Numer 19/4 (2020)
Redaktor: Krzysztof Śledziszewski
Spis treści
Strony
Pobierz
Adam Piekarczyk
Deformability of the masonry subjected to shearing due to vertical displacements
DOI: 10.35784/bud-arch.2141
5 – 16
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Słowa kluczowe

shear |vertical wall displacement |transverse stiffness |shear deformation angle

Streszczenie

The paper presents the results of tests of masonry specimens subjected to vertical displacement, with limited deformations in a direction parallel to the masonry bed joints (horizontally) and additionally compressed in the direction perpendicular to the bed joints (vertically). Specimens in the form of fragments of masonry walls were made of solid ceramic brick and AAC blocks. Studies have shown that the nature of the relationship between wall deformation angles and shear stresses caused by vertical displacements depends on the values of accompanying compressive stresses normal to the plane of the masonry bed joints. Compressive stresses have a positive effect on the load-bearing capacity and crack resistance of this type of masonry walls and the angles of deformation occurring at the moment of cracking. The dependence of the transverse stiffness modulus on the value of shear stresses is strongly non-linear, but with increasing shear stresses, it stabilises at a certain level independent of the values of compressive stresses associated with shear.


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Politechnika Śląska

Kostiantyn Protchenko,
Elżbieta Szmigiera,
Marek Urbański,
Andrzej Garbacz
Mechanical performance of FRP-RC flexural members subjected to fire conditions
DOI: 10.35784/bud-arch.2119
17 – 30
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Słowa kluczowe

Fibre-Reinforced Polymers (FRP) bars |Hybrid FRP bars |FRP-RC beams |Fire resistance of FRP |Fire resistance of FRP-RC members

Streszczenie

One of the main concerns that limit the widespread use of Fibre-Reinforced Polymers (FRP) bars as internal reinforcement for reinforced concrete (RC) structures is their relatively unexplored response to elevated temperatures. The behaviour of FRP reinforcement at elevated temperature as well as their post-fire behaviour can be different from conventional reinforcement and depends on the properties of the constituents of the bars. Therefore, the fire resistance of FRP-RC structures is an important issue that needs careful investigation before FRP reinforcement can be implemented in RC structures.

The experimental results for full-scale FRP-RC beams subjected to specific fire action were presented and discussed in this paper. The specimens were exposed to heat in the mid-section from below (tension zone) and from the sides. As one of the main aims was to examine the influence of different reinforcement configurations, the testing was made for concrete beams reinforced with three different types of FRP bars: (i) basalt-FRP (BFRP), (ii) hybrid FRP with carbon and basalt fibres (HFRP) and (iii) nano-hybrid FRP (nHFRP), with modification of the epoxy matrix of the rebars.

The present work describes the behaviour of FRP-RC beams exposed to fire conditions and simultaneous loading (50% of their ultimate strength capacity at normal temperature) and unloaded beams were tested after the cooling phase in order to evaluate their residual resistance.

Present work shows that the type of FRP bars used has a direct influence on the outcomes and the way of destruction. The maximum ductility, the longest heating time of approximately 100 minutes, was obtained for beams reinforced with BFRP bars and attained deflections were corresponded to the value of 162 mm.

This work was supported by the National Centre for Research and Development. Project “Innovative Hybrid FRP composites for infrastructure design with high durability” NCBR: PBS3/A2/20/2015.


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Kostiantyn Protchenko
Politechnika Warszawska

Elżbieta Szmigiera
Politechnika Warszawska

Marek Urbański
Politechnika Warszawska

Andrzej Garbacz
Politechnika Warszawska

Grzegorz Sadowski,
Piotr Wiliński,
Anna Halicka
Composite beams with indented construction joint – comparison of results of laboratory tests and numerical analysis
DOI: 10.35784/bud-arch.2171
31 – 42
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Słowa kluczowe

composite concrete beam |interface shear resistance |crack |Digital Image Correlation (DIC) |finite element method (FEM)

Streszczenie

The paper presents a comparative analysis of the behaviour of a composite beam, consisting of a precast element with indented surface and new concrete layer, subjected to 4-point bending. The results obtained from the virtual model of the beam created using the finite element method (Abaqus/CEA 2019 software) were compared with the laboratory test results obtained with use of the digital image correlation (DIC) method for identifying the crack pattern. The virtual model of composite beam was calibrated by the choice of interface parameters ensuring that the value of load resulting in delamination between concrete layers was close to that value obtained in the laboratory tests. The comparative analysis showed that the pattern of bending and shear cracks and the pattern of interface crack obtained with the finite element method reflect the laboratory test results properly. It can be assumed that the crack between concrete layers is related to the appearance and propagation of shear cracks. On the basis of FEM analysis it can be concluded that the phenomena identified as “shear friction” and “dowel action” are significantly activated after the interface cracking.

