Interaction of ultrasonic waves with partially-closed cracks in concrete structures

Interaction of ultrasonic waves with partially-closed surface-breaking cracks in concrete structures has been studied. Measurements have been conducted on a reinforced concrete beam containing various mechanical-load-induced cracks and compared with the baseline measurements at those locations. Influence of crack width, incident angle of waves...

A mesoscale modelling perspective of cracking process and fracture energy under high strain rate tension

This paper presents a numerical modelling study on the simulation of the cracking process and fracture energy in concrete under high strain rate. To capture the stress wave effect and the damage evolution at the meso-length scale, both a homogeneous model with a millimetre-resolution mesh and an explicit heterogeneous mesoscale model with random...

Drop weight impact strengths of porous concretes investigated with a measurement technique using laser doppler velocimetry

Porous concrete is used in many applications that require permeability, noise absorption or thermal insulation. However, its response under dynamic loading is generally not considered. Porous concrete has a characteristic of forming multiple cracks and subsequently fracturing into small fragments when exposed to impact loading. Therefore, with...

Dynamic tensile resistance of concrete - Split hopkinson bar test

The behavior of concrete structures is strongly influenced by the loading rate. Compared to quasi-static loading, on meso and macro-scale concrete loaded by impact loading acts in a different way. First, there is a strain-rate influence on strength, stiffness, ductility, and, second, there are inertia forces activated which influence the...

Control of cracking in R.C. Structures: Numerical simulation of a squat shear wall

In this paper the behavior of a squat shear wall subjected to monotonic shear loading is investigated. The study fits into the experimental program driven by CEOS.fr on modeling of the behavior of the tested mocks-ups (monotonic and cycling loading-under prevented or free shrinkage). The shear wall has been analyzed with nonlinear finite element...

Results of monitoring large carbon fiber post-tensioning systems in a balanced Cantilever Bridge (Dintelharbour Bridge, The Netherlands)

Steel post-tensioning systems and stay cables are susceptible to corrosion. Carbon fiber systems are not. However, there was no experience on the long term behavior of such post-tensioned elements. Four external tendons (75 m long), stressed to a load of 2650 kN, were applied in a large balanced cantilever bridge and monitored for over 10 years....

Laboratory validation of MEMS-based sensors for post-earthquake damage assessment image

The evaluation of seismic damage is today almost exclusively based on visual inspection, as building owners are generally reluctant to install permanent sensing systems, due to their high installation, management and maintenance costs. To overcome this limitation, the EU-funded MEMSCON project aims to produce small size sensing nodes for...

Crack repair of asphalt concrete with induction energy

It is well known that the healing rates of asphalt courses increase with the temperature. A new method, induction heating, is used in this paper to increase the lifetime of asphalt concrete pavements. Mastic will be first made electrically conductive by the addition of conductive fibers. Then it will be heated via induction energy. This will...

Corrosion monitoring for underground and submerged concrete structures - examples and interpretation issues

Since about 1980 Corrosion Monitoring Systems have been used in many concrete structures in aggressive environmentworldwide. While these systemswork properly in aboveground environment, some questions have arisen for submerged conditions, e.g. the outer sides of tunnels, piers in seawater or foundations in wet soil. One question concerns macro...

Shear and anchorage behaviour of fire exposed hollow core slabs

The fire resistance of hollow core slabs is currently assessed considering flexural failure only. However, fire tests show that shear or anchorage failure can also govern the load bearing behaviour. This paper is based on the dissertation by the author1 and discusses existing and new fire tests. It also presents the development, calibration and...

Dynamic response analysis of concrete structures: Simplified design method and its limitations

The behaviour of dynamically loaded structures, like concrete containment structures and blast resistant control buildings, can be analysed with advanced numerical techniques as well as with less laborious engineering methods. Most used simplified method is the Single Degree of Freedom (SDOF) method, or the so-called Biggs method [1]. This paper...

Numerical modelling and experimental assessment of concrete spalling in fire

In this paper, the phenomenon of spalling of concrete in fire has been studied using a numerical model. Spalling is the violent or non-violent breaking off of layers or pieces of concrete when it is exposed to high temperatures as experienced in fires. The types and mechanisms of spalling have been explained. A numerical model has been developed...

Durability of marine concrete structures - field investigations and modelling

This article presents a series of investigations on six concrete structures along the North Sea coast in The Netherlands. They had ages between 18 and 41 years and most of them were made using Blast Furnace Slag cement. Visual inspections showed corrosion damage in only one structure, related to relatively low cover depths. All structures showed...

Preventive measures against concrete damage to ASR in the Netherlands current state-of-affairs

In CUR-Recommendation 38, various vital measures that need to be taken during design of new concrete-mixtures in order to prevent damage due to ASR in the concrete have been outlined. The most important of these measures are: - the use of blast furnace slag cement (with a high slag content: ≥50% by mass of cement as slag); - or the use of...

Design of concrete structures for durability ; Example: Chloride penetration in the lining of a bored tunnel

To design concrete structures for durability, all relevant performances that the structure has to fulfill and that can be influenced by degradations have to be defined. The probability that a given performance must be delivered within a design service life should also be considered. One of the consequences of the required reliability in the...

Shallow floor construction with deep composite deck: From fire tests to simple calculation rules

This paper deals with an international research project into the fire behaviour of a particular, economically appealing, type of composite steel concrete beams: the shallow floor beams with composite slabs using deep deckings. The results of 3 full scale fire tests are briefly summarised. Based on these fire tests, advanced numerical models have...

A composite plasticity model for concrete

A composite yield function is used to describe the behavior of plain and reinforced concrete in biaxial stress under monotonic loading conditions. A Rankine yield criterion is used to monitor the in-plane tensile stresses and a Drucker Prager yield function controls the compressive stresses. A good agreement with experimental data for biaxial...