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The main objective of the study was to estimate the mean horizontal wind action on a façade scaffolding on the basis of full-scale data. Measurements of climatic parameters were carried out for a number of façade scaffoldings (120 structures) located in Poland over a 30-month period. The measurement points were located on 2–3 deck levels of each structure and at 2–4 points placed in each level. The measurements were carried out 3–4 times during each day for 5 consecutive days. At each point, two components of wind speed were measured: first with the vane probe directed perpendicular to the façade and then parallel to the façade. Each measurement lasted 60 s, and the data were recorded every 1 s. On the basis of wind speeds, a procedure was suggested that enabled estimation of the static wind action on façade scaffoldings. The responses of structures to this action were computed via FEM simulations. The results were compared with those based on the approaches recommended by the wind and scaffolding codes. Initial analyses, illustrated by three scaffoldings without a protective cover, indicated large discrepancies between the approaches and the possibility of wind action, which is not considered in the codes.

The paper presents a method of determination for the probability of a scaffold failure at maximum loads which are measured in one week. The research concerns scaffolding which were used on construction sites. The method assumes that the geometries (including imperfections) are deterministic and are compliant with the conditions measured on the construction site. The material properties of the scaffolding components, which cannot be measured, are generated from the normal distribution. Failure is treated as a random event occurring when one component or a group of components fails. The failure event is described by a set of serial diagrams concerning stands, transoms, and additional elements, as well as a mixed diagram concerning a wall anchoring. Probabilities of a failure were determined for 120 scaffolding and their values were obtained in a range from 10-9 to almost 100. A positive or negative evaluation of the scaffolding depends on the level of the acceptable risk of failure. If reliability predictor (parameter similar to reliability index) is equal to 4.7, 41% of the scaffolds used for 12 weeks do not ensure safety of construction workers. If the reliability predictor is equal to 3.5, the percentage of unsafe scaffolds is 17%. The presented results concern frame scaffolds, erected next to elevations and forming planes. It is probable that for frame scaffolds with more complex geometries and modular scaffolds, the results will be different.

This paper presents an analysis of scaffolding response to static wind action, based on different approaches. The static wind load was adopted according to Eurocode standard that required separate calculations for the load acting perpendicular (load case B) and parallel (load case C) to the facade of the building on which the scaffolding was attached. In the second approach, the wind load was calculated on the basis of in-situ measurements performed on scaffolding structures set on construction sites (load case A). The research was carried out on 61 facade scaffolding structures without protective covers. Models of every scaffolding were created in the Finite Element system, based on their real geometry taken from geodetic measurements. Static-strength analysis allowed comparison of the scaffolding response determined by node displacements, normal stress and axial force in structural elements. It was found that in most of the analyzed cases the wind load based on Eurocode approach resulted in the greatest axial force or normal stress in elements. In a few cases, the load based on in-situ tests caused greater response of the structures and the permissible stress and axial force value in the elements were exceeded. These scaffolding structures were usually detached from the wall and twisted out of plane. Analyses pointed out that the scaffolding during its operational use could experience a load other than perpendicular or parallel to its facade as it is given in Eurocode.

Work in unfavorable, changing environmental conditions negatively affects people working on scaffoldings used on construction sites, which may increase the risk of occurrence of dangerous situations. The purpose of this article is to show the scale of temperature changes which workers are exposed to. The paper compares examples of temperature measurements obtained from a metrological station and during tests on scaffoldings located in the Lodz and Warsaw regions. This article also presents the methodology of examining environmental parameters of the surroundings where employees work on scaffoldings. Analysis results show that high temperatures and significant temperature variations frequently occur on the scaffoldings, which leads to a lack of adaptability and consequently to tiredness or decreased alertness. Unfavorable environmental conditions can lead to behaviors which, in turn, can cause accidents.

This article shows incidents associated with the use of gas as an energy carrier. It presents selected incidents which have occurred in Poland and around the world in recent decades. Based on this, consequences of gas and air mixture explosions were analysed as well. The article presents the main causes of gas incidents which have taken place, as per instances which are similar worldwide. Incidents associated with the use of gas are not frequent, but at the same time very tragic as they often lead to illness or even death. In Poland, in the last twenty years, construction area disasters caused by gas explosions account for only 5% of all which have occurred, but the number of fatalities resulting from these cases is approximately 14%. The number of individuals injured reached 39% of all construction disaster victims. Considering all these facts, it is necessary to undertake wide preventive measures in order to increase safety in the use of gaseous fuels.

