Pavao Marović

Pullout capacity of spatial anchors

This paper discusses the pullout capacity of spatial anchors in soil under applied vertical force. In field tests, the pullout forces were gradually increased and the ground surface displacements measured in two profiles perpendicular to each other. The laboratory and field tests were performed for several embedment depths and anchor diameter ratios in the same sand and under the same conditions. The anchor pulling was also laboratory‐tested so that the vertical anchor displacements were given and the corresponding force intensity measured. The finite element method was used for the pullout force computation in test cases. The relations between displacements and pullout forces obtained by the laboratory tests, field tests and numerical computations were statistically analysed. Owing to gradual convergence of pullout forces towards the limit value, the exponential function was adopted as an approximation curve. The two obtained constants of the function represent the significant mechanical characteristics. The first is limit pullout force and the second gives the total stiffness of the soil mechanical system.

Modified Mohr‐Coulomb – Rankine material model for concrete

Purpose – The main aim of this paper is to present a three‐dimensional numerical material model for concrete which combines plasticity with a classical orthotropic smeared crack formulation. A further aim is to raise a discussion leading to the creation of a comprehensive computer programme for the analyses of reinforced and prestressed concrete structures.Design/methodology/approach – A new numerical material model for concrete is developed and main theoretical explanations are given to aid in understanding the algorithm. The model is based on Mohr‐Coulomb criterion for dominant compression and Rankine criterion for dominant tension influences. A multi‐surface presentation of the model is implemented which permits the rapid convergence of the mathematical procedure. The model includes associated and non‐associated flow rules, strain hardening and softening where the development of the plastic strain was described by the function of cohesion.Findings – Provides information about developing a new numerical...

Some aspects of 2D and/or 3D numerical modelling of reinforced and prestressed concrete structures

Purpose – To provide an insight in one relatively simple and efficient numerical model for analysing reinforced and prestressed concrete structures, and to raise a discussion leading to the creation of one universal and robust 3D algorithm.Design/methodology/approach – A new numerical model for analysing reinforced and prestressed concrete structures is developed and main theoretical details are described to aid the understandings. The approach is clear, easily readable and the body of the text is divided into logical sections starting from theoretical explanations ending in the large number of different practical examples.Findings – Provides information about developing new and relatively simple numerical model for analysing reinforced and prestressed concrete structures, indicating what can be improved. Recognises the lack of knowing real behaviour of 3D concrete and starts a discussion on it.Research limitations/implications – The knowledge of the 2D and especially 3D concrete behaviour is still poor a...

Finite element solution improved by full clamping element functions

Presents a procedure for obtaining an improved finite element solution of boundary problems by estimating the principle of exact displacement method in the finite element technique. The displacement field is approximated by two types of functions: the shape functions satisfying the homogeneous differential equilibrium equation and the full clamping element functions as a particular solution of the differential equation between the nodes. The full clamping functions represent the solution of the full clamping state on finite elements. An improved numerical solution of displacements, strains, stresses and internal forces, not only at nodes but over the whole finite element, is obtained without an increase of the global basis, because the shape functions are orthogonal with the full clamping functions. This principle is generally applicable to different finite elements. The contribution of introducing two types of functions based on the principle of the exact displacement method is demonstrated in the solution procedure of frame structures and thin plates.

Analysis of Shear Strength of Wood

This paper presents the analysis of different types of shear strength of wood which can differ very much due to its structure and different orientations of applied load. These combinations of wood structure and load orientations lead to different modes of fracture. The main aim of the paper is to find a relation among all types of shear strength of the wood and to reduce the number of shear tests. Furthermore, different shear strengths will be analyzed both experimentally and numerically, i.e. experimentally by testing appropriate specimens and numerically with the help of the finite element structural analysis solver Robot AutoDesk. The testing specimens will be loaded parallel and perpendicular to the wood fibres and the radial and tangential planes will be analyzed. The paper will also investigate the relation to other strengths of wood (i.e. tensile strength parallel and perpendicular to the fibres) in order to simplify the testing procedure for shear strength determination.