Archives of Civil Engineering

The composite materials as FRP (Fiber Reinforced Polymers), which are characterized by benefits resulting from the combination of high strength reinforcement (as carbon, glass, steel or aramid fibers) with synthetic matrix are increasingly used to reinforce existing structures. Reinforcing System as FRCM (Fibre Reinforced Cementitious Matrix), which includes, among others, Ruredil X Mesh Gold System, is much less commonly used. However, the uniform and practical methods for calculating composite reinforced structures are not determined. Especially when considering the real conditions of structure exploitation, which requires further research in this field. In the paper the initial loading level influence on the efficiency of reinforced concrete beams strengthen using system Ruredil X Mesh Gold was investigated.

The paper presents numerical and experimental research on glulam delamination in a double lap connection with predominant shear stresses. Laboratory tests and wide literature survey enabled to determine timber and glue joint parameters. Cohesive zone theory, generally used for epoxy matrix and fiber reinforced composites, was adopted to modelling glue layer delamination in glulam elements. Numerical models were validated with laboratory tests.

The paper is dedicated to the discussion of elastic coefficients of wood. Parameters for wood presented in the literature are critically evaluated and discussed. The orthotropic mathematical model, with nine different elastic parameters, is one of the most often used models of wood. However, mathematical limitations on these parameters for the correct model are not well known. Based on these limitations, the verification of orthotropic elastic parameters for different species of wood is presented. The analysis shows that the published data are often unclear and sometimes wrong. The attempt to relate experimental results to the mean values specified in the standards is the second aspect considered in this paper. The designer, a user of these standards, should have clear information that the given parameters are specified for specific mathematical model and species of wood. This paper attempts to propose such a classification.

Recycling of plastic wastes helps in reducing waste disposal problems and helps for the sustainable development of the country. Concrete with various % (0 to 55%) of waste plastic aggregates were tested for their mechanical strength properties. In the present work, plastic aggregates obtained as end product of a polymer recycle industry in the form of grains called as plastic aggregates are used as fine aggregate replacements in concrete. The addition of plastic aggregate as fine aggregate replacements results in increase in compressive strength, split tensile strength and flexural strength and thus helps in production of sustainable concrete. It is observed that, the optimum % of replacement of sand with waste plastic waste is 40% and it is also found that upto55% of sand replacements with plastic wastes, mechanical strength values are comparable with that of the normal concrete.

The web-tapered I-columns have the capacity to resist the flexural buckling and lateral torsional buckling at a particular location where as in the rest of the member the capacity is lower. There needs a focusing on the nonprismatic members, to find the buckling capacity and standard procedures are to be framed in Indian Code IS 800:2007. This exploratory research explores simulated finite element models covering a total of 60 web tapered column sections having taper ratios (h₂/h₁) from 1.0 to 3.0 using FEA software ANSYS17.2. With an elaborate Eigenvalue buckling analysis, this research has come up with newer design equation for calculating the buckling load of web tapered I columns. This novel equation could predict the buckling stress for any taper ratio of web tapered I column of any length.

Over the course of operation, asphalt road pavements are subjected to damage from car traffic loads and environmental factors. One of the possible methods of strengthening damaged asphalt pavements may be the application of an additional rigid layer in the form of a cement concrete slab with continuous reinforcement.

This paper presents a material-technological and structural solution for composite pavement where a cement concrete slab with continuous HFRP bar reinforcement is used for strengthening. Based on laboratory tests, the serviceability of composite bar reinforcement of rigid pavement slabs was shown. A design for strengthening asphalt pavement with a concrete slab with steel bar and corresponding HFRP bar reinforcement was developed. The composition of a pavement cement concrete mix was designed, and experimental sections were formed. Based on laboratory tests of samples collected from the surfaces of experimental sections and the diagnostic tests carried out in “in situ” conditions, the authors will try, in the nearest future (Part II: In situ observations and tests), to confirm the effectiveness of strengthening asphalt pavements with cement concrete slabs with HFRP components.

Pavements made of cement concrete, used for road constructions, are damaged during use. This applies to both the pavements of rural and forest roads with very low traffic loads, as well as road pavements with high traffic loads. One of the most effective ways of repairing damaged concrete cement pavements is through placing an asphalt overlay on a concrete slab. In order to increase the fatigue life of the asphalt overlay, asphalt mixtures are modified with fibres. One technological solution is to use FRP (Fiber Reinforced Polymer), an innovative material with improved properties.

The aim of this paper is to assess the impact of asphalt overlays modified with a new type of fibres to strengthen the durability of weakened cement concrete pavement structures.

On the basis of the conducted analyses, it was shown that the use of an asphalt layer reinforcement increases fatigue life, for both 15 cm thick prefabricated slabs and a typical road pavement for average traffic made of 25 cm doweled and anchored concrete slabs. There was a significant increase in the fatigue life of the concrete pavement structure as a result of modifying the overlaid asphalt mixture with FRP fibres.

Over the recent years, there is a growing interest in concrete prefabrication. Many of the currently operating concrete plants have implemented systems that increase the quality of manufactured products, have expanded highly automated production lines and have clearly reduced wastes and energy consumption. However, one of the problems often encountered in the construction industry is the inefficient organization of logistics processes. Proper shipments planning of aggregates consisting of the selection of their appropriate quantity and the aggregate stock, corresponding to the needs of concrete plants should contribute to lowering costs. Therefore, it is necessary to carry out the optimization, the aim of which is to minimize costs, as well as to maximize the fulfillment of the degree of expected needs of concrete plants. This paper presents a model that allows purchase strategy optimization of aggregates with different grain size fraction. For research purposes, three separate aggregate stocks and five different concrete plants are considered.

