Numerical analysis of structural behavior of welded wire reinforcement in reinforced concrete beams

Thesis (M.S.) University of Alaska Fairbanks, 2016Modernization and industrialization have paved the way for the construction industry of India to expand. On the other hand the Indian construction industry is set to face an acute workforce shortage. The shortage of construction workers has in fact slowed down the growth of this industry in major cities across the country and escalated its cost by 40 percent. An alternative way to replace the labor force is by automation techniques. This study is a numerical analysis to evaluate structural behavior of simply supported concrete beams reinforced with welded wires in comparison with mild steel reinforced concrete beams. Welding conventional steel bars (60 ksi) reduces their shear strength by 50 percent. Welded Wire Reinforcement (80 ksi), with its greater strength, higher durability, significantly lower placing and overall cost, provides an alternative and perhaps a better substitution for mild steel bars. The commercial finite element analysis program, ABAQUS, was used to model the non-linear behavior of reinforced concrete beams. In order to evaluate the structural behavior of welded wire reinforced concrete beams, different configurations of longitudinal and transverse wires have been considered. First, different types of stirrup configurations in a rectangular reinforced concrete beam are compared with a conventional reinforced beam. Second, a structurally performing welded wire configuration is compared with a Mexican chair styled reinforcement configuration. This part of the analysis is evaluated for a T–beam, used for building roof applications.Chapter 1 Introduction -- Welded Wire Reinforcement -- Traditional Rebar versus Welded Wire Reinforcement (WWR) -- Potential Gains through Welded Wire Reinforcement (WWR) -- Welded Wire Reinforcement Specifications and Nomenclature -- Welded Wire Reinforcement Manufacturing, Handling and Placing -- Aim and Scope -- Outline of Thesis -- Chapter 2 Literature Review -- Impact of Welded Wire Reinforcement in Structural Members -- Welded Wire Reinforcements in Columns -- Welded Wire Reinforcements in Beams and Girders -- Welded Wire Reinforcements in Structural Walls -- Summary -- Chapter 3 Finite Element Modeling of Reinforced Concrete Beams -- ABAQUS Modeling -- Non-linear Behavior of Concrete -- Uniaxial and Biaxial Behavior -- Non-linear Modeling of Reinforced Concrete Beam -- Material Model Properties -- Concrete Damage Plasticity Parameters -- Reinforcement Properties -- Convergence Analysis -- Chapter 4 Numerical Analysis of Concrete Beams Reinforced with Traditional and Welded Wire Reinforcement -- Introduction -- Initial Validation and Mesh Convergence -- Analysis of Welded Wire Reinforcement Grids in Reinforced Concrete Beams -- Rectangular Reinforced Concrete Beams Subjected to Four Point Loading Condition -- Rectangular Reinforced Concrete Beams Subjected to Uniformly Distributed Loading Condition -- T - Beams Subjected to Four Point Loading Condition -- Chapter 5 Conclusion and Recommendation -- Conclusion -- Recommendation -- References

Offshore anchor piles under mooring forces: numerical modeling

A parametric study was carried out to study the behavior of offshore anchor piles under mooring forces in dense sand using a three dimensional (3-D) finite element model (FEM). The Mohr–Coulomb plastic model has been used to model the soil, and has been calibrated based on the centrifuge tests discussed in a Ph.D. thesis (published by Ramadan in 2011). The selection of model parameters and comparison of calibrated results with the centrifuge test results are discussed. In the parametric study, different pile lengths and diameters were considered to have different pile–soil rigidities. The pile was loaded at different load inclination angles to examine a wide range of loading conditions. From the current parametric study, design methods and design recommendations are given to help in improving the design of offshore anchor piles under monotonic mooring forces

