Słowa kluczowe

concrete |testing maschine |concrete compressive strength |destructive method |water-cement ratio

Streszczenie

This paper presents the analysis of the results of research on concrete compressive strength on cubic samples, in the early stage of its curing (after 7, 14, and 28 days). The analysis considers the variable water-cement ratio. Statistical and strength parameters were assessed, estimating the quality of the obtained concrete at the same time. Verification of the expected C25/30 concrete grade was carried out from the recipe provided by the prefabrication plant. Then, the grammage of individual components was adjusted to obtain the grade of concrete assumed by the authors. The article estimates the concrete grade based on strength parameters in three stages of concrete curing. The concrete was then compared with the concrete class calculated based on standard procedures (EC2 procedures), which could be reached after 28 days.

The paper also provides an overview of the most used methods of testing concrete compressive strength.

Słowa kluczowe

stabilization of cohesive soils |a hydrophobizing agent |diamidoamine lactate |frost resistance |capillary absorption

Streszczenie

The paper presents the results of tests on capillary water absorption of mixtures from cohesive soils - clayey sand and sandy clay - stabilized with cement and the addition of a hydrophobic binder. Studies have shown that the appropriate addition of diamidoamine lactate allows to limit the penetration of water inside the stabilized samples, which increases their frost resistance. The mixtures with the additive showed lower capillary water absorption compared to the mixtures stabilized only with cement, especially in the first few hours after soaking with water.

Słowa kluczowe

energy consumption |building energy efficiency |energy performance

Streszczenie

The first part of the article presents the upcoming changes in the regulations regarding energy consumption by single-family housing. Current and forthcoming requirements in 2021 for building insulation and maximum EP primary energy demand factor were indicated. The second part of the paper presents the results of research aimed at determining what type of heat source for heating purposes and the type of ventilation will be able to meet the latest requirements. The analysis was based on the determination and comparison of the EP factor in the considered single-family building for selected heating variants assuming two different types of ventilation: gravitational and mechanical supply-exhaust with heat recovery system. Based on the results obtained, an attempt was made to determine the tendency of changes in the design of single-family buildings in terms of choosing the type of heating and ventilation.

Słowa kluczowe

reinforced concrete structures |effective width of flange |minimum cross sectional area of reinforcement |PN-EN 1992-1-1:2008 |PN-B 03264:2002

Streszczenie

The article analyses the impact of modeling the cross-section of two-nave and two-storey reinforced concrete frame with dimensions: 18.0 m × 32.0 m as a bars on the results of bending moments, the value of elastic deflection and dimensioning of reinforcement due to bending. Six options were considered: a beam as a rectangular section and five T-beam variants with different definition of effective flange width. The differences in obtained results were commented. Conclusions useful for the designing of reinforced concrete structures were presented. The procedure for determining the effective flange width in the context of PN-EN 1992-1-1:2008 and PN-B 03264:2002 standards with a commentary on the use of effective flange width in calculations and construction of reinforcement in reinforced concrete structures were described. Brief description of determining the reinforcement due to bending according to simplified method given in PN-EN 1992-1-1:2008 was presented. In addition, the standard formula for determining the minimum cross sectional area of reinforcement (9.1N) in PN-EN 1992-1-1:2008 with a proposal for its strict determination for the T-beam with a flange in the tensile zone was analyzed.

Słowa kluczowe

frost resistance |fracture energy |high strength concrete |fiber |fiber reinforced concrete

Streszczenie

Knowledge of fracture mechanics parameters can help for a more accurate assessment of frost degradation of high-strength concrete. High strength concretes, despite the tight structure, are characterized by increased brittleness. Cracks in the concrete structure are places of accumulation of significant stresses. Additional stresses resulting from cyclic freeze/thaw stimulate the material destruction processes. The basic strength parameters of concrete do not take into account structural defects of the material and do not give a complete description of susceptibility to damage caused by, e.g., frost degradation. This study aimed to determine the relationship between frost degradation of high-strength concretes and changes in the value of their fracture energy associated with the initiation of cracking after 150, 250, 350 and 450 freeze/thaw cycles. The research was carried out using 100 × 100 × 400 mm samples, with a pre-initiated 30 mm deep notch. The I load model under a three-point bending test was used, based on the procedure recommended by RILEM. Concrete with a compressive strength of 90 MPa with steel fibres and a mixture of steel and basalt fibers was tested. The obtained results allow for the evaluation of frost degradation using fracture energy G_F and critical crack tip opening displacement CTOD_c.

Słowa kluczowe

passive sunspace systems |heating demand |ISO 13790 |dynamic simulations

Streszczenie

The calculation method presented in ISO 13790 was developed during the research project PASSYS. It aimed to work out the way of estimating energy demand while taking into account different passive solar systems. The standard includes two calculation methods for sunspaces – a full and simplified method. They differ in terms of basic assumptions and the treatment of solar gains in the sunspace and conditioned rooms. There are some doubts about the interpretation of equations presented in the standard, especially when it comes to modelling the solar radiation distribution within the solar space. The paper presents a discussion on the basic hypotheses applied in full and simplified methods, together with the author’s suggestions regarding modifications to the ISO 13790 calculation methods. The modified methods allowed to satisfactorily predict the functioning of the exemplary sunspaces with a smaller area of glazed partitions and higher radiation absorptivity of the casing, that is spaces similar in terms of solar radiation utilisation to traditional living spaces. The phenomena typical for sunspaces with a high degree of glazing, such as the retransmission of reflected radiation, were not sufficiently taken into account in the calculation methods of the standard.

Słowa kluczowe

digitalization of heritage buildings |laser scanning |Historical Building Information Modelling |point cloud |3D modelling

Streszczenie

The aim of the paper is to present some experiences of using modern technologies to historical buildings digitalization. The emphasis is placed on the possibilities of spatial data collecting, as well as on subsequent 3D modelling. The paper describes the proposed survey techniques which are based on the Terrestrial Laser Scanning and photogrammetry. The authors obtained the point cloud by using the laser scanner Faro Focus 3D and dedicated software to combine scans (target based and cloud to cloud methods). The paper also provides an introduction to issues related to a method of building structure modelling based on a point
cloud. The authors proposed some computer software tools that could improve work with a point cloud and the modelling process. The resulting 3D model could be both a source of information about historical building and a sufficient base to create computational model with spatial finite elements. The subject of the case study is the St. Hubert Chapel located in Rzeszów (Poland) and built in the middle of the 18th century under the patronage of the Lubomirski family. This rococo chapel is one of the most valuable architectural monuments in the region. Historical Building Information Model (HBIM) could be helpful in analysis, visualisations and conservation practice of this precious monument. Diagnosing the current object state and assessing its technical condition could be the purpose of creating a computational FEM model.

Słowa kluczowe

multisensory research |multisensory space |public space |Praga – Północ

Streszczenie

The concept of multi-sensory perception of cities is one of the elements shaping the complete image of the city. It is an aspect as important to the recipient as the urban structure. The study of the multisensory record of public spaces gives a better chance to understand: the identity of the place, the changing dimensions of cultural heritage, local social problems, and even conditions influencing spatial decisions. Multisensory research has an implementation value and can be an important, previously unaccounted for factor, influencing the revitalization program and planning decisions. Therefore, it is so important to analyze the available literature on the subject, conduct scientific observation of the research area, create a proposal for a hybrid research methodology on multi-sensory recording of space and determine their relationship with activities in the field of urban planning. The trial area – selected public spaces of the Praga – Północ district in Warsaw was adopted according to predetermined criteria, the most important of which were: authentic urban tissue, downtown area, architectural and functional diversity of buildings.