Nowoczesne rozwiązania konstrukcyjne hal łukowych dla budownictwa rolniczego

The paper presents evaluation methods of arch-shaped corrugated steel roof capacity used in an agricultural construction. The arch-shaped corrugated steel roof is easy to install, to use and less expensive than the traditional construction of agricultural buildings. The specific of structure poses many design problems related to the local buckling of profiled sheets. The article presents normative design methods, the most common design errors, trends research methods and numerical calculations.W artykule zaprezentowano metody oceny nośności nowoczesnych konstrukcji hal łukowych stosowanych w budownictwie rolniczym.  Cienkościenne łukowe blachy stalowe są proste w montażu, łatwe w eksploatacji i tańsze od tradycyjnych konstrukcji budynków rolniczych. Specyfika zadaszeń z cienkościennych blach łukowych nastręcza jednak wiele problemów projektowych. Rozwiązanie tych problemów pozwoli na wznoszenie tanich i bezpiecznych  budynków. W artykule przedstawiono normatywne metody projektowania, najczęstsze błędy projektowe oraz kierunki rozwoju metod projektowania wspomaganych badaniami

Modern solutions of arch-shaped construction for agricultural building halls

The paper presents evaluation methods of arch-shaped corrugated steel roof capacity used in an agricultural construction. The arch-shaped corrugated steel roof is easy to install, to use and less expensive than the traditional construction of agricultural buildings. The specific of structure poses many design problems related to the local buckling of profiled sheets. The article presents normative design methods, the most common design errors, trends research methods and numerical calculations

Experimental Investigation of Adhesion Failure between Waterproof Coatings and Terrace Tiles under Usage Loads

This paper analyses the mechanism of the loss of functional properties of water-impermeable products used under ceramic tiles bonded with adhesives. Recorded damages were caused by selected ageing factors and were measured by the loss of adhesion of individual layers of the set. The analyzed phenomenon is found mainly on terraces and balconies located in a mid-European transitional climate, i.e., exposed to temperatures passing through 0 °C for three seasons a year. The tests reflected the action of three main functional factors, i.e., temperatures, water and freeze/thaw cycles. Tested waterproof coatings were grouped into three types, i.e., dispersion, cementitious and reaction resin-based products. Research kits consisted of liquid-applied water-impermeable products laid on a concrete substrate, adhesives and tiles. Comparing the effects of the action of the above-mentioned ageing factors revealed that water has the greatest impact on the reduction of the tensile adhesion strength of such sets. The adhesion of waterproof coatings to the concrete substrate showed higher values than the adhesion between the waterproof coating and the tile adhesive layers, regardless of the coating material. Both for samples not exposed to ageing factors, and for those exposed to such impacts, failure usually occurred in the adhesive layer or between the tile adhesive and the waterproof coating, without damaging the waterproof layer. The loss of adhesion of finishing layers to the substrate was not accompanied by a loss of tightness of the waterproof coating. The impact of negative water ageing was particularly destructive on the adhesion of cement-based tile adhesives to waterproof coatings made of polymer with a water dispersion of absorbability above 7% (V/V). There was no correlation among the results of adhesion of the finishing layers to the waterproofing layer after the action of the three ageing factors, i.e., water contact, elevated temperature and freeze/thaw cycles

Numerical Prediction of Local Instability in Double Corrugated Profiles

The technological process of forming the double-corrugated structures of the K-span system causes deep transverse embossing on the surface of the profiles. Such profile geometry makes it difficult to apply classical theories related to plastic failure mechanisms to identify the formation of local instabilities. This article presents an original method for the prediction of local instabilities of double-corrugated structures. The method was developed on the basis of a hierarchical validated FEM model. The geometrically and materially nonlinear analysis method was adopted to perform numerical calculations. The results of calculations enabled the determination of reference equilibrium paths for the eccentrically compressed shell element. Based on the analysis of nonlinear equilibrium paths, a method for predicting the beginning and the end of the appearance of local instabilities in the elastoplastic pre-buckling range was developed

Efficiency assessment of horizontal damp proof courses made by chemical injection in wall tests

This paper discusses one method of prevention of capillary water rising through the walls, i.e., making horizontal damp-proof courses by chemical injection. The aim of the tests was to find out which materials and groups of injection methods give the opportunity to create the most effective secondary horizontal damp proof course of underground parts of walls. The tests were carried out on large samples, i.e., walls built under ideal laboratory conditions of water capillary rise, i.e., with the repetitive properties of the materials used to build the test’s walls, without its additional salinity. The nine randomly selected injection products were tested as two product groups: silanes and silicates. Tested silanes and/or siloxanes products were in the form of cream or paste, silicates were in the form of emulsions or dispersions. They were injected into walls with both methods, i.e. gravity and low pressure. Visible effects of the action of the damp-proof courses usually occur after 90 days after injection of products into the wall. A faster increase in efficiency was found for single-row injection than for double-row injection but with higher values after the end of the study for double injection. According to the density of injection products, the highest efficiency was found for products with a density range of 0.92 kg/dm3 up to 0.96 kg/dm3, for silanes products and with a density less than 1.2 kg/dm3 for silicate products

