion of research to discover new materials that acquire sufficient engineering properties to meet the rising demands of the construction industry. Investigations were carried out utilizing advanced polymers due to their extraordinary physical and mechanical properties that could be an ideal substitute towards the reinforcement of concrete structures. A case study presenting the practical applications and analysis for the use of advanced composite materials in the rehabilitation of deteriorated reinforced concrete structural members of an 8-storey building located in the city of Abu Dhabi were examined in this paper in comparison with the demolishing and reconstruction option of the building. The investigation undertook micro-concrete advanced composite materials as the main primary material to carryout the service life and life cycle cost analysis of the structural column elements to reach the most economical and effective solution to apply on the deteriorated structure. Although the research resulted in an extension of the service life of the structure by 9 to 12 years (± 1), the resulting repair cost for the deteriorated structural elements were determined to be higher initially by at least 11.1% with an overall lifecycle cost range between 24.7% and 32.3% higher than the re-construction cost of the said structure. While there is a great potential in terms of environmental aspects, as well as the extension of service life possibility of the structure through the utilization of advanced composites in repairing and rehabilitation of concrete structures in the GCC region, it is presently determined not as feasible and cost effective preference.
Comparison between theoretical and practical compression capacities of deep / long piles
(The British University in Dubai, 2017-11) OMAR, MOHAMED NABIL
The rate of build of high-rise buildings has accelerated rapidly, especially in the Arabian Gulf, over the last few decades, due to rapid urbanization and significant improvements in the field of the high-rise construction and technology. Many challenges were faced by the engineers in the design and construction of such buildings. One of the major challenges was the foundation systems, which are required to ensure the stability of the buildings. The common type of foundation system which is used in case of high- rise buildings is piles foundation system. In the most standards and codes of practice such as British Standard and ASTM, the piles specifications and recommendations are stated for short piles which has a maximum depth range between 18.0 to 20.0 m. Theoretical equations for pile design, charts and different soil factors and parameters are based on old studies of short piles behavior. In this research, a comparison was conducted between the theoretical pile compression capacity which is calculated from the theoretical equations and the practical pile compression capacity which is derived from the results of pile’s static load test. The study covered three different cases of bored piles constructed in U.A.E especially in Dubai. The piles used in this research have a depth ranging from 30.0 to 65.0 m. This type of piles is classified in this research as long or deep piles. A finite element model of each pile was modeled by using PLAXIS 2D software, to compare the practical and theoretical piles capacities. It was found that the theoretical compression pile capacity is 60 to 70% of the practical pile capacity with the same specifications (pile diameter and pile depth). As a conclusion of the results, the theoretical equations which are used to calculate the pile compression capacity can be improved to give results very near from the practical condition.
Analyzing the structural cost, performance, and flexibility in the terminal design of Mumbai Airport
(The British University in Dubai, 2018-09) ZAMA, SYED MUDASSIR US
The recent growth in the aviation industry has led to the highest necessity for the development in designing the airports. Statistics are available for a few airports, but there is no comprehensive base of information on how airport terminal buildings operate or the conditions their user experience. The major aim of this research is to design a framework for analyzing the performance, cost and flexibility in terminal design of airports; to do so the main studies has been done exploring factors affecting the management and functionality of airport terminals considering the different parameters and the effectiveness of the terminal and the key challenges in designing functional aspects of an efficient airport terminal. The contribution of this research work will help approach to develop an efficient framework to overcome the problems occurring in airport terminals. The research paradigm will be positivism, carried out scientifically in order to analyze the performance and flexibility of the airport terminal. SPSS software has been used for the descriptive and regression data analysis for interpretation; the analysis presents an elaborate picture of the findings; other statistic tools are also used. The conclusions are based on the analysis of data presented, suggestions are made for, and that can be analyzed, in coherence with the research objectives further if any. Hence, posit certain areas of research that can be further extended and broadened by other researchers in near future.