This paper concerns an approach to model the ledger-stand joints of modular scaffolds. Based on the analysis of the working range of the ledger (represented by a linear relationship between load and displacement), two models of the ledger-stand joint are analysed: first - with flexibility joints and second - with rigid joints and with a transition part of lower stiffness. Parameters are selected based on displacement measurements and numerical analyses of joints, then they are verified. On the basis of performed research, it can be stated that both methods of joint modelling recommended in this paper, can be applied in engineering practices.

This paper describes the results of static non-linear calculations in reference to a typical facade scaffolding. The influence of the dimension and localisation of imperfections was analysed in the researches. It was found that the geometrical imperfections cause the increase of internal forces, and the highest increase occurs in the lowest elements. Higher normal stresses were also obtained when imperfections were modelled as regular horizontal displacements of decks than in the case, when they were arranged according to the form of buckling. The magnitudes of imperfections primarily influence the increase of the internal forces in the standards of frames and bracings. Internal forces in bracings are responsive mainly to imperfections parallel to the scaffolding, regardless of the type of load. In contrast, internal forces in standards are sensitive to imperfections in any direction, but mainly when the scaffolding is subjected to a vertical load.

Experimental studies were performed on ringlock scaffolding joints. The most characteristic element of these joints is a rosette, which provides a temporary connection between the vertical standard and the ledger. Laboratory tests were performed using a typical testing machine and a grip handle developed by the authors, which allows loading the ringlock scaffolding joint with any type of load, regardless of the manufacturer of the scaffolding considered and the material used. A normal force, a shear force in horizontal plane, a shear force in vertical plane, a bending moment in vertical plane, a bending moment in horizontal plane, and torque were applied to the joint. The obtained data could be used to determine the load-bearing capacity of the joint, as well as the nature of the connection. In cases of bending in horizontal plane and torque, the joint should be treated as a hinge, whereas the connection is semi-rigid in case of bending in vertical plane. Four different approaches were employed for determining the joint stiffness. By analysing various modes of joint damage, critical elements could be identified, which could then be used as comparative data when analysing damages to actual structures. Additionally, laboratory tests investigating the material characteristics of individual joint elements were performed. Each joint element had different material characteristics, particularly the ledger end because it was manufactured via moulding.

The purpose of this paper is to show the influence of incorrect scaffolding foundations on the stress in their elements. Static stress analysis was performed for exemplary steel façade scaffolding. The scaffolding was formed using the Plettac 70 system and was composed of 16 modules and 13 working levels. The total dimensions of the scaffolding were 45.0 × 26.36 × 0.74 m. The scaffolding was set up partly on concrete and partly on a created ground classified as coarse sand with discontinuous graining. The boundary conditions modelling the foundation considered the heterogeneity of the ground both along the scaffolding and in the direction perpendicular to the façade. The effect of uneven subsidence on the scaffolding frames was checked, adopting a constant stiffness of 3500 kN/m in half of the supports, while in the rest of them the stiffness varied from 35 to 3500 kN/m. Due to additional bending moments, normal stresses in stands and transoms of the frames increased. Incorrect scaffolding foundation has the greatest negative effect on normal forces in anchors and bracings. Because these elements are responsible for the stability of the scaffolding, their damage may result in scaffolding failure and would certainly lead to a reduction of the values of free vibration frequencies, thus resulting in the discomfort of the workers on the scaffolding and a lack of safety.