The paper was written as a part of scientific research financed from the statutory funds of the Faculty of Civil Engineering, Mechanics and Petrochemistry of the Warsaw University of Technology.


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Grzegorz Sadowski
Politechnika Warszawska

Piotr Wiliński
Politechnika Warszawska

Anna Halicka
Politechnika Warszawska

Kajanan Selvaranjan,
J.C.P.H. Gamage,
G.I.P. De Silva,
Vajira Attanayaka
Thermal performance of rice husk ash mixed mortar in concrete and masonry buildings
DOI: 10.35784/bud-arch.2121
43 – 52
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Słowa kluczowe

rice husk ash |thermal conductivity |mortar |mechanical properties |SEM

Streszczenie

Rice Husk (RH) is an agricultural waste which is produced in huge amounts from the milling process of paddy rice. Rice husk ash (RHA) is a by-product material obtained from the combustion of rice husk. The amorphous silica-rich RHA (84-90 wt%) has a wide range of applications. This research focused on the possibility of utilizing RHA in the process of developing a mortar with low thermal conductivity to enhance the thermal comfort in concrete and masonry buildings. The thermal conductivity of mortar was determined by Lee’s Disc method, and the results were compared to the data for conventional mortar as well as commercial thermal insulation materials. The results indicate a significant reduction in thermal conductivity in the mortar developed with RHA.

The authors acknowledge the University of Moratuwa for providing the necessary funding required for the research through Exploratory Research Grant scheme by National Research Grant (NRC/PPP/18/01).


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Kajanan Selvaranjan
University of Moratuwa, Sri Lanka

J.C.P.H. Gamage
University of Moratuwa, Sri Lanka

G.I.P. De Silva
University of Moratuwa, Sri Lanka

Vajira Attanayaka
Airow Solutions (Pvt) Ltd, Sri Lanka
Marta Słowik,
Piet Stroeven,
Amanda Akram
Crack mechanisms in concrete – from micro to macro scale
DOI: 10.35784/bud-arch.2147
53 – 66
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Słowa kluczowe

concrete |crack mechanisms |fictitious crack model

Streszczenie

The paper discusses a fictitious crack model of concrete in tension proposed by Hillerborg. This model presents a concept that illustrates the mechanism of crack initiation and its propagation in concrete on meso-level. It has proven to be a very useful tool for practical use, for both numerical and experimental research. The model was derived from findings on crack mechanisms on more advanced micro- and macro-scale, as presented in this paper. One of the paramount issues regarding crack analysis is the influence of aggregate size on mechanical and fracture parameters of concrete, and also on micro-crack development and associated macro-crack formation. Although significant progress in recognizing crack mechanisms in concrete has been achieved, there are still some aspects that should be studied in depth, for example the role of aggregate particles on crack development. This problem is analysed in the paper as well.


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Marta Słowik
Politechnika Lubelska

Piet Stroeven
Technische Universiteit Delft, Holandia

Amanda Akram
Politechnika Lubelska

Andrei Tur,
Viktar Tur,
Stanislav Derechennik,
Aliaksandr Lizahub
An innovative approach to a safety format for the estimation of structural robustness
DOI: 10.35784/bud-arch.2133
67 – 84
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Słowa kluczowe

robustness |progressive collapse |reliability |safety format |pseudo-static response

Streszczenie

The estimation of structural robustness remains one of the most important stages of the design of structural systems. Recommended design strategies for the robustness assessment are based on the provisions specified in the actual EN 1991-1-7 and ISO 2394:2015. Currently, the EN 1991-1-7 and ISO2394:2015 allows the use of indirect tie-force method, but normally, non-linear pseudo-static analysis is widely used, because it is based on more realistic constitutive relations for basic variables, which enables a simulation of the real structural behaviour. Implementation of the non-linear pseudo-static analysis for the assessment of a structural system in accidental design situations requires to adopt a different approach to safety format.