Seismic Retrofitting of Reinforced Concrete Structures
(The British University in Dubai, 2018-10) KANDY, ARCHANA THUNDY
In the current scenario of ever-increasing incidence of earthquakes around the world, we need to carry out a macro level study and review the causes of earthquakes and consequential effects of it and identification at Source and tracking it to the Society. Natural calamities cause severe and more often than not, indescribable suffering, loss of lives and livelihood, destruction of houses, properties, infrastructural installations and facilities, separation of humans and great many other losses. Thus the implications are multifaceted involving economic hardships, human sufferings and a great deal of severely adverse social effects. For ascertaining the structure responsiveness and resistance to earthquakes, the source/ path parameters and site features need to be studied and depicted scientifically to assess the geophysical as well as seismological effects. The buildings which were designed and constructed according to the old codes may not satisfy the requirements of the presently used seismic codes and design practices. Therefore, it is crucial to reassess the codes to prevent economic loss and loss to human life and property caused during earthquakes. Buildings damaged in the past earthquakes or the existing buildings deficient to resist seismic forces need to be retrofitted for better performance in future earthquakes. Seismic evaluation is the first step before retrofitting procedures to determine the most exposed and vulnerable members and deficiencies in a structure in order to protect them during an event of an unexpected earthquake. The seismic retrofit/rehabilitation procedure intents to enhance seismic performance of the structure and rectify the insufficiencies by enhancing stiffness, strength or deformation capacity and also improves connections. The present study deals with the seismic retrofitting of two structures located in diverse seismic zones. Each structure is retrofitted under two different schemes and the results are compared to find out a better method of retrofitting for both structures. After the analysis, the results were compared under time periods, base shear, and modal participating mass ratios, bending moments and shear forces for all beams and moment capacities and axial forces for all columns and were found satisfactory to withstand the design earthquake forces and results are tabulated in the report.
Comparison between the American code ASCE7-16 and the Australian code AS1170.4 against the seismic design effects
(The British University in Dubai, 2018-11) AL-OBAIDI, ALI
Engineering is a professional art of applying science to the efficient conversion of natural resources for the benefit of man. Engineering, therefore, requires above all creative imagination to the innovative, useful application for natural phenomenon.” (International Journal of Engineering Research & Technology (IJERT), Vol. 3 Issue 3, March – 2014). This work implemented to compare two codes, American and Australian by designing a sixty -floors building using reinforced concrete structure from the economic point of view. Two critical structural codes adopted, ASCE-7 16 and AS1170. These codes compared in term of strength design necessities of structure elements and the shear design included as well. During this study, calibration and elaboration of the models adopted along with the criteria consecration revealed. Though the main principles are the same and the seismic zone will moderate, the details were different and made the comparison accurately, the analysis implemented via ETABs software from CSI Company established in the USA. This work will show the development of the Australian code especially for the earthquake loading using the AS1170.4, 2007. The Australian engineers established new response spectrum design contains a better illustration of the acceleration, displacement and velocity for the type of site soil (soft and rock). The used procedure to establish the spectrum could use in another country which has a low/ moderate seismicity. The AS1170.4 used a tiered approach for the earthquake load starting from simple force to complicated displacement method. One of the significant advantages of this method especially on the low seismic zone is given the engineers to design against the vertical and wind loads then perform the displacement checking for the earthquake impact. In parallel, the ASCE-7 16 deliver the all the possible design requirements for general structures along with the dead, live, snow, flood, rain, soil, wind load, and atmospheric ice with the proper combinations which is fit for the building code. The standard is a revision of ASCE-7 10 which is a revision of ASCE-7 5 respectively and it's providing a full update and re-arranged of the wind load. Also, it has a new ultimate wind load maps along with the reduced load factors and it has an update on the risk targeted seismic maps. This standard is a comprehensive and important version as a part of the building codes which are used in the United States.