People on construction scaffoldings work in dynamically changing, often unfavourable climate. Additionally, this kind of work is performed on low stiffness structures at high altitude, which increases the risk of accidents. It is therefore desirable to define the parameters of the work environment that contribute to increasing the construction worker occupational safety level. The aim of this article is to present how changes in microclimate parameters on scaffolding can impact the development of dangerous situations and accidents. For this purpose, indicators based on the human thermal balance were used. However, use of this model under construction conditions is often burdened by significant errors or even impossible to implement due to the lack of precise data. Thus, in the target model, the modified parameter was used – apparent environmental temperature. Apparent temperature in the proposed Scaffold Use Risk Assessment Model has been a perceived outdoor temperature, caused by the combined effects of air temperature, radiative temperature, relative humidity and wind speed (wind chill index, heat index). In the paper, correlations between component factors and apparent temperature for facade scaffolding with a width of 24.5 m and a height of 42.3 m, located at south-west side of building are presented. The distribution of factors on the scaffolding has been used to evaluate fitting of the microclimate model. The results of the studies indicate that observed ranges of apparent temperature on the scaffolds frequently results in a worker’s inability to adapt. This leads to reduced concentration and increased fatigue, adversely affects health, and consequently increases the risk of dangerous situations and accidental injuries, {"references":["Central Statistical Office, 2016, Accidents at work. Information and statistical studies (in Polish), Warsaw.","B. Hoła, Jakościowe i ilościowe modelowanie wypadkowości w budownictwie, Wydawnictwo Uniwersytetu Wrocławskiego, Wrocław, 2008 (in Polish).","B. Hoła, M. Szóstak, \"An Occupational Profile of People Injured in Accidents at Work in the Polish Construction Industry\", Procedia Engineering 208 (2017) 43–51.","K. Maarten van Aalst, \"The impacts of climate change on the risk of natural disasters,\" Disasters, vol. 30, no. 1, 2006, pp. 5−18.","S. Coccolo, J. Kämpf, J. L. Scartezzini, D. Pearlmutter, \"Outdoor human comfort and thermal stress: A comprehensive review on models and standards\", Urban Climate, Volume 18, December 2016, Pages 33-57.","R.D. Brown, T.J. Gillespie, Microclimatic Landscape Design: Creating Thermal Comfort and Energy Efficiency, Wiley 1995.","P. Höppe, \"The physiological equivalent temperature - a universal index for the biometeorological assessment of the thermal environment\", Int. J. Biometeorol., 43 (1999), pp. 71-75).","AP Gagge , AP Fobolets , LG Berglund, A Standard Predictive Index of Human Response to the Thermal Environment, ASHRAE Transactions 92, 1986, s. 709–731.","J. Pickup, R. De Daer, An outdoor thermal comfort index (OUT_SET*) - Part I – The Model and its Assumptions, (w:) R. de Dear, J. Kalma, T. Oke, A. Auliciems (red.), Biometeorology and Urban Climatology at the Turn of the Millenium. Selected Papers from the Conference ICB-ICUC'99, Sydney, 8–12 Nov. 1999, WMO, Geneva, WCASP-50, s. 279–283.\n[10]\tK. Blazejczyk, MENEX_2005. The Updated Version of Man-Environment Heat Exchange Model, 2005.\n[11]\tK. Błażejczyk, P. Broede, D. Fiala, G. Havenith, I. Holmér, G. Jendritzky, B. Kampmann, A. Kunert, \"Principles of the new Universal Thermal Climate Index (UTCI) and its application to bioclimatic research in european scale\", Miscellanea Geographica 14, 2010, Pages 91-102.\n[12]\tF.R. d'Ambrosio Alfano, B.I. Palella, G. Riccio, \"Thermal Environment Assessment Reliability Using Temperature — Humidity Indices\", Industrial Health, 49 (2011), pp. 95 – 106.\n[13]\tNational Weather Service, www.weather.gov\n[14]\tR.G. Steadman, \"The assessment of sultriness. Part I: A temperature-humidity index based on human physiology and clothing science\", J Appl Meteorol 18, 1979, pp. 861–87.3\n[15]\tL.P. Rothfusz, The heat index equation. NWS Southern Region Technical Attachment, SR/SSD Fort Worth Texas, 990, pp. 90–23. \n[16]\tP.A. Siple, C.F. Passel, \"Measurements of dry atmospheric cooling in subfreezing temperatures\", Proceedings American Philosophy Society, 89, 1945, pp. 177–199.\n[17]\tK. Błażejczyk, A. Kunert, Bioclimatic conditioning of recreation and tourism in Poland, Polish Academy of Sciences, 2011, in Polish.\n[18]\tE. Błazik-Borowa, J. Szer, \"Basic elements of the risk assessment model for the occurrence of dangerous events on scaffoldings,\" Przegląd budowlany, vol. 10, 2016, pp. 24–29, in Polish.\n[19]\tM. Jabłoński, J. Szer, I. Szer, E. Błazik-Borowa, \"Acoustic climate on scaffolding,\" Materiały budowlane, vol. 8, 2017, pp.32–34.\n[20]\tE. Błazik-Borowa, J. Bęc, A. Robak, J. Szulej, P. Wielgos, I. Szer, \"Technical factors affecting safety on a scaffolding,\" in Towards better Safety, Health, Wellbeing, and Life in Construction, Emuze Fidelis, Behm Mike Ed. Bloemfointein: Department of Built Environment Central Universitty of Technology, 2017, pp. 154–163.\n[21]\tP. Jamińska-Gadomska, T. Lipecki, J. Bęc, E. Błazik-Borowa, \"In-situ measurements of wind action on scaffoldings,\" The Proc. Of European-African Conference on Wind Engineering, Liege, Belgium, 2017.\n[22]\tK. Czarnocki, E. Błazik-Borowa, E. Czarnocka, J. Szer, B. Hoła, M. Rebelo, K. Czarnocka, \"Scaffold use risk assessment model for construction process safety,\" in Towards better Safety, Health, Wellbeing, and Life in Construction, Emuze Fidelis, Behm Mike – Bloemfointein Ed. Department of Built Environment Central University of Technology, 2017, pp. 275–284.\n[23]\tI. Szer, E. Błazik-Borowa, J. Szer, \"The influence of environmental factors on employee comfort based on an example of location temperature,\" Archives of Civil Engineering, vol. LXIII, 2017, pp. 193-174.\n[24]\tI. Szer, J. Szer, P. Cyniak, E. Błazik-Borowa, \"Influence of temperature and surroundings humidity on scaffolding work comfort,\" in Prevention of Accidents at Work, Ales Bernatik, Lucie Kocurkova, Kirsten Jørgensen, Ed. Taylor & Francis Group, 2017, pp. 19–23."]}

