Modelling dynamic tensile failure of quasi-brittle materials using stress-enhanced nonlocal models

The development of realistic numerical tools to efficiently model the response of concrete structures subjected to close-in detonations and high velocity impacts has been one of the major quests in defense research. Under these loading conditions, quasi-brittle materials undergo a multitude of failure (damage) mechanisms. Dynamic tensile failure...

Damage to Grass Covered Slopes Due to Overtopping

Many dike failures have been ignited by damage due to erosion on the landward slopes. This paper investigates how grass covered slopes perform when being attacked by overtopping flow during storm surges. Based on observations during a number of simulator tests, damage is classified into three types 'head-cut', 'roll-up' and 'collapse' depending...

Overtopping on Grass Covered Dikes: Resistance and Failure of the Inner Slopes

A large part of the Vietnamese population is living close to the coast. The sea is an essential source for supporting lives. Coastal flooding, on the other hand, threatens the people, land and infrastructures every year. Some hundreds years ago, the first sea dikes were built in Thai Binh and Nam Dinh provinces. In the north, the coastline is...

Chemomechanics of Damage Accumulation and Damage-Recovery Healing in Bituminous Asphalt Binders

As a contribution to the development of mutli-scale multi-physics approaches to modelling pavement performance, the present thesis considers the topic of damage accumulation accompanied by damage recover self-healing of the bituminous asphalt phase of pavement systems. It is found insightful that by adopting Hveem’s [1943] concept of attributing...

Multiscale material model for asr-affected concrete structures

One of the most harmful degradation process for concrete structures is the alkali-silica reaction. This process starts at aggregate level with a gel swelling and can produce damage up to macro level, by compromising the integrity and capacity of the structure. In order to better understand the complex nature of this phenomenon, a multiscale...

The great eastern Japan earthquake and Tsunami: Field observations on the coast of Tohoku six month later

The tsunami that hit the north pacific coast of Japan on March 11, 2011 has been characterized as a mega disaster. It inundated over 560 square kilometers of land, devastating a large number of coastal communities, causing over 20,000 casualties and huge economic damage in Tohoku region. The purpose of this report is to give insight into the...

Numerical assessment of concrete damage: Procedures and pitfalls

The paper focuses on the quality of predicting the damage characteristics of the loaded engineering structure by subjecting section images of cores supposedly drawn from the concrete of the structure to quantitative image analysis by sweeping test lines. Automation of this data acquisition stage is shown, generally leading to information that is...

Multiscale failure modelling of quasi-brittle materials

The conventional multiscale homogenization theory, which has mainly been applied to determine constitutive laws for bulk materials, suffers from two drawbacks when applied to softening materials. Firstly, the coarse scale response is sensitive to the finite element mesh used to discretize the coarse scale domain. Secondly, increasing the size of...

Wave overtopping resistance of grassed slopes in Viet Nam

The Simulator was applied to test the resistance against wave overtopping of grass covered dike slopes in Viet Nam. Observation and measurement during destructive tests were performed to investigate the development process of damage induced by overtopping flow. Damages were likely to be initiated at transition of either geometry or materials, at...

A Continuous–Discontinuous Approach to Simulate Heat Transfer in Fractured Media

A macroscopic framework to model heat transfer in materials and composites, subjected to physical degradation, is proposed. The framework employs the partition of unity concept and captures the change from conduction-dominated transfer in the initial continuum state to convection and radiation-dominated transfer in the damaged state. The...

Finite element analysis of damage in pipeline bends

The present paper describes a numerical formulation for the analysis of damage in steel pipeline bends. In particular, the numerical implementation of Gurson plasticity model is described in the framework of a special element, referred to as “tube element”. This is a three-node element, which simulates pipe behavior combining longitudinal...

Continuous-Discontinuous Modelling of Failure

The foundations of a safe structural design lie on the understanding of failure processes of engineering materials and in their correct representation. In a numerical context, failure representation in engineering materials can be pursued either in a continuous or in a discontinuous setting. Both approaches can model certain failure modes, but...

Design philosophy of concrete linings for tunnels in soft soils

Stability of stones in the top layer of a granular filter: Literature survey

In order to understand the processes involved in damaging a granular filter, the behaviour of the separate particles it is made of must be known. The hydrodynamic forces on the particles are very important for understanding this behaviour. These forces have been examined by many researchers. Chapter 2 deals with that aspect. The characteristics...