The paper presents an innovative approach to safety format calibration for non-linear analysis of RC-structures subjected to accidental loads. The proposed method of the robustness estimation is based on the joint energy-saving (conversion) approach and the full probabilistic method for the estimation of a safety format for pseudo-static non-linear response of modified (damaged) structural system. The proposed probabilistic considerations are based on the Order Statistic Theory.


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Andrei Tur
Brzeski Państwowy Uniwersytet Techniczny, Białoruś
Viktar Tur
Politechnika Białostocka

Stanislav Derechennik
Brzeski Państwowy Uniwersytet Techniczny, Białoruś
Aliaksandr Lizahub
Brzeski Państwowy Uniwersytet Techniczny, Białoruś
Viktar Tur,
Volha H. Sannikava
Assessment of the early-age strains and stresses in 2D restrained self-stressed members
DOI: 10.35784/bud-arch.2131
85 – 94
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Słowa kluczowe

expansive concrete |strains |stresses |restraint conditions |analytical model

Streszczenie

The paper presents the implementation of the modified strains development model (MSDM) for the two-way restrained self-stressed members such as expansive concrete-filled steel tubes and expansive concrete plane elements with arbitrary orthogonal reinforcement. The analytical approach allows defining the restrained strains and stresses in any 2D restraint conditions by following the iterative procedures and accounting for the elastic-plastic behaviour of expansive concrete at an early age. The consistency of the proposed method was confirmed by assessing the experimental results of the two series of the expansive concrete-filled steel tubes and three series of the expansive concrete plane members with mesh reinforcement in the centre of gravity.


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Viktar Tur
Brzeski Państwowy Uniwersytet Techniczny, Białoruś
Politechnika Białostocka

Volha H. Sannikava
Brzeski Państwowy Uniwersytet Techniczny, Białoruś
Tomasz Waśniewski,
Ewelina Kołodziejczyk
Ductility and internal forces redistribution in lightweight aggregate concrete beams
DOI: 10.35784/bud-arch.2124
95 – 108
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Słowa kluczowe

concrete |lightweight |ductility |redistribution |beams

Streszczenie

Lightweight Aggregate Concrete (LWAC) is typically defined as concrete having a density smaller than or equal to 2200 kg/m3 and can be obtained by mixing natural or artificial lightweight aggregates. There is a general scepticism regarding the use of lightweight aggregate concrete (LWAC) for structural applications. This concern is attached to the more brittle material behaviour which leads to lower ductility.

This article presents a numerical parametric analysis of the behaviour of the reinforced LWAC cross-sections under the immediate load taking into account the density of the LWAC concrete, concrete strength and tensile reinforcement ratio.

Numerical analysis of the beams was conducted in OpenSees, an open–source nonlinear finite element method framework. One-dimensional elements, with three degrees of freedom at each end, were used. Bending stiffness in the integration points was calculated based on the sectional moment – curvature relationship.

The analysis showed that there is a relationship between the ductility of the cross-sections made of lightweight concrete and its density class. It is associated with limited compressive strains and the brittle behavior of LWAC. The limited rotation capacity of the reinforced concrete sections made of LWAC also affects the ability of redistribution of internal forces in statically indeterminate beams.


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Tomasz Waśniewski
Politechnika Łódzka

Ewelina Kołodziejczyk
Politechnika Łódzka

Bogumił Wrana,
Jan Wrana
The buildings of the John Paul II Centre – a challenge for civil engineering and architecture
DOI: 10.35784/bud-arch.2139
109 – 124
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Słowa kluczowe

John Paul II Centre in Cracow |limestone sediments |CFA-type drilled piles |reinforced concrete |natural material solutions |respect for context and identity of the place

Streszczenie

The buildings of the John Paul II Centre (CJPII) are located in Cracow-Łagiewniki on a heap of limestone sediments from the former “Solvay” Sodium Plant in Kraków. The area is called “Białe Morze” (White Seas) and is located in the natural depression of the Wilga river valley, between Św. Józefa hill in the north and Góra Borkowska hill in the southwest. The limestone sediments as a building substrate for CJPII buildings is unprecedented ground in the world and thus a challenge for civil engineering.

