Abstract:This paper presents the manufacturing and properties of three types of polyolefin fibres: monofilament and fibrillated polypropylene microfibres and macro-synthetic (PP/PE) fibres – today, besides steel and glass fibres, these are the most widely used fibrous reinforcement of cement composites. Different types of fibres result from various methods of improving the low modulus of elasticity and poor adhesion of PP fibres (chemically inert) to the cement matrix. These methods are also described in the paper.
Abstract:Sometimes, deep mining introduces particular seismic risk to buildings on the surface; therefore, special procedures are needed to assess the safety limits of ground motion. This paper demonstrates such a procedure for use when the standard approach fails to properly asses intensity. Peak velocity is chosen to measure seismic intensity. Forecasted and past seismicity is compared with structural damage assessments to make a decision allowing safe mining in a given location.
Abstract:This paper presents the results of numerical analysis of the dynamic response of 12 storey precast concrete apartment buildings of prefabricated system WWP, located in a seismically active mining region in Poland – Legnica-Glogow Copperfield (LGC). The study involved typical buildings and structures after modernisation. The results allowed to assess the influence of the type of structural reinforcements of the buildings on their dynamic response.
Abstract:A number of past and recent observations have confirmed that collisions between adjacent, insufficiently-separated structures occurring as a result of seismic excitation (structural pounding) may result in serious damage to structural elements and can even lead to their total destruction. This paper summarises the results obtained from a shaking table experimental study which investigated structural pounding between three adjacent models of steel towers. The study included different configurations of towers and distances between the structures. The results of the study confirmed that collisions have a significant influence upon the behaviour of the towers, leading to the increase as well as decrease in the structural response.
Pilecka, Elżbieta, Białek, Magdalena, Manterys, Tomasz
Type: Article
Release date:
2016
Abstract:This article discusses the problem of the instability of road embankments. Two types of landslides located in various geotechnical conditions were analysed. The first case is where the stability of the road embankment itself is lost, in which the soil layers under the embankment have no influence. In the other case, the instability of the embankment is connected with landslides of the soil on which a given embankment is situated (slope stability loss). The authors proposed original solutions which were later on verified by MIDAS GTS NX®. The conducted studies show that the proposed protection strategies for both slopes are effective, thus yielding a high coefficient of general stability (FoS).
Abstract:The study presents a selection of free-field vibration measurement results (the horizontal component x vibration is perpendicular to the axis of the track) in the ground surface layer, in one of the three measuring polygons. Pendolino, InterCity and InterRegio trains, excited free-field vibrations. Results for speeds of 120 and 160 km/h were analysed to have comparison that is more tangible.
Abstract:Creating a computational model of the existing building, in which there are non-structural components, taking into account a variety of operating factors, possible reassignment of objects and the accompanying load changes cause doubt about which scheme of work of the partition wall should be applied. This paper presents an analysis of the effect of vibration caused by the use of cars for people staying in the building, depending on the different computational models of heavy type partition walls. The selection of work schemes of elements in the structure is not always clear from its purpose and should be adapted to the purpose it serves. The study shows four alternative models of work and analysis of the partition walls in the building, which use the kinematic loading resulting from car traffic as an ordering criterion adopted for the analysis of computational models, the influence of vibration on people in the buildings in accordance with the PN-88/B-02171 standard. As proved by the calculations performed for the chosen residential building, the differences between the responses applied to the excitation reach several percent. In order to estimate the safely comfort of the inhabitants, the computational model should take into account any possibility of changing the work schemes of elements, which would appear to have no effect on the estimated parameter.
Jakubczyk-Gałczyńska, Anna, Kristowski, Adam, Jankowski, Robert
Type: Article
Release date:
2016
Abstract:Traffic-induced vibrations may cause the cracking of plaster, damage to structural elements and, in extreme cases, may even lead to the structural collapse of residential buildings. The aim of this article is to analyse the effectiveness of a method of forecasting the impact of vibrations on residential buildings using the concept of artificial intelligence. The article presents several alternative forecasting systems for which it is not necessary to carry out laborious and costly measurement tests. The results show that artificial neural networks can be an effective tool for estimating the impact of traffic-induced vibrations on buildings; however, more cases need to be analysed in order to validate the system.
Abstract:In this paper, the thermal dynamic characteristics of exterior walls with variant concrete solutions of load-bearing layer were analysed. The main aim of this study was to compare the amplitudes of wave fluctuations of internal temperature and internal heat flux depending on the construction material used. Calculations were made for partitions with a structural layer made from lightweight concrete composites, autoclaved aerated concrete and reinforced concrete. Very good damping properties were obtained for the partitions made of concrete composites. The obtained data suggests that such solutions provide much smaller fluctuations of temperature and heat flux in comparison to materials with low specific heat.
Abstract:The paper presents the results of laboratory experiments carried out on eight clay brick masonry wallettes of two types under cyclic compressive loading. Based on the results, the failure envelopes were determined, presented and discussed, as were common points stressstrain relationships for both series of specimens. The analytical description of the kinetic of stiffness degradation (with proposed appropriate formulae and experimentally determined parameters) was elaborated and proposed.