Critical Review of Reinforced Concrete Design Codes and Their Relevance to the United Arab Emirates
(The British University in Dubai (BUiD), 2018-11) GOWRISHANKAR, PRATHIBHA
The United Arab Emirates, is a home to structural engineers from different nations who hold expertise in their regional building concrete design codes. Since the 1980’s and 1990’s The British Standard (BS 8110) and the American Standards (ACI 318) have been of significance and widely used within the Municipalities in UAE. To maintain a uniformity and consistency in design and analysis of structures, it is required to critically review design codes to closely examine the similarities and differences among code provisions. This could help structural engineers to switch between codes. Hence, an attempt is made to carry out a general and parametric comparison of some international design codes followed by a three-tier critical review of ACI 318-14 and BS 8110-97 considering the fact that these codes are widely used within UAE. The three-tier comparison involves examining the results of literature review, theoretical investigation and practical design of frame elements of a G+40 story building using ETABS software. The results were compared in terms of dead and live loads and their combination, flexural and shear capacity of beams, columns and slabs, deflection and minimum and maximum amounts of longitudinal and transverse reinforcement, to arrive at a more economical solution without compromising strength and stability requirements. The results of the three-tier critical review showed that designs conforming to British Standards are preferred over the ACI Standards owing to their adaptability to the construction industry and environment in UAE which contributes the best possible solution.
Critical Review of Steel Column Base Plate Design Codes and Their Relevance to United Arab Emirates
(The British University in Dubai, 2019-05) SREENIVASAN, SREEJU
Structural engineers are often posed with a question for an economical design of a structural building which would decide the overall economic and the time concern in a construction. If the design is at optimum by choosing a suitable code the involvement of the materials would be less which will help to decrease the pollution caused in the environment as well. In short where structural steel works are being used with other structural materials the importance of various connection plays to be indispensable. One of which the steel column base plate connection that would perform adequately for the specified demand. This is the most critical element in the entire structure which would carry the load of the entire building through the columns to transfer to the base plate and then to the ground and ensuring the stability of the structure. Hence this dissertation intends to bring about a requirement of workability such as the easy and efficient construction, working the connection with high loads and deformation with sufficient capacity ensuring least cost, maintenance and with long durability with an economical design code. In the United Arab Emirates where the country is home to all the high rise structures will need this aspect as the cost involved is at high steak. The three codes which are thus reviewed in this are the Eurocode, American and the British standard codes emphasizing more on latter two codes (British and American). The involvement of the computer analysis supporting the work will provide much understanding to choose which code is more suitable for a desired project for the municipalities and consultancies in U.A.E.
The Impact of Using Specialist Geotechnical Software in Modeling of Pile Raft Foundation (PRF)
(The British University in Dubai (BUiD), 2019-07) SHOKR, MOHAMED
Due to rapid urbanization, the construction of tall towers has become common in all the metro cities. The column loads from the towers will be very high depending on the height of the tower and they require very efficient foundation system to carry them. It is very common these days that most of the towers are founded on Piled raft foundation systems. Reinforced concrete slabs of uniform thickness acting as shallow foundations, covering complete plinth area of building are called as Raft foundations. Raft foundations help in distributing the loads from the wall or columns to the lower soil layers effectively. Piled Raft foundation (PRF) is formed by addition of piles to a Raft Foundation and it increases the load bearing capacity. Horizontal loads can be resisted to a maximum extent due to the addition of piles to a raft foundation. Reduction of settlements, both maximum and differential and enhancing the ultimate load capacity will improve the performance of the foundation to a greater extent. Various software’s are available to analyze the piled raft foundations under various loading conditions, for providing the optimum design. Piled raft foundations are analyzed using CSI SAFE by most of the structural engineers. Since the Raft Foundations will be supported directly on soil, structural software like CSI SAFE do not simulate the exact site conditions, since they model the soil only as springs. Hence a sophisticated geotechnical software PLAXIS 3D is used to analyze the results of Piled raft foundation for a case study and the results are compared with the results from the other software. Plaxis 3D have got various constitutive models to simulate the exact ground conditions and simulates the soil structure interaction between the raft, piles and soil more effectively. A case study of one of the towers in Abu Dhabi is considered to check the comparison between two software initially. Later, a typical piled raft foundation is considered based on the typical details of first case study. This dissertation includes the detailed procedure regarding modelling the piled raft for the second case study using both the software, comparison of results and discusses the advantages and disadvantages of both the software in case of geotechnical applications.
