Marija Smilović

Numerical Model for Static and Dynamic Analysis of Masonry Structures

Firstly, the main problems of numerical analysis of masonry structures are briefly discussed. After that, a numerical model for static and dynamic analyses of different types of masonry structures (unreinforced, reinforced and confined) is described. The main nonlinear effects of their behaviour are modelled, including various aspects of material nonlinearity, the problems of contact and geometric nonlinearity. It is possible to simulate the soil-structure interaction in a dynamic analysis. The macro and micro models of masonry are considered. The equilibrium equation, discretizations, material models and solution algorithm are presented. Three solved examples illustrate some possibilities of the presented model and the developed software for static and dynamic analyses of different types of masonry structures.

Effect of Anisotropy of Masonry on the Behaviour of Unreinforced and Confined Masonry Walls Under Ground Motion

This paper presents the numerical test results of the effect of anisotropy on the behaviour of unreinforced and confined masonry walls under horizontal harmonic ground acceleration. Two-storey masonry walls with different lengths (3, 6, 12 m) are analysed. The wall foundations are supported on a rigid base, with possibility of lifting. A non-linear macro model of masonry is used. Cases of strong masonry (high strength and stiffness) and weak masonry (low strength and stiffness) are analysed. Different coefficients of anisotropy of masonry ca (0.2, 0.4, 0.6, 1.0) are considered. The excitation period is taken to correspond to the fundamental period of the individual elastic wall. Horizontal displacements at the top of the walls, vertical stresses in masonry and concrete at the bottom of the walls and stresses in the longitudinal bars at the bottom of the vertical ring beams are shown for each analysed case. It is concluded that the ultimate bearing capacity and deformability of walls, as well as stresses in masonry, concrete and reinforcement under dynamic excitation significantly depend on the anisotropy of masonry. It is also concluded that, with the same coefficient of anisotropy, the behaviour of masonry walls depends on its type (unreinforced, confined), height to length ratio (0.5, 1.0, 2.0), and the quality of masonry (strong, weak).

Retrofitting of Three Historic Stone Arch Bridges over the Cetina River in Croatia

Abstract The basic characteristics of the three historic stone arch bridges over the Cetina River in Croatia are presented first. The bridges are under the protection of the Ministry of Culture of the Republic of Croatia as valuable architectural heritage. The current state of the bridges is then presented, and the main solution of the renovation and strengthening of the bridges is briefly explained. A conclusion is reached that the renovation of the bridges was performed successfully, with excellent cooperation between the engineers and the conservators.

The effect of vertical load on seismic response of masonry walls

The effect of the vertical load intensity on the seismic response of masonry walls is numerically investigated. A previously developed numerical model for static and dynamic analysis of masonry structures, which can simulate the most important nonlinear effects of masonry, concrete, reinforcement and soil, was used. Two–storey unreinforced and confined masonry walls, with and without openings, with good and poor quality of masonry, are analyzed. The wall foundations are supported on a rigid base, with possibility of lifting and sliding. The walls are subjected to a real earthquake and harmonic base acceleration. The characteristic displacements of the walls top, stresses in masonry and reinforcement of the vertical ring beams, as well as the state of cracks in the walls, are presented. It was concluded that larger static vertical loads of masonry walls usually have positive effects on their behavior (reducing possible tensile stresses, as well as minimizing the possibility of lifting, sliding and overturning of the walls). However, larger vertical loads generated larger inertial forces on the structure under earthquake excitation. It is more desirable to reduce the vertical load of masonry structures in areas with expected strong earthquakes.

Nonlinear Creep Model for Concrete in Analysis of Plates and Shells

A numerical model for analysis of reinforced and prestressed concrete plates and shells including creep, shrinkage and aging of concrete, already developed by the authors, has been updated with a nonlinear creep model for concrete. The model can be applied for all levels of concrete stresses, while its use for ultimate stress levels is still not fully tested. The presented nonlinear concrete creep model is simple, based on the well known linear model of concrete creep, and intended for simulation of practical concrete structures. For the verification of the presented model, an experimentally tested square concrete plate and cylindrical prestressed concrete shell were analysed numerically. The results of experimental tests at high stress levels and numerical results show good agreement.

Wooden bridge in Trogir

This paper presents the solution for the pedestrian wooden bridge in Trogir. The main span structure consists of two wooden two-hinged arches of 25 m span. All bridge elements are made of natural solid oak wood and connected by traditional carpentry joints. The bridge had to integrate, as much as possible, into the existing historic and natural surroundings of this ancient town.