Martins Vilnitis

The authors propose a handgun bulletproof load-bearing 140 mm cross-laminated timber (CLT) wall with knitted aramid (Kevlar) fabric in two layers for tangling the bullet and a reference wall without a Kevlar layer. The study compares the layers in which the added aramid sheet should be placed for northern areas to allow people to have acceptable insulated conditions in temporary houses while being protected from potential bullet external threats. Results showed that a 140 mm CLT layer with 200 mm mineral wool insulation with a Kevlar layer between the insulation layer and CLT is enough to stop the bullet if fired up to 341.6 m/s with a firearm. Perforation data for CLT material samples with various thicknesses have been collected and analyzed. A metal rod and a ruler determined the penetration depth for ogive-nose projectiles when they did not fully perforate the panel. The results show the ballistic properties of CLT material. The results will be proposed to the construction industry of wooden buildings as a bonus for those whose security is significant.

With the growing popularity of timber structures, the requirement for reliable and non-destructive methods to assess the quality and condition of structural joints becomes increasingly essential. A novel coaxial correlations method is investigated to assess the degradation of panel-to-panel moment joints in timber structures. The method involves analysing the response data obtained from accelerometers placed on both sides of the joint and comparing the readings to evaluate the joint’s condition. A specific joint solution to simulate the degradation of the moment joint in laboratory conditions is selected based on its simplicity and the ease with which its degradation can be simulated. The joint consists of angle brackets joined with timber screws and bolts to plywood panels. Gradually unscrewing the timber screws reduces the joint’s stiffness to simulate wear and tear over time. The experimental setup includes static loading and finite element modelling (FEM) to determine the rotational stiffness of the investigated joint at each degradation level. A dynamic experiment using vibration loading with sweep signal in the frequency range of 10 Hz to 2000 Hz is conducted to assess the quality of the joint. The conducted research provides valuable insights into the behaviour of timber panel-to-panel connections. The findings highlight the relationship between joint stiffness, vertical displacements, and the proposed dimensionless parameter, volume root mean square value (RMS_vol), which offers a more comprehensive assessment of the joint’s condition in three spatial directions. As a result of the research, it has been established that, in the case of linear-type connections, unlike point-type joints, there is a possibility of signal scattering, so it is recommended that power comparisons and evaluations of the response signals from both accelerometers at the initial stage of applying the coaxial correlations method are performed.

In this study, bullet-proof building panels are investigated. The aim of this work is to verify whether the polyethylene-plywood panels withstand frontal impact with high-speed projectiles. Ultra-high molecular weight polyethylene (UHMWPE) is a promising ballistic material due to its favorable properties – significant impact toughness and a high strength-to-weight ratio, meantime it is lightweight. By setting different parameters such as laminated plywood width and various UWHMPE facade layers, the protective effect of the panels and their performance characteristics are discussed using a 9 mm caliber handgun Glock 17 Luger bullets. The results show positive results – 3 of 4 combinations resist the bullet. The board with an arrangement of 2x32 cm laminated plywood outside and UHMWPE material inside the room captures 4 bullets; the bullets pass through the plywood layer and stop in the polyethylene. The experiment also tested individual UHMWPE panels at 2 different thicknesses to monitor the damage to the material. The results of this study will be useful in designing ballistic panels for buildings like unclassified buildings (army headquarters, safe rooms) from small arms weapons also for individual use.

The accumulation of the radioactive gas radon in closed environments, such as dwellings, is the result of a quite complex set of processes related to the contribution of different sources. As it undergoes different physical mechanisms, all occurring at the same time, models describing the general dynamic turns out to be difficult to apply because of the dependence on many parameters not easy to measure or calculate. In this context, the authors developed, in a previous work, a simplified approach based on the combination of a physics-mathematical model and on-site experimental measurements. Three experimental studies were performed in order to preliminarily test the goodness of the model to simulate indoor radon concentrations in closed environments. In this paper, an application on a new experimental site was realized in order to evaluate the adaptability of the model to different house typologies and environmental contexts. Radon activity measurements were performed using a portable radon detector and results, showing again good performance of the model. Results are discussed and future efforts are outlined for the refining and implementation of the model into software.

Among the physical pollutants affecting indoor air, the radioactive gas radon may turn out to be the most hazardous. Health effects related to radon exposure have been investigated for several decades, providing major scientific evidence to conclude that chronic exposures can cause lung cancer. Additionally, an association with other diseases, such as leukemia and cancers of the extra-thoracic airways, has been advanced. The implementation of a strategy to reduce the exposure of the population and minimize the health risk, according to the European Directive 59/2013/Euratom on ionizing radiations, is a new challenge in public health management. Starting from an understanding of the general state-of-the-art, a critical analysis of existing approaches has been conducted, identifying strengths and weaknesses. Then, a strategy for assessing the radon exposure of the general population, in a new comprehensive way, is proposed. It identifies three main areas of intervention and provides a list of hazard indicators and operative solutions to control human exposure. The strategy has been conceived to provide a supporting tool to authorities in the introduction of effective measures to assess population health risks due to radon exposure.

The proposed paper examines the success indicators of sustainable construction projects, and its relationship to building codes with specific focus on safety, quality and budget aspects in terms of their implications and impacts prior, during and after construction. Such a research will be very beneficial to the construction industry and the government of all countries in terms of significant money savings and preservation of national wealth and resources through sustainable construction approaches. Consideration of sustainability at the design stage is emphasized. Building safety and the roles of building codes in prevention of structural failures are also covered in the paper together with factors affecting building failures and methods for their prevention in early design phases. Construction process is introduced in the paper from the perspective of modern total quality management. Concepts of quality management, quality control, quality assurance and six sigma and how they relate to building sustainability are discussed with examples. At least the importance of appropriate maintenance of building during expected life time are partly covered in the paper. It was necessary, in an initial stage, to define the key indicators that should be considered in order to assess the main aspects of sustainable construction. This paper intends to present the analysis that was performed in order to select some of quality evaluation indicators.

This paper examines the success indicators of construction projects, safety, quality and productivity, in terms of their implications and impacts during and after construction. First safety is considered during construction with a focus on hazard identification and the prevention of occupational accidents and injuries on worksites. The legislation mandating safety programs, training and compliance with safety standards is presented and discussed. Consideration of safety at the design stage is emphasized. Building safety and the roles of building codes in prevention of structural failures are also covered in the paper together with factors affecting building failures and methods for their prevention. Quality is introduced in the paper from the perspective of modern total quality management. Concepts of quality management, quality control, quality assurance and Six Sigma and how they relate to building quality and structural integrity are discussed with examples. Finally, productivity concepts are presented with emphasis on effective project management to minimize loss of productivity, complimented by lean construction and lean Six Sigma principles. The paper concludes by synthesizing the relationships between safety, quality and productivity.