Bruno Massicotte

Ultra-high performance fibre reinforced concrete mix design in central Canada

The mix design of ultra-high performance fibre reinforced concretes (UHPFRC) produced with locally available materials in Quebec and Ontario is presented. The procedure and results of the optimization of self-consolidating UHPFRC are discussed. The characterization of the retained mixes is presented with regards to strength, heat of hydration, shrinkage, chloride ion permeability, and freeze–thaw resistance. The results show that it is possible to produce self-consolidating UHPFRC with the targeted properties for use in precast products and in situ applications without requiring heat or pressure treatment during curing.

Seismic Performance of Code-Designed Fiber Reinforced Concrete Joints

An experimental investigation is presented on the use of steel fiber reinforced concrete to provide ductility in beam-to-column joints during earthquake excitation. Four full-scale exterior beam-column joints, part of a prototype building designed according to the National Building Code of Canada, were tested under cyclic reverse loading. The first specimen was made of normal concrete but ignored all the special seismic recommendations related to the spacing of lateral reinforcement in the beams, columns, and joints. The second specimen was also made of normal concrete and incorporated full seismic details. The third and fourth specimens were similar to the first one but used steel fiber reinforced concrete in the joint region. Experimental results indicated that fiber reinforced concrete is an appealing alternative to conventional confining reinforcement. Steel fibers bridging across cracks in the concrete mix increase the joint shear strength and can diminish requirements for closely spaced ties. The performance of a joint is closely related to the volume content and aspect ratio of the fibers.

Geometrical interpretation of the arc-length method

The arc-length method is a powerful solution technique becoming increasingly popular among researchers and engineers. This method is presented here as a particular case of a more general formulation which includes all other solution strategies. The arc-length method is derived in its continuous and discrete formulations. Two versions of the arc-length method (Crisfield and Ramm) are presented and compared using a geometrical interpretation. Advantages and disadvantages of each method are pointed out. A new method, called the modified Crisfield-Ramm method, is proposed. This improved arc-length method combines the advantages of the two parent methods.

Modeling and Testing Influence of Scaling Effects on Inelastic Response of Shear Walls

Monotonic and cyclic quasi-static testing was performed on ductile reinforced concrete shear-wall specimens designed and detailed according to the seismic provisions of the National Building Code of Canada and CSA-A23.3-04. The tests were carried out on full-scale and 1:2.37 reduced-scale wall specimens. The behavior under cyclic loading was characterized by ductile flexural response up to a displacement ductility of 4.0. At this deformation level, inelastic shear deformations in the plastic hinge contributed to approximately 20% of the total deformation. In the subsequent cycles, strength degradation took place due to shear sliding developing along the large flexural cracks at the wall base. Shear sliding was not observed under monotonic loading and the specimens exhibited significantly higher ductility capacity. Excellent agreement was found between prototype and reduced-scale walls. The inelastic response and failure mode observed under cyclic loading could be adequately reproduced using a finite element analysis program. Simpler models with frame elements and lumped plastic hinges could capture the wall flexural response well, but shear deformations could not be reproduced.

Nonlinear analysis of composite bridges by the finite element method

Abstract The study of the nonlinear behaviour of composite bridges is quite complex. The difficulties can be attributed to the use of various materials and structural components and to their behaviour under different loading conditions. A sophisticated numerical tool is therefore required to improve our understanding of the structural behaviour of bridges. The finite element method is a powerful one which can be adopted to fulfill this task. In this paper, a plate/shell element (called DLTP), a shear connector element and a contact element for the nonlinear analysis of composite bridges are presented. The finite element procedure is based on small elasto-plastic strains and updated Lagrangian formulation to account for the large displacements and rotations of the structures. Various material models are developed to simulate the behaviour of steel, concrete and interface media (shear connectors, contact and friction) as well as phenomena encountered in the analysis of composite bridges. Numerical examples are presented for the validation of the proposed analytical procedure.

Strengthening of reinforced concrete beams with composite materials: theoretical study

This paper deals with the flexural strengthening of reinforced concrete beams by means of composite thin plates. It presents a theoretical model which was developed to study the effects of various parameters on the flexural behavior of strengthened beams. From a parametric study carried out with the model, it was found that the most significant parameters affecting the ultimate flexural resistance are the concrete compressive strength, the percentage of reinforcing steel, the modulus of elasticity of the composite material and the thickness of the strengthening plate. To avoid brittle flexural failure of strengthened beams, limiting quantities of strengthening material are specified as a function of a strengthening index.

Modeling the thermal stresses at early ages in a concrete monolith

The paper presents details of an experimental and numerical study of thermal strains and induced stresses in large-scale mass concrete. Three large-scale monoliths were built on a dam construction site in the James Bay Territory (Canada) to monitor the thermal behavior of mass concrete subjected first to heat of hydration development and subsequent freeze and thaw cycles. The monoliths were instrumented with thermocouples and mechanical strain gages.

Analysis and Design of Straight and Skewed Slab Bridges

Results of an investigation aimed at determining bending moments and shear forces, required to design skewed concrete slab bridges using the equivalent-beam method are presented in this paper. Straight and skewed slab bridges were modeled using grillage and finite-element models to characterize their behavior under uniform and moving loads with the objective of determining the most appropriate modeling approach for design. A parametric study was carried out on 390 simply supported slabs with geometries covering one to four lane bridges of 3- to 20-m spans and with skew angles ranging from 0 to 60°. The analyses showed that nonorthogonal grillages satisfactorily predict the amplitude and the transverse distribution of longitudinal bending moments and shear forces, and can be used for the analysis of skewed slab bridges. Results of the parametric study indicated that shear forces and secondary bending moments increase with increasing skew angle while longitudinal bending moments diminish. Equations are prop...

Static and Dynamic Behavior of High- and Ultrahigh-Performance Fiber-Reinforced Concrete Precast Bridge Parapets

New designs of precast bridge parapets made with fiber-reinforced concrete (FRC) were developed using nonlinear finite-element calculations. Specific properties of high- and ultrahigh-performance FRC were exploited in these designs. The conventional reinforcement required in the FRC precast parapets varied from 0 to 50% when compared with a reference built-on-site parapet. An extensive experimental program was carried out to verify the performance of the FRC precast parapets. The parapet mechanical behavior was established under quasi-static tests and under dynamic loading replicating a vehicle impact. The results of the quasi-static tests indicate that precast FRC parapets possess the required strength and have ductility comparable to reference parapets. Quasi-static tests carried out after the dynamic tests indicate that the residual strength of the parapets corresponds to 75 to 100% of their original capacity. The finite-element model adopted in the project satisfactorily reproduced the strength, stiffness, and failure mode of the parapets. Finally, the system efficiency of precast FRC parapets was established for their application in a typical urban bridge project, considering the mechanical performance, the fabrication costs, and the required installation time.

Development of a Reliability Framework for the Use of Advanced Nonlinear Finite Elements in the Design of Concrete Structures

AbstractThis paper proposes a methodology that uses advanced nonlinear finite-element analysis for determining a global resistance factor for the design of reinforced concrete structures. It introduces a new reliability approach that takes into account the uncertainties of the material properties and the performance of the concrete model used in the calculations. In the proposed approach, the global resistance factor is computed following a procedure in which the coefficient of variation of the calculated resistance is estimated using Rosenblueth’s point-estimate method. The robustness and simplicity of the method are demonstrated through validation examples. It is seen that good approximations of the resistance factor can be achieved for the case of normal or quasi-normal distributions of the resistance. Estimation of the coefficient of variation of the prediction error is then performed for a given reinforced concrete element and a nonlinear finite-element package. The accuracy of the selected software ...