The article proposes a new approach to the identification of key agents, knowledge and resources required to complete tasks being performed as a part of construction projects. The author used the concept of meta-networks to model the relations between agents, knowledge, resources and tasks of a project. Up until now, the identification of key means of production employed a measure of performance of the project that was modelled using a metanetwork. However, this measure is limited as it does not take into consideration the significance of individual tasks or the relations between them. The author thus proposed a structural modification of the performance measure for the purposes of identifying key agents, knowledge and resources of a planned project. A case study analysis has confirmed the application potential of the proposed approach. In practice, the results that were obtained can aid planners in evaluating the performance of a project's plan. Information about key agents, knowledge and resources can constitute the basis for drafting alternative plans which would be more resistant to failure due to the possible loss of key means of production over the course of carrying out a project.

The growing number of municipal sewage treatment plants in Poland raises the problem of managing more and more sludge. The thermal treatment of municipal sewage sludge (TTMSS), which significantly reduces the volume of waste, results in an increase in the concentration of heavy metals in the fly ashes – the final products of the process. The search for methods of utilization of fly ash from TTMSS resulted in attempts to use it in hardening slurries widely used in hydro-engineering. Due to the nature of the application of this material in the cut-off walls (exposure to groundwater flow) one of the key issues is the degree of heavy metal immobilization. The paper attempted to determine the degree of leaching of selected heavy metals from the hardened hardening slurry, composed of fly ash from TTMSS. For this purpose, the eluates were prepared from samples, after various periods of curing, using a dynamic short-term method called "Batch test". The liquid used for leaching was: distilled water and 0.1 molar EDTA solution – to determine the amount of potentially mobile heavy metal forms. The results show the possibility of the safe usage of fly ash from TTMSS as an additive for hardening slurries.

Particular diligence in the preparation of documentation and conducting a tender procedure for construction works must be made by public contracting entities, who are subject to additional restrictions. In Poland, the largest public contracting entities are the sectoral ones. These are the entities (defined in Art. 3 of the Public Procurement Law Act) operating in the sectors of water management, energy, transport and postal services. The paper presents the analysis of tender offers for the execution of construction works or design and execution of construction works related to the reconstruction, construction and revitalization of railway lines, announced after the amendment to the Public Procurement Law on June 22, 2016. The considered examples are selected tender procedures covering the scope of construction and assembly works on railway lines throughout the country. The authors paid particular attention to the tender criteria applied and the requirements for the potential contractors for works in the field of railway infrastructure.

The construction site and its elements create circumstances that are conducive to the formation of risks to work safety during the execution of works. Analysis indicates the critical importance of these factors in the set of characteristics that describe the causes of accidents in the construction industry. This paper attempts to analyse the characteristics of the construction site to indicate their importance in defining the circumstances of an accident at work. The research was carried out on the basis of data from the register kept by the District Labour Inspectorate in Krakow, Poland. Main substantive tasks include isolating patterns of accidents on site and identifying those of the analysed characteristics that are important in defining these patterns. In terms of methodology, the paper presents a method of analysing data resources by using means of conceptual grouping in the form of cluster analysis.

The paper concerns reliability analysis of steel trusses under fire conditions with taking into account randomness of buckling coefficient, modulus of elasticity's and yield strength's reduction factors. To assess the reliability system analysis was employed. The calculations of appropriate standard deviations of random variables were realized in Mathematica program. Two types of trusses were analysed: statically determinate and indeterminate, so respectively serial and mixed system were used. The results, gotten for different levels of coefficients of variation of reduction factors were presented.

In the paper experimental investigation results of three elements are presented. Two of them were made of reinforced concrete. The strengthened bracket had the steel accessory mounted to cracked loaded corbel (while it was loaded to half ultimate force of the reference element), the reference one was tested without any accessory. The third corbel was the steel accessory mounted to the concrete column. Full scale corbels were 450 mm deep and 250 mm wide, steel accessory was 320 mm high. The aim of the research was to verify the following thesis: short corbels (shear slenderness a_c /h ≈ 0,3) can be strengthened by a steel accessory. Load carrying capacity of strengthened member increased by 40 %. The ultimate force obtained for the steel accessories mounted to concrete column was 66 % of reference value. While testing some observations and measurements (strain of reinforcement and concrete, development of cracking) were made which allowed to describe corbel behaviour under increasing load.

Land surveying is one of the elements of the execution of construction works. These include, among others, the establishment of a horizontal and vertical geodetic control network, an inventory of the existing area, development of a road project and setting out the location of the road in the area. In order to avoid mistakes, construction works should be controlled as part of surveying works during the implementation of a given project. The article attempts to identify and quantify risk factors occurring during surveying at the stage of preparing data from a detailed design. Two proprietary methods have been presented to calculate both the probability value and the consequences of individual risk factors. The advantage of the presented analyzes is the fact that the acquired validity hierarchy of risk factors, expressed in numerical values, can be explained in a scientific way, rather than referring only to possessed knowledge, experience and intuition.

Smoke control solutions are used to maintain tenable conditions in buildings, enabling evacuation process, rescue operations and reducing the thermal stress on the building structure. For last 50-years the design process of such solutions did not significantly change – a required volumetric capacity is calculated with theoretical and empirical models, and further, mechanical design is prepared to deliver this capacity. In this paper, a new approach – “smart smoke control” is introduced, as a system that adapts the performance parameters based on the momentary measurements of temperature in the building. The system follows the growth and decay of fire in the building, which allows optimization of its mechanical parameters, and provides substantial increase in the performance. This paper provides a discussion on traditional and new concepts in smoke control, and defines areas, in which a paradigm shift must occur, to enable widespread adoption new and more efficient solutions. The paper does also refer to previous proof of concept studies, presenting the preliminary assessment of the performance of a smart smoke control system.