This thesis deals with nonlinear analysis of reinforced concrete structures under monotonically increasing loads. Post-cracking behaviour of planar reinforced concrete structures is studied to investigate the tension stiffening phenomenon and the post-cracking shear resistance. The feasibility of using the available bond stress-slip relationships to model the steel-concrete interface behaviour is examined by incorporating these relationships in a three dimensional axisymmetric finite element model and analyzing several reinforced concrete tension specimens. / A finite element model which uses the advanced endochronic stress-strain relationship and incorporates the results of the investigation on post-cracking behaviour and steel-concrete interface behaviour is formulated and used in the analysis of several reinforced concrete members. Analysis results are compared with the available experimental data and with the results obtained by other researchers. Excellent correlation was obtained between the computed values and the experimental results.

No description available.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Civil Engineering / Doctoral / Doctor of Philosophy

Call number: LD2668 .T4 1986 M34 / Master of Science / Civil Engineering

No description available.

A non-linear finite element computer program capable of predicting the complete response of two-dimensional reinforced concrete members was developed. This tool which accounts for the stress strain characteristics of cracked concrete was used to predict the responses of a number of members containing discontinuities. These members included corbels, dapped end beams, beams with web holes, and deep beams. The results of tests performed by the author as well as tests performed by other researchers were compared with the non-linear predictions. In addition, simple strut and tie models suitable for designing regions near discontinuities were developed. The predictions obtained by these models were compared with the non-linear finite element predictions and with the test results.

published_or_final_version / Civil Engineering / Master / Master of Philosophy

Concrete is the most widely used construction material in the world, so the assessment of damage in concrete is critical from the point of view of both safety and cost. Of particular interest are macro cracks that extend through the concrete cover of the reinforcement, which can potentially expose the reinforcement to corrosive elements. The high density of scatterers such as aggregate and voids in concrete makes quantitative imaging with coherent ultrasound difficult. As an alternative, this research focuses on diffuse energy based ultrasonic methods rather than coherent ultrasonic methods for crack depth assessment. Two types of ultrasonic measurements were made on real cracks formed under four point bending: one that focuses on time of flight measurements from an impactor; while the other uses the arrival time of maximum energy in a diffuse field excited by an impulsive load from a transducer. Each of these ultrasonic techniques is used to interrogate a macro crack in a concrete beam, and the results are compared to determine their accuracy and robustness. The actual crack depth is determined using direct surface measurements and a destructive dye-injected approach with drilled cores. The results suggest that the diffusion method, using a maximum energy approach, more accurately estimates the crack than visual inspection and impact echo methods, which overestimate the depth.

A non-linear finite element program to simulate the behaviour of infilled frames and plane stress reinforced concrete members under the action of monotonic and cyclic loading has been developed. Steel is modelled as a strain hardening plastic material, and in the concrete model cracking, yielding and crushing are considered. The separation, sliding, and opening and closing of initial gaps at the interfaces between the frame and the infill panels are accounted for by adjusting the properties of interface elements. The non-linear equations of equilibrium are solved using an incremental-iterative technique performed under load or displacement control. The iterative techniques use the standard and modified Newton-Raphson method or the secant Newton method. An automatic load incrementation scheme, line searches, and restart facilities are included. The capabilities of the program have been examined and demonstrated by analysing five reinforced concrete panels, a deep beam, a shear wall, and eight infilled frames. The accuracy of the analytical results was assessed by comparing them with the experimental results and those obtained analytically by other workers and shown to be good. A study of the effects of some material and numerical parameters on the results of analyses of reinforced concrete deep beam has been carried out. Two techniques have been proposed and used to overcome numerical problems associated with local strain concentrations which occur with the displacement control, when path dependent incremental iterative procedures are used for inelastic materials. The displacement control provided with these modifications has been shown to be more efficient than the load control.