Search

BackgroundExposure to air pollution can affect the health of individuals with respiratory disease, but may also impede the health and performance of athletes. This is potentially relevant for people travelling to and competing in the Olympic and Paralympic Games (OPG) in Paris. We describe anticipated air quality in Paris based on historical monitoring data and describe the impact of the process on the development of monitoring strategies for future international sporting events.MethodsAir pollutant data for July to September 2020–2023 and pollen data for 2015–2022 were provided by Airparif (particulate matter (PM2.5), nitrogen dioxide (NO2) and ozone (O3)) and RNSA stations in the Paris region. Airparif’s street-level numerical modelling provided spatial data for the OPG venues.ResultsThe maximum daily mean PM2.5was 11±6 µg/m3at traffic stations, below the WHO recommended daily air quality threshold (AQT). Daily NO2concentrations ranged from 5±3 µg/m3in rural areas to 17±14 µgm3in urban areas. Near traffic stations, this rose to 40±24 µg/m3exceeding the WHO AQT. Both peaked around 06:00 and 20:00 UTC (coordinated universal time). The ambient O3level exceeded the AQT on 20 days per month and peaked at 14:00 UTC. The main allergenic taxa from June to September was Poaceae (ie, grass pollen variety).ConclusionAir pollutant levels are expected to be within accepted air quality thresholds at the Paris OPG. However, O3concentrations may be significantly raised in very hot and clear conditions and grass pollen levels will be high, prompting a need to consider and manage this risk in susceptible individuals.

ABSTRACT The flexural strength of a reinforced concrete beam can be increased by bonding a FRP sheet to the tension face. Nevertheless, this type of reinforcement may cause a premature [...]

Abstract The use of near surface mounted (NSM) fibre reinforced polymer (FRP) is a promising technology for increasing flexural strength of reinforced concrete (RC) members. This paper deals with strengthening [...]

In the present paper, the experimental deflection of cross-laminated timber floors exposed to fire is predicted with the use of advanced and simplified methods. The accurate modelling is based on heat transfer prediction and reduced stiffness, while the simplified methods are based on reduced cross-section method (RCSM) of EN 1995 1-2 (CEN, 2004). All methods are combined with a thick plate theory for laminates in order to compute the mid-span deflection of the floors. The more accurate modelling returned a better agreement with the experimental reference than RCSM approaches. Finally, a RCSM approach based on the time dependency of the zero stiffness layer is suggested.

ABSTRACTThis research explores the possibilities of wood composite structures with a view to designing durable lightweight composite decks. The paper examines a new wood structure technology in which an ultra-high-performance fiber-reinforced concrete (UHPFRC) slab is fastened to glulam beams. Fasteners representing most existing groups are first experimentally investigated on small beams (span one meter). The modes of functioning of each type and the various failure modes are identified. The paper proposes a method for assessing the interface shear stiffness. This method is based on analysis of flexural test results using a slip versus shear stress relation. It is shown that glued assembly of the two materials yields the best shear stiffness and highest ultimate strength. The practical aspects of surface preparation before gluing are considered. The results of a bending test carried out on a composite structure having a span of three meters, made of UHPFRC glued to two glulam beams, validate this fastening technique.

ABSTRACTAn experimental set-up at a reduced scale was carried out in laboratory. This device reproduces the action of tamping on ballast. In these experiments, we highlight the frequency influence. Three different behaviours were observed depending on the frequency: a stiff behaviour at low frequencies: the grains motion is mainly due to the tightening loading effect. A liquid behaviour at high frequencies: vibrations effects are very significant, ballast opposes therefore little resistance to the tightening loading. A viscous behaviour at intermediate frequency: for this range of frequencies, vibrations and tightening force have the same importance.