The height of the heap reaches about 15 m and has retained the consistency of a white pulp until today. CJPII buildings are objects of the third geotechnical category, founded on a foundation slab of 0.8-m thickness, and in the central part of 0.45-m thickness. The slab is based on 200 reinforced concrete CFA-type drilled piles with a diameter of 1000 mm and 650 mm and length up to 26 m. The load-bearing structure of the CJPII buildings is a reinforced concrete frame and shell structure.

The symbolism of the urban complex (e.g. the scale of the market square in Wadowice) located on a system of 200 piles, above the post-industrial landfill/heaps of sediments – ensuring its protection by architectural solutions referring to places connected with the life of JPII (the Wawel Cathedral, St. Mary’s Basilica in Cracow) with the adopted natural material solutions (brick and white stone) recalling the ways of combining them, and used on the facades of the emerging JPII buildings.


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Bogumił Wrana
Politechnika Krakowska im. Tadeusza Kościuszki

Jan Wrana
Politechnika Lubelska

Qing Zhang,
Graeme J. Milligan,
Maria Anna Polak
Nonlinear finite element analysis of punching shear strength of reinforced concrete slabs supported on L-shaped columns
DOI: 10.35784/bud-arch.2122
125 – 138
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Słowa kluczowe

punching shear |finite element analysis |L-shaped columns |slab openings

Streszczenie

Most current concrete design codes include provisions for punching shear of reinforced concrete slabs supported on columns with L, T, and cruciform shapes. Reference studies verifying the accuracy of these code provisions are typically not provided. Empirical data of punching failures of slabs supported on columns with L, T, and cruciform shapes are limited due to the cost and time required to test specimens with slab thicknesses and column sizes commonly used in practice. In this paper, the punching shear behaviour of five interior L-shaped slab-column connections, one without a slab opening and four with slab openings, subjected to static concentric loading are analyzed using a plasticity-based nonlinear finite element model (FEM) in ABAQUS. The FEM is similar to models previously calibrated at the University of Waterloo and was calibrated considering nine slabs that were tested to study the impact of column rectangularity on the punching shear behaviour of reinforced concrete slabs. The finite element analysis results indicate that shear stresses primarily concentrate around the ends of the L, and that current code predictions from ACI 318-19 and Eurocode 2 may be unconservative due to the assumed critical perimeters around L-shaped columns.

This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the University of Waterloo.


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Qing Zhang
University of Waterloo, Kanada
Graeme J. Milligan
University of Waterloo, Kanada
Maria Anna Polak
University of Waterloo, Kanada

Joanna Zięba,
Lidia Buda-Ożóg,
Izabela Skrzypczak
Factors determining the quality of masonry – differentiation of resistance and reliability
DOI: 10.35784/bud-arch.2127
139 – 150
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Słowa kluczowe

masonry structures |reliability of construction |compressive strength |quality assurance

Streszczenie

A house or any other building without walls is truly hard to imagine. The first thing usually associated with walls is, of course, masonry. Today, masonry walls perform a load-bearing function in buildings up to four above-ground floors, in the higher parts of the buildings they perform a protective and stiffening function. However, there is a widespread opinion that the designer does not have to check the bearing capacity of masonry structures because masonry are were stand, are standing and will stand. Not everyone, however, currently works the wall as it should. The problem is that a lot of emphasis is now placed on reducing construction times. Therefore, there are a number of factors affecting the quality of the masonry structure, which overall reduce their safety. The article presents the influence of the quality of masonry on the differentiation of bearing capacity and reliability of an example masonry structure. The analyses included various values γm of the partial factor, recommended in the national annex PN-EN 1996-1 [1], depending on the category of masonry units, class execution of works and type of mortar. In addition, a decrease in load capacity and reliability caused by the increase of the initial eccentric resulting from the inaccuracy of the masonry wall was examined.


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Joanna Zięba
Politechnika Rzeszowska im. Ignacego Łukasiewicza

Lidia Buda-Ożóg
Politechnika Rzeszowska im. Ignacego Łukasiewicza

Izabela Skrzypczak
Politechnika Rzeszowska im. Ignacego Łukasiewicza

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