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Master of Science / Department of Civil Engineering / Asad Esmaeily / Performance-based building design is a necessity in geographic locations where buildings are susceptible to large earthquakes and high winds. This design method requires an analysis of the performance of the structural system with loadings and deflections caused by earthquakes and wind. Current design codes include the load intensity in analysis procedures, but do not consider the effect of load pattern in the performance analysis of reinforced concrete columns. Because a thorough analysis must take into consideration load pattern and load intensity, computer software is ideal to analyze these systems. A computer program was originally developed by Esmaeily (USC_RC), and was revised later to be renamed (KSU_RC) in order to make the analysis of concrete column performance accurate, yet simple for design purposes. This analytical tool used analytical methods and material models, verified against experimental data, to accurately predict the performance of reinforced concrete columns under various loading conditions, including any pattern in lateral direction and independently variable axial load. However, the program was limited to circular, rectangular, hollow circular and rectangular sections and uniaxial lateral curvature and displacement. The next generation of the program, KSU RC 2.0, was developed to overcome the aforesaid limitations.

Consideration of the reinforced concrete beam as a composite beam with incomplete interaction, the effect of principal strains in the shear span is studied. The influence of bond slip on the formation of cracks is studied both analytically and experimentally. / Thesis / Master of Engineering (ME)

Concrete is a versatile building material used all over the world. Today's constructions in building and civil engineering have high requirements and complexity that require a carefully executed dimensioning in connection with planning. Calculation programs that work based on standards are a tool for designers in calculation work. Complicated programs or ambiguities in the programs can take up important time, therefore good and clear programs are necessary for time efficiency. This thesis has compared the calculation programs Concrete Beam and Beam EC2, which both are calculation programs used for dimensioning concrete beams. Concrete Beam is used by most constructors in Sweden, while Beam EC2 is a new calculation program that is not used to the same extent. There is therefore a need to evaluate the respective calculation programs in order to increase knowledge in the construction industry about the differences between the calculation programs, as well as to open up the possibility of using more calculation programs in the future. The aim of the thesis is to investigate whether there are differences between Concrete Beam and Beam EC2 when dimensioning a concrete beam. To implement this, the differences in factors such as ease of use, available functions and a calculation result are examined. A smaller sensitivity analysis is also performed to analyze the stability of the calculation programs' values.    The thesis is carried out as a case study with input from a completed reference project by Sweco Sverige AB. The reference project contributes realistic values ​​that are used as input data in the study. The values ​​from the reference project are supplemented with smaller hand calculations for the loads acting on the beam, for example the dead weight and the wind load. This is because values ​​from the reference project are missing. The implementation involves applying the specified values ​​for the inputs from the case study and the hand calculations in the programs. The result shows how each program considers whether the concrete beam can withstand failure and the serviceability limit state, but also how the programs chose to dimension reinforcement in the beam, as well as the result from the sensitivity analysis. Based on the results, a certain difference in the calculation programs could be established, for example how they chose to shape the reinforcement in the beam, which then also led to differences in crack width and deformations. In contrast, the results for the moment and shear force were almost identical. The study also included a sensitivity analysis where Beam EC2 showed stable values ​​while Concrete Beam got a more uncertain result. Based on the results and the sensitivity analysis, the conclusion is that there are clear differences between the calculation programs. The usability is discussed in the opinion of the authors but needs further studies to be used as a general conclusion. The result is limited according to boundaries and the time frame for the work, but there is an opportunity for further studies regarding the differences and usability of the programs in the industry.

An experimental program was conducted to investigate the strength and deformations of deep beams reinforced with Carbon Fibre Reinforced Polymer (CFRP) longitudinal and transverse reinforcement. Two groups of beams were tested, with each group comprising three beams. Two of the three beams in each group were reinforced with CFRP bars while the third beam was reinforced with conventional rebars and the latter beam was used as a control specimen. Beams in group 1 had span-to-depth ratio of one, while those in group 2 had a span-to-depth ratio of two. Beams in both groups had height of 900 mm and width of 250 mm. All the beams were simply supported and were tested in four-point bending with the point loads applied at one-third of the span. The test results revealed no significant difference between the behavior of the FRP reinforced beams and the companion control beams. On the other hand due to lack of hooks at the ends of the CFRP bars, and the loss of bond between the CFRP fibres and the sand grains on the surface of the bar, the failure in the CFRP reinforced beams was caused by the loss of anchorage while in the steel reinforced beams, the failure was initiated by the yielding of the longitudinal steel, followed by the crushing of the horizontal compression strut, but the nodal zones did not fail in any of the beams. Consequently, it was concluded that CFRP reinforced deep beams could be designed using the current CSA method for conventional steel reinforced concrete deep beams, provided the anchorage or bond strength of FRP bars could be properly determined. The existing nodal efficiency factors for the CCC nodal zones, as given in the CSA A23.3. standard, could be applied to CFRP reinforced beams while the corresponding factor for the CCT zone may be conservatively assumed to be 0.68. Finally, despite the linear elastic behavior of CFRP reinforcement, deep beams reinforced with CFRP bars could be designed using strut and tie models. / Thesis / Master of Applied Science (MASc)

This thesis presents the results of a numerical investigation of the whole range, large deflection behaviour of axially and rotationally restrained RC beams and interactions between beams and columns in RC frame structures exposed to fire. The dynamic explicit time integration algorithm implemented in the general finite element package ABAQUS/Explicit solver was used so as to overcome various modelling challenges including temporary instability, local failure of materials, non-convergence and long simulation time. Either load factoring or mass scaling may be used to speed up the simulation process. Validity of the proposed simulation model was checked by comparison of simulation results against relevant test results of restrained RC beams at ambient temperature and in fire. The validated ABAQUS/Explicit model was then used to conduct a comprehensive study of the effects of different levels of axial and rotational restraints on the whole range behaviour of RC beams in fire, including combined bending and compression due to restrained thermal expansion, bending failure, transition from compression to tension when catenary action develops and complete fracture of reinforcement at ultimate failure. The numerical results show that different bending failure modes (middle span sagging failure, end hogging failure due to fracture of tensile reinforcement, end hogging failure due to concrete crushing) can occur under different levels of boundary restraints. Furthermore, release of a large amount of energy during the rapid transition phase from compression to tension in a beam prevents formation of a three hinge mechanism in the beam under bending. The numerical results have also revealed that reliable catenary action develops at large deflections following bending failure only if bending failure is governed by compressive failure of concrete at the end supports whereby a continuous tension path in the beam can develop in the top reinforcement. To allow fire engineering practice to take into consideration the complex restrained RC beam behaviour in fire, a simplified calculation method has been developed and validated against the numerical simulation results. The proposed method is based on sectional analysis and meets the requirements of strain compatibility and force equilibrium. The validation study results have shown that the simplified method can satisfactorily predict the various key quantities of restrained beam axial force and beam deflection-fire exposure time relationships, with the simplified method generally giving results on the safe side. The validated explicit finite element model in ABAQUS was also used to investigate structural interactions between beams and columns within an RC frame structure with different fire exposure scenarios. When fire exposure involves beams and columns located in edge bays of a frame, catenary action cannot develop. Also due to thermal expansion of the connected beam, additional bending moments can generate in the columns. Furthermore, very large hogging moments can be induced at the beam end connected to the internal bay. It is necessary to include these bending moments when designing beams and columns under such fire conditions. Catenary action can develop in interior beams of the frame when fire exposure is in interior bays where the beams have high degrees of axial restraint.