ANALYSIS OF COMPOSITE ACTION OF PRECAST HOLLOW CORE SLABS AND CAST IN PLACE MESH REINFORCED CONCRETE TOPPING
(The British University in Dubai (BUiD), 2019-09) Omer, Sajjad
Considering composite action of hollow core slab with cast in place mesh reinforced concrete topping helps to provide longer hollow core slabs and reduces the overall weight of the structure. Research has shown that composite action normally can be attained through studs or other connecting elements from the bottom element but for hollow core slabs the roughness of the top surface is enough to attain the composite action. This study aims to analyze the composite action of hollow core slabs made of ELEMATIC sections with thicknesses 150mm and 265mm with cast in place mesh reinforced topping. The thickness of topping was considered as 65mm for 150mm thick hollow core slab and 70mm for 265mm thick hollow core slabs. A load test setup was made for both 150mm thick hollow core slab and 265mm thick hollow core slab which mirrored the actual site condition. The connecting reinforcements were provided as per normal practice and the supports were considered as simply supported after which the topping was setup with the wire mesh and the concrete poured. Readings from the three gauges below the hollow core slabs were recorded at 0% loading, 25% loading, 50% loading, 75% loading, 100% loading, 100% sustained loading and 0% released load condition after 24 hours. For 150mm thick hollow core slabs, 0.29mm was the deflection for 100% sustained loading and for 265mm thick hollow core slabs, 3.36mm was the deflection for 100% sustained loading. These two values are way less than the actual estimated values. The results indicate that composite actions are valid for uncracked hollow core slab sections considered in the tests. Further investigations can confirm the composite action for other hollow core slab sections and also for section which are cracked
ADAPTATION OF BIM WORKFLOW IN STRUCTURAL ENGINEERING PROJECTS & THE NEED TO ESTABLISH A NATIONAL BIM STANDARD
(The British University in Dubai (BUiD), 2020-02) Thomas Thampy, Tony
The Introduction of the concept of BIM into the construction industry, have made significant changes to the working standards and workflow pattern. This thesis examines the said changes in comparison to the traditional working methods in all phases of project starting from pre-concept to demolition with respect to the structural engineering discipline. Case studies are done to check the typical workflow in a BIM environment for structural design. Thus analysing the skills required and deliverables that are to be produced in BIM working environment for optimum workflow. The BIM implementation strategies and the rate of BIM adaptation in 5 selected countries including UAE are analysed. The relation between national BIM standards and the rate of BIM implementation in the respective countries are also evaluated. The current BIM awareness in the UAE is also analysed by a market survey conducted among industry experts in the UAE, focusing on the obstacles for the implementation of a national BIM strategy. The adaptation of the BIM into the structural engineering workflow has shown many improvements in comparison to the traditional workflow such as software interoperability, ease of production of schedules and drawings, 3D representation of reinforcement and other technical data, etc. National mandates and standards in relation to BIM have shown to increase the rate of BIM adaption in respective countries and also achieve a sense of regularity in the construction industry and authority standards. From the market survey conducted, the professionals have expressed the need for similar BIM standardisation in the UAE and also the current obstacles for the same.
THERMAL EFFECTS OF UNDERGROUND CARPARK STRUCTURE A COMPARATIVE STUDY OF UNDERGROUND CAR PARK CONCRETE BUILDINGS IN DUBAI - UNITED ARAB EMIRATES
(The British University in Dubai (BUiD), 2020-02) Omar, Ola
The underground car park buildings considered as an ideal solution for the parking spaces in urban area, and it is more commonly used when the land values are high. So, the main intention to have a durable and economical building along it service life. Particularly these types of buildings are vulnerable to the structural distress related to the restrained volumetric change due to the shrinkage and thermal change during the parking operation, many of the designers and owners avert to have a separation in the underground structure, especially when the water table is very high. But Ignoring the thermal effects with the structure stiffness characteristic can lead to premature deterioration and cracking because of the generated forces. This study intent to show the importance of thermal analysis of underground car park concrete building, by conduct a comparative study between three models of three floors underground car park building, with length around 147 m and width around 38 m. The first model analyzed the building for the gravity load only, and the second model analyzed the building for gravity load and thermal change in absence of expansion joints, while the third model analyzed for the gravity load and thermal change in present of expansion joints. The analysis of the three models shows how the thermal change of underground parking structure affect members internal forces with unexpected amount, which at some extend are not considered in the design by most of the designers. The forces produced from the strain forces (thermal changes) must be well studied as it is different than the forces produced from the gravity loads, generally these forces affect the connection design, specially between the walls and slabs or columns and slabs, and how this effect is reduced by the presence of expansion joints. The comparisons between the three models covered the comparisons of structural elements forces (columns, Slabs and the walls), in addition to the comparison of the whole building maximum drifts and maximum displacements, and the columns shear forces which produced specially on the columns in both directions due to the horizontal movements of the slabs due to the thermal changes. These forces and results record in a manifest the maximum in the model analyzed for thermal stresses with full building length (without expansion joints), while the presence of the expansion joint results in structure with less slab stresses, wall stresses, building drift and displacement, member forces which in-turn lesser section properties and reinforcement hence leading to economical design of the structure.