Scaffolding is a specific construction with high susceptibility to low frequency vibrations. The numerical model of scaffolding presented in this paper contains real imperfections received from geodetic measurements of real construction. Boundary conditions were verified on the basis of measured free vibrations. A simulation of a man walking on penultimate working level as a dynamic load variable in time was made for verified model. The paper presents procedure for a choice of selected parameters of the scaffolding FEM model. The main aim of analysis is the best projection of the real construction and correct modeling of worker walking on the scaffolding. Different boundary conditions are considered, because of their impact on construction vibrations. Natural vibrations obtained from FEM calculations are compared with free vibrations measured during in-situ tests. Structure accelerations caused by walking human are then considered in this paper. Methodology of creating numerical models of scaffoldings and analysis of dynamic effects during human walking are starting points for further considerations about dynamic loads acting on such structures and effects of these loads to construction and workers, whose workplaces are situated on the scaffolding.

The paper deals with the calibration method of FEM subsoil model described by the constitutive Cam-Clay model. The four-storey residential building and solid substrate are modelled. Identification of the substrate is made using research drilling, CPT static tests, DMT Marchetti dilatometer, and laboratory tests. Latter are performed on the intact soil specimens which are taken from the wide planning trench at the depth of foundation. The real building settlements was measured as the vertical displacement of benchmarks. These measurements were carried out periodically during the erection of the building and its operation. Initially, the Cam Clay model parameters were determined on the basis of the laboratory tests, and later, they were corrected by taking into consideration numerical analyses results (whole building and its parts) and real building settlements.