Modelling and Optimising of a Light-Weight Rockfall Catch Fence System

Rockfall catch fence is a mechanical barrier system that is used at the foot of cliffs to stop and retain falling rocks from reaching nearby infrastructures. A typical system comprises of a high tensile strength wire mesh that is anchored to the ground by rigid posts and strengthened to the lateral and upslope sides by anchoring tension cables. Additional components, such as shock absorbers, might be added to improve the system capacity to dissipate energy. This multi-component system characterises by geometrical complexity and high nonlinear response to impact loads. A light-weight catch fence system is a simple system that can be easily installed in a time efficient manner using manpower rather than heavy machinery, which makes it ideal for railways located in mountainous and difficult terrain regions where there is difficulty in accessing sites with limited workspaces and restricted installation times. However, this should be combined with a proper design to ensure that the system provides the required protection to impede falling rocks from reaching the train lines. In this paper, a parametric study based on finite element analysis is developed to optimise the design of a light-weight catch fence system that has an energy absorption capacity of up to 100 kJ

A Mathematical Model of Heat Transfer in Partially Insulated Airways in Deep, Frozen Ground Placer Mines

Large seasonal variations in the temperature of the ventilating air in mines in the arctic cause changes in the original thermal field through heat and mass exchanges between the air and the surrounding medium. These thermal interactions have major influence on climatic quality as well as on the stability of the mine openings. Thawing of walls and roof in mine airways can be reduced by various types of thermal-insulation. Application of thermal-insulation prevents deep thawing of the rockmass surrounding an airway. In this case, the mechanism of heat transfer around a frozen, underground airway would be much different. A model of heat transfer in a deep, partially insulated airway has been developed and analyzed using finite element methods. Results of the analysis show that without any thermal control, there will be stable change in temperature around the mine airway. With different insulations on the walls of the airway, roof thawing can be reduced and in certain cases, completely eliminated

Development of a continuum plasticity model for the commercial finite element code ABAQUS

The present work relates to the development of computational material models for sheet metal forming simulations. In this specific study, an implicit scheme with consistent Jacobian is used for integration of large deformation formulation and plane stress elements. As a privilege to the explicit scheme, the implicit integration scheme is unconditionally stable. The backward Euler method is used to update trial stress values lying outside the yield surface by correcting them back to the yield surface at every time increment. In this study, the implicit integration of isotropic hardening with the von Mises yield criterion is discussed in detail. In future work it will be implemented into the commercial finite element code ABAQUS by means of a user material subroutine

Remodeling of Fibrous Extracellular Matrices by Contractile Cells: Predictions from Discrete Fiber Network Simulations

Contractile forces exerted on the surrounding extracellular matrix (ECM) lead to the alignment and stretching of constituent fibers within the vicinity of cells. As a consequence, the matrix reorganizes to form thick bundles of aligned fibers that enable force transmission over distances larger than the size of the cells. Contractile force-mediated remodeling of ECM fibers has bearing on a number of physiologic and pathophysiologic phenomena. In this work, we present a computational model to capture cell-mediated remodeling within fibrous matrices using finite element based discrete fiber network simulations. The model is shown to accurately capture collagen alignment, heterogeneous deformations, and long-range force transmission observed experimentally. The zone of mechanical influence surrounding a single contractile cell and the interaction between two cells are predicted from the strain-induced alignment of fibers. Through parametric studies, the effect of cell contractility and cell shape anisotropy on matrix remodeling and force transmission are quantified and summarized in a phase diagram. For highly contractile and elongated cells, we find a sensing distance that is ten times the cell size, in agreement with experimental observations.Comment: Accepted for publication in the Biophysical Journa

An internal variable constitutive model for the large deformation of metals at high temperatures

The advent of large deformation finite element methodologies is beginning to permit the numerical simulation of hot working processes whose design until recently has been based on prior industrial experience. Proper application of such finite element techniques requires realistic constitutive equations which more accurately model material behavior during hot working. A simple constitutive model for hot working is the single scalar internal variable model for isotropic thermal elastoplasticity proposed by Anand. The model is recalled and the specific scalar functions, for the equivalent plastic strain rate and the evolution equation for the internal variable, presented are slight modifications of those proposed by Anand. The modified functions are better able to represent high temperature material behavior. The monotonic constant true strain rate and strain rate jump compression experiments on a 2 percent silicon iron is briefly described. The model is implemented in the general purpose finite element program ABAQUS