The behavior of Tapered High Strength Concrete Filled Steel Tube (CFST) Column connected to Encased Steel Reinforced Concrete Composite (SRC) Column
(The British University in Dubai (BUiD), 2020-06) Abdelhamid Azzazy, Yasser
The use of Convectional Concrete Column is often limited in high-rise Buildings due to the constraint from the architects on increasing size of the columns, so the composite columns provide appropriate solution to satisfy the architect and the Client with smaller column size. Nowadays, Composite Columns have been widely developed in the construction of the high-rise buildings, long span structures, and bridges. Composite columns have two main types, encased composite columns (SRC) and concrete filled steel tube columns (CFST). This research is focusing on the behavior of a tapered concrete filled steel tube column (CFST) connected to encased composite column (SRC). The purpose of having two different sections along the column height is to enhance the flexure resistance of the column at the top edge by introducing CFST element, while the lower part is modeled as SRC element and it is mainly subjected to axial compression with significant reduction in bending moments compared to the top part of the column. The behavior of the tapered CFST column connected to SRC column has been studied using two main different parameters. The first parameter is the type of loading, such as pure axial compression, axial compression and uni-axial bending, and axial compression and bi-axial bending. The second parameter is the concrete strength, with different concrete strengths ranging from C40MPa to C70MPa. Both parameters have been carefully considered in the analysis of the composite column. The steel section used in the research design model has a yield strength of 355MPa. The steel reinforcement used in the model has a yield strength of 500MPa. The column has been modeled using 3D-Fiber (Solid) Finite Element Method. The cross sectional of the columns has been divided into tiny fiber (solid) elements. The advantage of using a fiber (solid) element is easy to assign the tiny element as concrete or steel, even stiffeners plates have been modeled by adopting the fiber element methodology. The maximum size of the fiber (solid) element is (10mm x 10mm) which warrant more accurate results in terms of stress and strain. The vertical rebar was ignored from the 3D Fiber Model. The stresses and strains extracted from the 3D-FE models have been compared to the simplified formulas adopted by EUROCODE-4 and American Standards AISC / ANCI . The research illustrates the load path and stress / strain distribution through different structural elements connected to each other under deferent type of loading. The results demonstrate that the 3D-FEM displays some differences in the composite section capacity under different type of loading compared to the simplified formula adopted by Eurocode and AISC/ANCI. The stress and strain distribution demonstrate a smooth transition between CFST element and SRC element with local stress concertation on the concrete and steel at the interface between CFST element and SRC element. The concentration in the stresses is not considered in the simplified formula by the standards codes, so it should be carefully considered in the section capacity.