This paper presents the results of analysis of 100 full-scale scaffolding structures in terms of compliance with legal acts and safety of use. In 2016 and 2017, authors examined scaffolds in Poland located at buildings which were at construction or renovation stage. The basic elements affecting the safety of scaffolding use such as anchors, supports, platforms, guardrails and toe-boards have been taken into account. All of these elements were checked in each of considered scaffolding. Based on the analyzed scaffoldings, the most common errors concerning assembly process and use of scaffolding were collected. Legal acts on the scaffoldings are not always clear, and this causes many issues. In practice, people realize how dangerous the use of incomplete scaffolds is only when the accident occurs. Despite the fact that the scaffolding should ensure the safety of its users, most accidents on construction sites are caused by fall from a height., {"references":["J. C. Rubio-Romero, M. Carmen Rubio Gámez, and J. A. Carrillo-Castrillo, \"Analysis of the safety conditions of scaffolding on construction sites,\" Safety Science, vol. 55, pp. 160–164, 2013.","K. M. Halperin and M. McCann, \"An evaluation of scaffold safety at construction sites,\" Journal of Safety Research, vol. 35, pp. 141–150, 2004.","E. Błazik-Borowa and J. Szer, \"The analysis of the stages of scaffolding ''life'' with regard to the decrease in the hazard at building works,\" Archives of Civil and Mechanical Engineering, vol. 15, pp. 516-524, 2015.","S. M. Whitaker, R. J. Graves, M. James, and P. McCann, \"Safety with access scaffolds: Development of a prototype decision aid based on accident analysis,\" Journal of Safety Research, vol. 34, pp. 249–261, 2003.","Y.-L. Huang, W.-F. Chen, H.-J. Chen, T. Yen, Y.-G. Kao, and C.-Q. Lin, \"A monitoring method for scaffold-frame shoring systems for elevated concrete formwork,\" Computers and Structures, vol. 78, pp. 681–690, 2000.","M. Pieńko and E. Błazik-Borowa, \"Numerical analysis of load-bearing capacity of modular scaffolding nodes,\" Engineering Structures, vol. 48, pp. 1–9, 2013.","E. Błazik-Borowa, M. Pieńko, A. Robak, A. Borowa, and P. Jamińska-Gadomska, \"Analysis of ledger-stand joints in the aluminum modular scaffold,\" Archives of Civil Engineering, vol. 63, pp. 17–31, 2017.","A. Robak, M. Pieńko, and E. Błazik-Borowa, \"Examples of unusual construction scaffoldings used for renovation works of historic buildings,\" Civil And Environmental Engineering Reports, vol. 18, pp. 115–120, 2015.","M. Pieńko, A. Robak, and E. Błazik-Borowa, \"Scaffoldings used during the renovation of the Metropolitan Cathedral of St. John The Baptist and St. John The Evangelist in Lublin,\" Civil And Environmental Engineering Reports, vol. 19, pp. 79–86, 2015.\n[10]\tH. Irtaza, R. G. Beale, and M. H. R. Godley, \"A wind-tunnel investigation into the pressure distribution around sheet-clad scaffolds,\" Journal of Wind Engineering and Industrial Aerodynamics, vol. 103, pp. 86–95, 2012.\n[11]\tF. Yue, Y. Yuan, G. Li, K. Ye, Z. Chen, and Z. Wang, \"Wind Load on Integral-Lift Scaffolds for Tall Building Construction,\" Journal of Structural Engineering, vol. 131, pp. 816–824, 2005.\n[12]\tE. Błazik-Borowa and J. Gontarz \"The influence of the dimension and configuration of geometric imperfections on the static strength of a typical façade scaffolding,\" Archives of Civil and Mechanical Engineering, vol. 16, pp. 269-281, 2016.\n[13]\tJ. L. Peng, K. H. Chen, S. L. Chan, and W. T. Chen, \"Experimental and analytical studies on steel scaffolds under eccentric loads,\" Journal of Constructional Steel Research, vol. 65, pp. 422–435, 2009.\n[14]\tŁ. Borowski, M. Pieńko, P. Wielgos, \"Evaluation of inventory surveying of façade scaffolding conducted during ORKWIZ project,\" in Proceedings 2017 BGC Geodetic Congress, Gdansk, 2017, pp. 189-192. \n[15]\tT. Chandrangsu and K. J. R. Rasmussen, \"Investigation of geometric imperfections and joint stiffness of support scaffold systems,\" Journal of Constructional Steel Research, vol. 67, pp. 576–584, 2011.\n[16]\tT. Paczkowski and T. Wróblewski, \"The cause and circumstances of Bosta 70 scaffolding failure,\" in Proceedings XXV Conferences of Structural Failures, Miedzyzdroje, 2011, pp. 865-872."]}

The following paper presents numerical analyses and laboratory tests used for analyzing the impact of exploitation damage to the main structural members of the scaffolding frame system. The presence of inevitable defects reduces the strength of material compared to the theoretical strength. Numerical analysis preceded by own laboratory research allows you to describe precisely the behavior of the element. Performing a series of calculations gives information on the impact of the damage size and location on the bearing capacity of the scaffolding frame.

The paper presents an approach to evaluation of the dynamic wind action on scaffolding structures. FEM model of the scaffolding was created on the basis of geodetic measurements and verified by in-situ dynamic measurements of vibrations. Wind field, random in space and time, was simulated using Weighted Amplitude Wave Superposition (WAWS) method. Wind forces were applied to the nodes of the FEM model in every connection between stands and decks in outer plane of the scaffolding. Direct integration was used as the solution method. The time-dependent response of the structures was determined. Maximum response of the scaffolding was compared with results calculated according to the code recommendations.