Resistance of External Thermal Insulation Systems with Fire Barriers to Long-Lasting Weathering

Fire barriers are used to reduce the risk of fire spreading over façades. External thermal insulation composite systems consist of mineral wool strips embedded in a layer of another thermal insulation material. A system configured in this manner, beyond standard solutions, can be more susceptible to environmental factors. In this study, an expanded polystyrene-based system with a mineral wool fire barrier was subjected to weathering conditions. In view of climate change, nonconventional long-lasting exposure simulating the effects of intensive atmospheric factors was applied. Two exposure sequences were used, each covering 80 cycles of heating and wetting, five cycles of heating and cooling, and 30 cycles of wetting, freezing, and thawing. Significant changes were observed in the first sequence. The second sequence caused rendering system cracks wider than 0.2 mm. This indicated a loss of watertightness. A new approach of 3D scanning with inspection analysis was used to assess the deformations. It showed deformation amounted to 0.7 mm within the MW strip. The methods used previously did not allow this level of deformation to be recorded

Doświadczalne i obliczeniowe podejście do oceny struktur łukowych z blach podwójnie giętych. Przegląd najnowszych osiągnięć

Double corrugated, self-supporting K-span arch structures are now commonly used globally to make roofs for building structures, as an alternative to traditional solutions. The K-span system has become popular mainly due to the simple and cheap method of its manufacturing and quick installation. Nowadays, new versions of the system are created but still there is no valid design method. Design difficulties are among the causes of failures or even collapses of such structures. Back in the 1970s, the first studies were developed concerning computational analyses of double corrugated arch roofs. They laid grounds for the development of contemporary K-span system technology but have since lost their practical advantages due to changing engineering conditions. The paper presents a review of research and computational methods concerning double corrugated arch structures. The paper discusses selected scientific studies, which were used as the basis for the development of research and computational methods, and their contemporary continuation. Directions for further research and analyses are also presented which could contribute to the future development of science and engineering in the area and could provide inspiration for future studies.Podwójnie gięte, samonośne struktury łukowe systemu K-span, stosowane są obecnie na runku światowym do wykonywania zadaszeń obiektów budowlanych jako alternatywna technologia w odniesieniu do tradycyjnych rozwiązań. System konstrukcyjny K-span zyskał popularność głównie z powodu prostej i taniej metody wytwarzania oraz szybkiego montażu. Obecnie powstają nowe odmiany tego sytemu, jednak nadal brak jest odpowiedniego sposobu projektowania. Trudności w projektowaniu są jedną z przyczyn awarii a nawet katastrof tego typu struktur. W latach osiemdziesiątych ubiegłego stulecia powstały pierwsze opracowania studialne dotyczące analiz badawczych i obliczeniowych zadaszeń łukowych z blach podwójnie giętych. Stanowiły one podstawy rozwoju dzisiejszej technologii systemu K-span, jednak straciły walory praktyczne z uwagi na zmieniające się uwarunkowania techniczne. Artykuł stanowi przegląd rozwoju technik badawczych i obliczeniowych dotyczących struktur łukowych z blach podwójnie giętych. W artykule przedstawiono wybrane prace naukowe, które były podstawą rozwoju technik badawczych i metod obliczeniowych a także ich współczesną kontynuację

Ammonia in Fly Ashes from Flue Gas Denitrification Process and its Impact on the Properties of Cement Composites

The paper presents the results of research on the properties of fly ashes from the process of flue gas denitrification by selective non-catalytic reduction (SNCR), consisting of dosing urea into the coal combustion chamber. The research was carried out on two types of fly ash: Silica fly ash from flue gas denitrification and ash from a traditional boiler without the flue gas denitrification process. The scope of comparative studies included physicochemical and structural features of ashes, as well as slurries and mortars with the addition of ashes. Fly ash from denitrification, whose ammonia content at the time of sampling was 75 mg/kg at the maximum, was examined. Our own research has shown that fly ash from flue gas denitrification is characterized by a higher value of losses on ignition and ammonia content in comparison to ashes without denitrification. It was shown that the ammonia content in the analyzed range does not limit the use of fly ash as an additive to cement and concrete

Application of 3D Digital Image Correlation for Development and Validation of FEM Model of Self-Supporting Arch Structures

Many building structures, due to a complex geometry and non-linear material properties, are cumbersome to analyze with finite element method (FEM). A good example is a self-supporting arch-shaped steel sheets. Considering the uncommon geometry and material profile of an arch (due to plastic deformations, cross section of a trough, a goffer pattern), the local loss of stability can occur in unexpected regions. Therefore, the hybrid experimental-numerical methodology of analysis and optimization of arch structures have been proposed. The methodology is based on three steps of development and validation of a FEM with utilization of a digital image correlation (DIC) method. The experiments are performed by means of 3D DIC systems adopted sequentially for each measurement step conditions from small size sections, through few segment constructions up to full scale in situ objects