The Influence of the Alkaline Activator on the Life Cycle Assessment of Alkaline Activated Natural Pozzolan Geopolymers Concrete
(The British University in Dubai (BUiD), 2020-07) Kamil, Marwah
This paper studies the effectiveness of replacing cement in concrete with natural pozzolan, originated from Saudi Arabia, on the reduction of the harmful gasses, carbon dioxide equivalent gases, during the production process of the concrete. Life cycle assessment is done on the alkaline activated natural pozzolan geopolymer concrete, global warming potential of 100 years GWP100 category. The life cycle assessment exercise was also done on alkaline activated natural pozzolan geopolymers where the natural pozzolan was activated with different types of alkaline activator to reduce the GWP100 of the geopolymer concrete even further. The results of the study showed that the geopolymer with natural pozzolan activated by sodium hydroxide and sodium silicate have the lowest GWP100 of 106 kg.𝐶𝑂􀬶.eq, which is lower than that of the PC concrete by 72%. Also, it is found that the alkaline activator is responsible for the largest amount of the carbon dioxide equivalent gases produced during the production of 1 𝑚􀬷 of the geopolymer concrete. Two further life cycle assessment exercises were done to replace the sodium silicate alkaline activator with sodium hydroxide and silica extracted from rice husk ash. The results of the life cycle assessment, GWP100 category, showed that both geopolymer concretes have higher GWP100 than that of the natural pozzolan activated with sodium hydroxide and sodium silicate. The GWP100 of the natural pozzolan alkaline activated by sodium hydroxide geopolymer and natural pozzolan activated by sodium hydroxide and silica extracted from rice husk ash are 114 kg.𝐶𝑂􀬶.eq and 197 kg.𝐶𝑂􀬶.eq respectively. However, all of the alkaline activated natural pozzolan geopolymer concrete showed GWP100 less than that of the PC concrete by at least 48%. The results of the life assessment exercise are then compared to life cycle assessment exercises done by other researchers on alkaline activated natural pozzolan geopolymer concrete as well as other types of geopolymer concretes. The recommendations of this study is that further research needs to be conducted to study the properties of the alkaline activated natural pozzolan geopolymer concrete and further life cycle assessments need to be conducted on different mix design option on both raw and calcinated natural pozzolan to encourage the consultants and contractors to replace cement with more sustainable and durable material like the natural pozzolan.
Structural use of composite materials
(The British University in Dubai (BUiD), 2020-10) Alansari, Ali
The construction world is changing daily. Research on new materials that can be used to replace traditional ones has been aggressive. The fibre-reinforced polymer is one of the new technologies that has been adopted in the market. Fibre-reinforced polymers are composed of more than two materials bonded together. FRPs have widely been used in the industry, such as bridge construction, counterparts, buildings construction and among other vital uses. FRP materials have superior properties that make them more pronounced in the field of construction. Some of the known advantages that make these materials quite important include strong bonding. The most important advantage of fibre composite material is the fact that they have high strength properties. There are various types of FRP materials; the type variety is dependent on the arrangement of the fibres. The direction of bonding includes multidirectional, bidirectional, random mat, and woven type. The most important one is the multidirectional one that offers high strength. This research aims to conduct extensive research on the application and the usage of FRP material in the construction industry. Among the methods that have been exploited in this study include pultrusion, which is the most popular process used in the industry. The materials used in the manufacturing process include reinforcing fibres and fibre fabrics. Fibre composite materials have several advantages and disadvantages. However, the advantages are the most exploited part, which is why they have been adopted in the industry. Various case studies have been explored in the research to verify how much the FRP has been used globally. One of the cases is the use of GFRP in Netherlands. The case study that has been considered in this research is the 22 m bridge that was constructed in Bronlibelle. The bridge was built using GRPR, and various standards were used in the design process. The measures that were used for this case include CUR96, EN991, and EN990. Among the details that have been discussed in this study is the contractor and the challenges they met while constructing the bridge. Other composite materials such as Carbon Fibre Reinforced Polymers (CFRP) have been discussed in detail. The details given light in this study include composition, uses, and advantages that these materials can have compared to others used in the construction industry. The research has established that most of the advantages and disadvantages are the same for fibre material. The research used secondary sources of data that have already been done elsewhere to develop the final judgment. The research shall use case studies that have already been done. To use the material for construction, it is essential to consider the economic part of it. In this study, the economy involved when using this material has been discussed. This research established that the FRP materials are among the best since they are economical. The research demonstrated that carbon fibre cost is lower as long as production is high. Among the costs that have so far been discussed in this study include material cost, process material cost, the energy needed for the production process, labor cost, capital, and other costs. Therefore, the research shall help the reader with alternative construction materials.
