The first objective of this study was to develop an updated version of FormWorks, FormWorks 3.5, which is more user-friendly and compatible with newer versions of VecTor2. The second objective was to create a new version of FormWorks, FormWorks-Plus, capable of modeling different types of structures including 2D Membrane Structures, 3D Solid Structures, Shell Structures, Plane Frame Structures, and Axisymmetric Solid Structures.
FormWorks 3.5 was mainly developed to model the different types of materials now available in VecTor2 including Reinforced Concrete, Structural Steel, Masonry, Wood, Concrete-Steel Laminate, Concrete-SFRC Laminate, Masonry-SFRC Laminate, Concrete-Ortho Laminate, Reinforcement, and Bond. In addition, the Job Page was updated with the most recent behavioural models and analysis parameters. The zooming feature of FormWorks was improved to display the geometry of the finite element model properly. A new load type, Nodal Thermal Load, was added to the program allowing the user to define thermal loads for nodes. The performance of the truss and rectangular elements was improved. Finally, updated dialog boxes for nodes, elements, restraints, and load types were added to facilitate the modifying process of finite element model. FormWorks-Plus is a new version of FormWorks, compatible with entire suite of VecTor programs. In addition to the XY, XZ, and ZY plane views, sectional and projection views were added to the program, greatly contributing to its utility. FormWorks-Plus also uses a supporting program called 3D View which is written with the MFC library and OpenGL (Open Graphics Library), allowing the user to see a 3D view of the structural model. In addition, four different types of node coordinate definitions, five types of elements, several load types, and new material properties are added to the software, making it compatible with the remaining VecTor programs. The complete details of the research program can be viewed in Sadeghian (2012).
A research program was conducted which focused on improving the ability to model the cracking behaviour of steel fibre reinforced concrete members containing conventional deformed steel reinforcing bars. The objective of this experimental program was to observe the changes in crack widths and spacings caused by the inclusion of steel fibres, as well as to observe the effect of steel fibres on the tensile stress-strain response of reinforced concrete.
The uniaxial tension test specimens had the following dimensions. The specimens were one metre in length, with 250 mm of reinforcing bar protruding from each end for gripping in the testing machine. The square concrete cross section was varied from 50 mm x 50 mm to 200 mm x 200 mm, and the reinforcing bar size was varied from 10M to 30M (Canadian bar sizes). The steel fibre types and volume contents were also varied. Dramix RC-80/30-BP (high-strength 30mm fibres, l/d~80) were used primarily, but the effect of using RL-45/50-BN (normal-strength 50mm fibres, l/d~45) and ZP 305 (normal-strength 30mm fibres, l/d~55) were also investigated. A duplicate of each specimen was produced and tested in order to minimize statistical variance. A total of 60 uniaxial tension tests were performed. It was observed that crack widths and spacings decreased with increasing fibre content, increasing fibre aspect ratio, increasing conventional reinforcement ratio, and decreasing conventional reinforcing bar diameter. These observations were developed into a stabilized mean crack spacing model which accounts for the influence of steel fibres on cracking behaviour. This model was based on the CEB-FIP 1978 Model Code formulation. This new analytical cracking behaviour model was found to predict stabilized crack spacings with far greater accuracy than those currently available in the literature. The complete details of the research program can be viewed in Deluce (2011).
Extensive work was conducted to investigate the effectiveness of hooked-end steel fibres to control cracks. Seven types of material tests were performed: uniaxial tension test, cylinder compression test, modulus of rupture test, splitting test, free and autogenous shrinkage test, and restrained shrinkage test. In addition, ten 890×890×70 mm concrete panels were tested under in-plane pure-shear loading using the Panel Element Tester. The parameters of study were the fibre volume content (0.5%, 1.0%, and 1.5%), the concrete compressive strength (50 and 80 MPa), and the fibre geometry and tensile strength. In addition to the experimental study, a model was developed to investigate the behaviour of a 1D restrained FRC member subjected to shrinkage.
