Langjährige Messung von Kraft‐ und Verformungsgrößen in Neotopf‐Gleitlagern einer Spannbetonstraßenbrücke. Brückenlager‐Monitoring

Longterm Measuring of Forces and Displacements in Elastomer Pot Sliding Bearings of a Prestressed Concrete Road Bridge. Monitoring of Bridge Bearings Two bearings of a three span prestressed concrete road bridge over the lake Aa in the City of Münster were equipped with elastomer pot sliding bearings with measuring devices during the erection in 1987/88, that are able to measure the distance between sliding slab and covering slab and the rotation of the covering slab. Moreover there are dynamometers, which measure the compression stress of the silicone oil in the pot under the elastomer. With these measuring devices the load history of the bearings during the time of erection of the bridge was monitored. In the 18 years that the bridge is in operation, the bearings have been monitored with these measuring devices. Following the completion of the bridge and further in intervals of some years the loads and displacements of the bearings were monitored especially during lorries were crossing the bridge. The bearings show only minimal attrition after 18 years in use.     

Zur Ermittlung der rißbreitenbeschränkenden Bewehrung bei Zwang in erhärtenden Betonbauteilen: Die Problematik einer “ausreichenden” Mindestbewehrung

Determination of Crack Width limiting Reinforcement due to Constraint in Hardening Concrete If restraint‐induced tensile stresses can occur, for the guarantee of the serviceability and durability the appearing crack width has to be limited due to the purpose and the environmental conditions of the building up to now in accordance to DIN 1045 (Edition 7.88), section 17.6, and furthermore to DIN 1045‐1 (2001‐07), section 11.2. The control of a defaulted crack width has a key position within the standard for durability and serviceability of the structures. The parallel selection of constructive or concrete‐technological measures for the decrease of the restraint stresses is always reasonable, because the defaulted crack widths can be hold and in consideration of the minimum reinforcement und crack injection the building costs can be optimized. Although in the following only the limitation of crack width of early restraint stresses will be considered in the planning of bearing structure the development of further tension situation have to be included. For example, in external building members under winter conditions restraint strain can occur which lead to a crack force in connection with higher tensile strength, for which the minimum reinforcement is not sufficient.     

Endotoxin,extracellular polysaccharides,and β(1‐3)‐glucan concentrations in dust and their determinants in four European birth cohorts: results from the HITEA project

Early‐life exposure to microbial agents may play a protective role in asthma and allergies development. Geographical differences in the prevalence of these diseases exist, but the differences in early‐life indoor microbial agent levels and their determinants have been hardly studied. We aimed to describe the early‐life levels of endotoxin, extracellular polysaccharides (EPS), and β(1‐3)‐glucans in living room dust of four geographically spread European birth cohorts (LISA in Germany, PIAMA in the Netherlands, INMA in Spain, and LUKAS2 in Finland) and to assess their determinants. A total of 1572 dust samples from living rooms of participants were analyzed for endotoxin, Penicillium/Aspergillus EPS, and β(1‐3)‐glucans. Information on potential determinants was obtained through questionnaires. Concentrations of endotoxin, EPS, and β(1‐3)‐glucans were different across cohorts. Concentrations of endotoxin and EPS were respectively lower and higher in INMA than in other cohorts, while glucans were higher in LUKAS2. Season of sampling, dog ownership, dampness, and the number of people living at home were significantly associated with concentrations of at least one microbial agent, with heterogeneity of effect estimates of the determinants across cohorts. In conclusion, both early‐life microbial exposure levels and exposure determinants differ across cohorts derived from diverse European countries.