Horizontal Shear Strength at the Interface of the Concrete Beams Cast in Two Time Stages
(The British University in Dubai (BUiD), 2020-12) Abushaaban, Hatem Ady
Composite concrete is a method of construction that uses both precast and cast in situ concrete to produce a structural element. In framing big slabs areas, the use of precast slabs and beams is being an economical way of construction. The best procedure is to employ beams of inverted T section, which bottom flange will act as a ledge to seat the precast slab. Topping concrete slab is then cast on top of the precast slabs and beams. It is cleaner and safer than the full cast in place construction. This kind of construction which is cast in two stages at different times reduces the quantities of formworks at site and reduces the back propping which in some cases is required to be extended below to multiple levels according to the expected construction loading. Accordingly, more clear spaces for lower levels will be available so that other site activities can be accomplished to complete the job faster with less building materials and reduced risk levels. The bond strength between the precast concrete part and the cast in place part is essential to provide the monolithic behavior for the composite concrete members. The integrated monolithic behavior is achieved only if all forces including the horizontal shear are fully transferred at the interface. From the structural normal practice, the word “interface” means the plane between two different materials; such as concrete to steel or concrete to concrete that is cast in stages at different ages. This interface which is studied in this dissertation is that the plane between the precast and the cast in situ parts of the composite concrete beams. The rough surface of the precast beam part, aggregate interlock, concrete strength and the steel bars crossing the interface between the cast in place and precast parts are the main factors that affect the horizontal shear strength of the that interface. The international design codes propose semi empirical equations to determine the horizontal shear strength considering adhesion, friction caused by normal stress and friction caused by interface steel rebar clamping stress. Usually the experimental tests are done on series of specimens of small size and in some other cases, are done on small sized composite beams of short span that can be accommodated in a concrete testing facility. The small specimens testing somehow reduced the level of reliability of the results. Accordingly, there is a considerable difference in the proposed interface shear strength limits between the different structural design codes. This dissertation presents a study of four composite beams with different sections, properties and reinforcement that were experimented for shear friction in a previous research. The beams are modeled using a 3D finite element software. A shear friction design hand calculation is provided as well using the provisions and equations proposed by the code of practice. The dissertation provides a comparison between simplified code approach, 3D finite element model and results from the experimental work published by Anil Patnaik at 1992.
Seismic strengthening of Reinforced Concrete Structures using External Lateral Post Tensioning
(The British University in Dubai (BUiD), 2021-04) Murugesan, Usha
The constructions of buildings before the 1970s where not in coherence with the seismic design or any type of seismic codes hence the buildings have to be investigated and do the necessary strengthening to withstand the seismic effect. Those vulnerabilities of structures which has added forth and raised cognizance for seismic Strengthening needs. Design codes now consist of seismic provisions, and those buildings which are constructed in the future are earthquake-resistant structures. Surveys after earthquakes have been analysed to interpret the collapsed structures to study and learn the possible failure causes and mechanisms. The most destructive natural hazards is earthquake. A seismic event may cause a huge loss of property as well as life. It is estimated that around 10000 people are killed every year due to calamity. This, in turn, results in a huge annual economic loss. Hence the construction industry takes critical steps to prevent and avoid the collapse as well as reduce damages caused to the structures. The method of externally applied post tensioning of tendons (EPT) is a powerful method of strengthening and repair of structure which are in existence. The technique of EPT can be used in all types of framing i.e.; to concrete buildings, structural steel buildings and wood structures. It’s a unique method of strengthening in which the strength of an existing structure is increased for its stability and also reduces the deflection in an existing structure which have been through an earthquake damage.
Comparison of the Provisions of ACI318-19 Code and Eurocode on the Structural Design and Cost Analysis, of a High-rise Concrete Building Subjected to Seismic & Wind Forces
(The British University in Dubai (BUiD), 2021-05) Oussadou, Samy Elhadi
This work aims to compare two codes; ACI 318-19 and Eurocode in terms of lateral effect on high-rise building, focusing on the seismic and wind provisions, and since these two forces effect the structural elements geometry, thus the cost comparison was included, by comparing the amount of reinforcement used. Since both of the codes have different standards and factors, therefor it is expected that there will be some differences in the structural design. This research contain design and analyses of a high-rise building consisting of 50 storeys reinforced concrete structure and comparison of several provisions. This research study investigates the difference between seismic and wind results between the two codes and if there might be any differences in the structural elements reinforcement amount, which will affect the cost of the building.

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