The experimental results indicated that the addition of fibres significantly improved the behaviour of the concrete, particularly the crack control characteristics, the post-peak compressive response, the post-cracking tensile response, the toughness, and the ductility of the concrete. The results also indicated that steel fibres were as effective as conventional reinforcement in controlling shrinkage cracking, provided that sufficient fibre volume content was added to the concrete. For example, in order to achieve a maximum crack width of 0.35 mm, a minimum fibre content of 0.9% and 1.1% should be provided for 50 MPa FRC containing high aspect ratio fibres and low aspect ratio fibres, respectively. In addition, the results indicated the importance of fibre content and fibre aspect ratio on the effectiveness of fibre reinforcement.
Although modern design codes typically require concrete frame structures to be designed to be ductile and flexure-critical in their behaviour, many situations arise in practice where shear-related mechanisms play a significant role in the response of structures. Advanced analytical tools that rigorously consider shear behaviour are required for a comprehensive and accurate assessment of the performance of such frames. However, the typical analysis tools currently available either ignore shear mechanisms altogether, employ opaque and overly-simplistic formulations, or are overly-complex requiring the selection of numerous parameters and supporting calculations prior to the analysis. Most neglect shear deformations by default.
A research initiative was undertaken to develop a nonlinear analysis procedure, VecTor5, for plane frames that accurately accounts for shear effects, but one that does not require extensive pre-selection of analysis options, material models and failure modes nor extensive supporting analyses or calculations prior to the analysis. The procedure developed is capable of considering static loads (i.e., monotonic, cyclic and reversed-cyclic) as well as dynamic loads (i.e., base accelerations, impulse, impact and blast forces, initial mass velocities, and constant mass accelerations). The advantage of the procedure lies in its simple modelling, and inherent and accurate consideration of shear effects. Complete details of the formulation, application and verification of the procedure is provided by Guner (2008).
The analysis and design of reinforced concrete (RC) structures against extreme loads, such as earthquakes, blasts, and impacts, has been an objective of many researchers and designers. As a result of recently elevated terror threat levels in the world, demand for the impact resistant design of buildings has increased. Numerous studies have been conducted to-date for understanding and developing methodologies predicting the behaviour of RC structures under impact loads. However, lack of complete understanding of shear behaviour under high dynamic conditions hindered the efforts for accurate prediction of impact behaviour, since severe shear mechanisms may dominate the behaviour of RC structures when subjected to impact loads.
This study aimed to apply one of the more successful methods of static reinforced concrete shear analysis, the Modified Compression Field Theory (MCFT), to the analysis of dynamic loads, and thus, develop an efficient and reliable tool for impact analysis of RC structures. Two-dimensional nonlinear finite element analysis program for reinforced concrete, VecTor2, developed previously at the University of Toronto for static loads, was modified to include the consideration of dynamic loads, including impacts. VecTor2 uses the MCFT for its computational methodology, along with a wide array of material and behavioural models for reinforced concrete. To verify the performance of VecTor2 and its computational methodology under impact loads, an experimental program was also undertaken to provide data for corroboration. Eight reinforced concrete beam specimens, four pairs, were tested under free falling drop-weights, impacting the specimens at the mid-span. All specimens had identical longitudinal reinforcement, but varying shear reinforcement ratio, intended to investigate the effects of shear capacity on the impact behaviour. A total of 20 tests were conducted, including multiple tests on each specimen. The test results showed that the shear characteristics of the specimens played an important role in their overall behaviour. All specimens, regardless of their shear capacity, developed severe diagonal shear cracks, forming a shear-plug under the impact point. The VecTor2 analyses of the test specimens were satisfactory in predicting damage levels, and maximum and residual displacements. The methodology employed by VecTor2, based on the MCFT, proved to be successful in predicting the shear-dominant behaviour of the specimens under impact.