This article describes three cases of scaffolding use as a structure for carrying out a renovation work at the Cathedral in Lublin. In order to achieve optimum access to the object, one used modular scaffolding. This type of scaffold is able to expand in any direction. In addition to the typical use, the scaffold was used as temporary roofing which allowed conducting the work during the winter. Monuments require a detailed approach to the problem of scaffolding. Despite the short period of use we should pay particular attention to the possibility of anchoring scaffoldings. Performing static calculation allows minimizing the number of anchors and used elements.

The paper is devoted to the problems of legal and technical making the ramp for disabled persons with scaffolds. Scaffolding system components allow you to assemble a structure that serve as the ramp and fulfil the requirements of technical conditions. From a legal point the most important is the fact that the ramp construction needs a building application. In this regard, the greatest problems is obtaining the rights to use the property for construction purposes. A big challenge is to also perform stress analysis, taking into account of dynamic impacts caused by the movement of the trolley. In this regard, the paper presents a numerical model of the ramp, static analysis, modal analysis and results of prediction of a disabled person ride on the trolley. The results of computer calculations have shown that the construction of the ramp requires the exact numerical analysis. Therefore, the best option would be in order to scaffolding companies will prepare relevant technical documentation of products which are ramps for the disabled.

Scaffolds are assembled from components. At the points where these elements connect, there are clearances causing inaccuracies of the structures and, as a result, imperfections. The paper presents a new method of making a geodesic inventory of scaffolding geometry. The method consists in measuring the mutual position of scaffolding points by means of tachymeters, and then determining the position of the points of connecting stands. Every step of the method, geodesic data processing and necessary calculations, are described in detail. Furthermore, histograms of local and global scaffolding imperfections are presented. The paper also comprises an analysis of measurement error. The method in question enables control of global imperfections immediately after the scaffolding is assembled and during construction works, which still poses a serious problem at construction sites. The realization of geometry measurements for 120 scaffoldings has proved the usefulness of the method, as well as the necessity to control the condition of a scaffolding in operation. In future, the results will be used in the process of the imperfection simulation in the numerical models of scaffoldings, to perform reliability analysis, to determine partial safety coefficients and, finally, in the process of their design.

The analyzes and classifications presented in the article were based on the research carried out in the years 2016 to 2018 on a group of over one hundred scaffoldings assembled and used on construction sites in different parts of Poland. During scaffolding selection process efforts were made to maintain diversification in terms of parameters such as scaffolding size, investment size, type of investment, location and nature of conducted 5works. This resulted in the research being carried out on scaffoldings used for church renovation in a small town or attached to the facades of classic apartment blocks, as well as on scaffoldings used during construction of skyscrapers or facilities of the largest power plants. This variety allows to formulate general conclusions about the technical condition of used frame scaffoldings. Exploitation damages of the frame scaffolding elements were divided into three groups. The first group includes damages to the main structural components, which reduce the strength of the scaffolding elements and hence the whole structure. The qualitative analysis of these damages was made based on numerical models that take into account the geometry of the damage and based on computational nonlinear static analyzes. The second group focuses on exploitation damages such as the lack of a pin on the guardrail bolt which may cause an imminent threat to people using scaffolding. These are local damages that do not affect the bearing capacity and stability of the whole structure but are very important for safe use. The last group consider damages that reduce only aesthetic values and do not have direct impact on bearing capacity and safety of use. Apart from qualitative analyzes the article will present quantitative analyzes showing how frequently given type of damage occurs.

The 21st century is a period of rapid development of computer technology, which allowed designers to create complex, three-dimensional models of engineering structures. Thanks to these solutions, it is possible to perform complex analyses, for example modal or dynamic ones of cable-stayed or suspension structures. For such objects, verification of the correct work of structural elements takes place in the field of non-linear analysis. The presented paper is an example of a comparative analysis concerning modal and static analysis - Natural Frequency with Nonlinear Material Models and Static Stress with Nonlinear Material Models, carried out in the Autodesk Simulation Multiphysics program with dynamic in situ tests of a suspension footbridge. The main purpose of the research was to evaluate the value of pre-tension forces in the cables of the load-bearing structure.

