The repairs of building structures are inevitable and indispensable. Repairs are used to restore or maintain the usability of existing facilities, often contributing to the extension of their ...expected service life, increasing the sustainability of building resources. Given that conservation rules are observed, repairs are also used to save monuments. The concept of repair durability brings to the foreground the durability of the repaired structure (after repair): what service life has been obtained/recovered as a result of the repair. Based on the available data (limited set), a generalised distribution function of repair durability was developed, with a disappointing course. This, however, applies (necessarily) to the past. Significant progress was shown to have been achieved in the theoretical and technical fundamentals of technical repair measures. In this situation, a prognostic distribution function was also designed for future repairs according to EN 1504. A rule of thumb called estimating concrete repair durability, CRD was proposed. The risk associated with estimating the durability of repairs was indicated. A reason for optimism is that proactive monitoring of the condition of the structure and, consequently, management of the repair strategy allows to reach the designed life of the structure.
The research paper presents a novel approach toward constructing motion equations for structures with attached MTMDs (multiple tuned mass dampers). A primary system with MDOF (multiple dynamic ...degrees of freedom) was reduced to an equivalent system with a SDOF (single degree of freedom) through the modal approach, and equations from additional MTMDs were added to a thus-created system. Optimization based on ℌ2 and ℌ∞ for the transfer function associated with the generalized displacement of an SDOF system was applied. The research work utilized GA (genetic algorithms) and SA (simulated annealing method) optimization algorithms to determine the stiffness and damping parameters for individual TMDs. The effect of damping and stiffness (MTMD tuning) distribution depending on the number of TMDs was also analyzed. The paper also reviews the impact of primary system mass change on the efficiency of optimized MTMDs, as well as confirms the results of other authors involving greater MTMD effectiveness relative to a single TMD.
In the paper there was analyzed a mechanism of loss of performance properties of inverted roof insulation kits resulted by moisture increase of the insulation layers. This problem is very important ...in such systems because the thermal insulation is placed above the waterproofing layer and is not protected against water absorption. Abovementioned problem is more and more common in the course of building’s utilization in Polish climate conditions. Because inverted roof kits are based on extruded polystyrene (XPS) and expanded polystyrene (EPS), those materials have been used in tested samples. The results of laboratory tests showed the phenomenon and its effect on durability and sustainability of roof covering performance. It was also found that the biggest influence on the increase of moisture in the thermal insulation layer has not the long term water absorption by immersion but freeze –thaw cycles.
External thermal insulation systems (ETICS) are relevant facade applications of functional components allowing to reduce energy consumption in buildings to fulfill the provisions of nearly ...Zero-Energy Buildings (nZEBs). ETICS systems generally are made of adhesives, thermal insulation material, renders with mesh reinforcement, primers, and finish coats. Their main parameters are thermal characteristics and durability, both determined by the specific composition of the systems. Growing concerns on the environment and depletion of natural resources drive the need for the determination of the environmental characteristic of ETICS due to its growing market demand. This analysis focuses on a life cycle assessment (LCA) of a commonly used EPS based ETICS system with four different renderings, produced in several locations. The scope of this study concerns raw materials extraction, transport, production, and energy provision up to the finished, packed, and ready-for-sale product at the factory gate. The authors compared the environmental impact allocated to the 1 m2 of the produced system by taking into account the thickness of EPS and within different environmental impact categories. The results of the current impacts were compared to those obtained five years earlier, considering the technological and environmental progress of the production process.
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•The method for assessing the technical conditions of scaffolds used on construction sites.•Inventory of scaffolds and full-scale measurements of their loads.•Finite elements static ...analyses of scaffolds which are subjected to real loads.•Scenarios of scaffolding failures.•The probability of a scaffold failure at maximum loads.
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.
Analysis of the construction market in Poland and its trends in the recent years indicates a resurgence of prefabricated technology in residential construction. The main period of prefabrication ...development in Poland was in the 1970s. when it was referred to as large panel. According to a report by Building Research Institute, buildings constructed with large panels are characteristics for their high durability and any damage occurring in the buildings built using the technology can be divided into two groups. The first is damage similar to that occurring in traditional construction, such as damage to partition walls, roof covering or installations. The other is damage related to the prefabrication technology itself, i.e. the production of elements (material damage) and their assembly (damage at connections). Other potential threats include mining activity in the case of buildings located in mining areas and gas explosions related to the gas systems present in this type of building. This paper, therefore, attempts to recreate the process and consequences of an explosion in a closed room of a multi-family building using a numerical model. The simulations are based on: literature data (concerning calculating and applying explosion actions) and own experience in assessing the response of a concrete structure described using an elastic-plastic-damage (e-p-d) model. The result of the analyses included indication of areas directly affected by risk of loss of stability (with potential expansion of disaster area). The paper also presents the effect of "expulsion" of an external wall due to explosion. It was found that structure failure states obtained in the analyses are fully compatible in qualitative sense with observed real construction disasters caused by explosions. Real quantitative trustworthiness should result from laboratory tests of materials from which the buildings under analysis are built of.
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