The paper presents data on natural frequencies and damping parameters of scaffoldings. The analyzes were made mainly on the basis of acceleration measurements made on scaffoldings on construction sites. These studies were supplemented by numerical analyzes, which allowed to show changing of the natural frequencies of the scaffoldings as the effect of the structure exploitation. Finally, it was found that the scaffoldings are structures with low natural frequencies ranging from 1.0 Hz to 4.0 Hz and a logarithmic decrement of damping at 0.06 in most cases, however differences can be observed with the values as low as 0.03.

The dynamic response of guyed masts models to the wind action in the wind tunnel was analyzed in the paper. Accelerations and forces in guys were measured. Spectra of the response were calculated. The influence of the wind structure on the response was analyzed. The results obtained from experiments were compared to the ones coming from a numerical analysis.

The paper is concerned with the numerical analysis of a node in modular scaffolds used for construction work. The purpose of this study is to determine the capacity of a node on the basis of the numerical analysis taking into consideration two factors: nonlinear material and the interaction between particular joint elements. The main subject of the analysis are the connections between the brace and the pipe and between the ledger and the pipe of the vertical standard. The result of the analysis is the maximum load that can be applied to the elements of the node. The numerical analysis is an alternative method over traditional methods involving laboratory research.

Measurements of the axial force variation in guys of mast model subjected to wind load of three different wind structures are presented in the paper. The measurements have been carried out in the wind tunnel of Wind Engineering Laboratory at Cracow University of Techn ology. The subjects of the research are two guyed masts of triangular and square shaft cross-sections. Mean values of forces and standard deviations as functions of wind parameters and wind attack angle have been calculated. Significant influence of wind structure on the forces in guys has been confirmed as the result. Additionally there has been noticed possibility of mast vibrations at critical velocities.

vol.15(2) (2016) 005-012, W artykule opisano problematykę związaną z rusztowaniami budowlanymi. Ze względu na traktowanie rusztowań jako konstrukcje podrzędne o małym znaczeniu często dochodzi do zaniedbań w jakości ich wykonania. Akty prawne, dotyczące rusztowań, nie zawsze są jednoznaczne, co rodzi wiele problemów. Pozornie niewielkie zmiany w schemacie statycznym, wynikające z konieczności dostosowania rusztowania do nieregularnych kształtów obiektu, mogą znacząco zmniejszyć nośność konstrukcji rusztowania. Każdy z obiektów budowlanych wymaga indywidualnego podejścia zarówno projektantów rusztowań jak i montażystów. Ponieważ rusztowania wykorzystywane jako tymczasowe zadaszenia i przekrycia umożliwiające przeprowadzenie prac wykończeniowych w czasie zimy nie są ujęte w katalogach każdorazowo konieczne jest opracowanie oddzielnej dokumentacji. Rusztowania są ustawiane w bezpośrednim sąsiedztwie istniejących lub wznoszonych obiektów i wymagają uwzględnienia infrastruktury wokół nich. Konieczne jest również prześledzenie procesu technologicznego w celu wyeliminowania możliwych kolizji rusztowania z innymi pracami wykonywanymi w obrębie obiektu., The paper deals with the practice versus scaffolding regulations. Due to a short period of scaffolding use, the quality of its performance is neglected. Legal acts of the scaffolding, are not always clear, which causes many problems. Minor changes to the static scheme, resulting from the need to adapt the scaffolding to irregular shapes of the object, can significantly reduce the load capacity of the scaffolding structure. Individual approach and direct cooperation are necessary of both fitters and designers during the assembly stage. Since the scaffolding used as temporary roofing for performing finishing work during the winter are not included in the catalogues and each time it is necessary to develop a separate document. Scaffolding is set directly at existing or constructed facilities and require to take all the infrastructure around it into account. It is also necessary to trace the technological process of work in order to eliminate possible overlapping of mutually exclusive processes.

The results of measurements of 2-D flow around rectangular prisms of square and rectangle cross-sections in wind tunnel are presented in this paper. The results include pressure and standard deviation distributions over the model walls, components of velocity vectors and statistical moments for fluctuations of the velocity in the wind tunnel measuring space. The arrangements of models and the range of measurements have been matched in order to the results could be used to the calibration of the numerical turbulence model and to the verification of computer calculations for the civil engineering problems. The values of parameters have been presented in graphs and subsequently used in a comparative analysis of the flows around both models.