Applied Mechanics and Materials Vol. 796

Abstract: The effectiveness of egress paths from a building could be attributed to good signage or intuitive Architecture but we know it is also influenced by human behaviour in fire. The extent to which human behaviour plays a role in the effectiveness of egress routes is not yet fully understood.The aim of this paper is to investigate human behaviour in a relatively simple study of exit choice. The study is conducted in a virtual environment by examining the effectiveness of additional floor-based chevron arrows when compared with conventional exit signage on the same escape routes.Fifty nine participants were asked to interact with the software to escape from a fire in the created virtual environment. Thirty two of the participants used a model with conventional exit signs only. Twenty seven of the participants used the model with exit signs and chevrons on the floor. After completing the virtual egress exercise the participants were given a questionnaire to help understand their behaviour during the task. This allowed the authors to compare results of the post experiment questionnaire with the video output of the test.This research is novel in that involves the use of already existing technologies for new purposes; in this case, commercial computer games engines, generally used for entertainment purposes. As technology reaches new levels it is inevitable that there will be overlap in functionality.This paper describes the experiments, analyses the information gleaned from the research and provides some conclusions for consideration by others in this field. By assessing exit choice behaviour and evacuation time it is possible to compare the effectiveness of the additional floor based signage as a fire protection measure provided above and beyond normal code requirements.

Abstract: In this paper the behaviour of old floors made up of wrought iron beams supporting shallow masonry vaults is analysed. The performance of this structural system, which was extensively used in Europe in the XIX century, has been only marginally investigated thus far. Very few studies on masonry-iron composite floors are available in the literature, where the role played by the physical interaction between the vaults and the metallic profiles has yet to be fully understood. When assessing historical buildings with floors characterised by the analysed floor system, a realistic estimate of this interaction may be critical to avoid unnecessary and costly strengthening works. The floor structure with composite wrought iron beams and solid brick vaults of the “Military Hospital” in Trieste built in 1840 by the Hapsburg Military Administration have been investigated performing physical experiments and numerical simulations. Experimental tests were carried on the floor and used to calibrate finite element numerical descriptions. These have been adopted in numerical simulations to investigate the response of the analysed floor system up to collapse considering different geometrical characteristics for the floor. The numerical results shed some light on the actual interaction between the different components of the composite floor which significantly influences the floor stiffness and load bearing capacity.

Abstract: High traffic load and high temperatures are two crucial aspects, which cause together with static treatment of transport, respectively slow traffic, permanent deformations in the construction of flexible pavement (the cover layer of asphalt). Standard asphalt adjustments are not able to withstand such loads. For these reasons they are looking at ways to increase the functionality of asphalt mixtures and extend their lifespan, respectively delay condition, where it is not possible to use it comfortably. On the road is necessary to look at the whole life cycle and give priority in justified cases to demanding investment solutions, which thanks to longer durability and longer repair cycle will be cheaper. Such solutions are composite materials based on asphalt. Among them are technology of asphalt and cement composite (ACC), which uses strengths of both used materials, or by analogy with the principle of concrete reinforcement in asphalt mixtures. This article presents the characteristics of both technologies, their properties and points to the longer life of the construction of roads in their application.

Abstract: Different types of composite materials with potential application in ballistic protection of static objects are discussed and compared in present study. The studied solutions include: 1) the concretes with or without reinforcement, 2) the metallic boxes with internal gap filled with different materials and 3) the ceramics-metallic composite armours. Besides the ballistic resistance, the areal weight and the price are taken into account. The weight of solutions is important in case of static objects mainly from logistic point of view. The proposals of ballistic compositions presented in the study can facilitate the choice of solutions according to specific requests.

Abstract: This paper presents design solutions to occupational safety and health agenda (OSH) using a computer directly. It connects this agenda directly to the automated construction technology design and to the process of construction planning. It describes the first results the authors obtained as well as the draft register of occupational safety and health risks and their database that shall be used for automated production of OSH plans. Furthermore this paper describes a draft program for the creation of plans and schedules of OSH risk inspections, a program for OHS inspections and operational records of them as they are carried out. All this is in direct relation to a computer system for construction technology designing that is used in order to model building construction via implementing the construction technology network diagram method.

Abstract: The reduction of seismic vulnerability of existing masonry buildings through the application on the walls of a mortar coating reinforced with a GFRP (glass fiber reinforced polymer) mesh is studied and discussed. Numerous experimental tests, carried out by the authors, demonstrate the effectiveness of this technique for enhancing the mechanical response of the walls, both subjected to in-plane and out-of-plane actions. In the study, the capacity curves of an existing unreinforced masonry building are compared with those of the same building strengthened with the GFRP reinforced mortar coating technique. An almost regular two storey building is considered in the numerical study and it is analyzed by adopting the method of the equivalent frame. Two different types of masonry are considered in the study: solid bricks and rubble stones. Static nonlinear analyses are carried out and the nonlinearity of the material of the wall elements (piers and spandrels) is considered through the introduction of plastic hinges in the plane of the masonry wall. The results evidence a significant increase in terms of shear resistance, displacement capacity and total strain energy. The collapse due to bending of piers in most cases of strengthened buildings occurred before than the ultimate shear drift was obtained.

Abstract: Due to increase of requirements on accuracy of structural analyses, practically applicable computational tools for reliable determination of the real structural performance of bridges are needed. A method is proposed for the true full 3D analysis which can be applied to achieve the real spatial behaviour of concrete bridge structures taking into account rheological phenomena and changes of structural systems. Particularly, the effects of shear lag, shear performance of webs of box girders, warping torsion, warping of cross-sections, distortional effects, state of stresses in the singular regions, the real prestress loss, etc., can be correctly determined. The method combines conventional approaches (based on the elementary beamtype assumptions) for calculating the time development of the internal forces due to rheological phenomena and changes in the structural system during construction and routine commercial FEM software intended for calculating spatial shell structures. The method is capable to give the true 3D prediction of structure behaviour by using only commercially available software. The primary advantage of the proposed method is its ease of application which allows the true 3D performance to be determined from simple calculations. The method offers the designers of concrete bridge girders an ideal design tool. The correct 3D simulation can lead to more efficient and economical designs.

Abstract: With the increase in acts of terrorism, the effects of the explosion on structures has become highly topical. The aim of the paper is an analysis of various approaches to determine the response of blast loaded reinforced concrete pillar. Homemade ANFO (Ammonium nitrate + fuel oil) explosive will be a reference explosive. Such type of explosives is the most used one in terroristic attacks. The paper will be focused on the analysis of the blast wave, based on the experimental tests, and dynamic analysis of a structure under such load.

Abstract: The leaching behavior of hydraulic concrete can’t be neglected for its long-term exposure to surrounding water resulting in irreversible damage to durability, such as strength loss and porosity increase. Given that the coupling effect of leaching and freeze-thaw cycling on the durability of hydraulic concrete especially in severe cold regions is a big challenge. For the quite slow process of natural leaching, electrochemical accelerated leaching method (EALM) was proposed to investigate the damage evolution under two test schemes (scheme one is only leaching for 50 days and scheme two is first 100 rapid freeze-thaw cycles and then leaching for 50 days) designed in this work. The electrical resistivity and calcium oxide dissolution mass were measured through electrochemical impedance spectroscopy (EIS), namely two-probe method, and EDTA titration method, respectively. Based on electrical resistivity measurement, the measurable damage can be discussed during abovementioned singe and coupled tests. The results indicate that compared with single leaching test, the leaching coupled with the freeze-thaw cycling leads to over 50% electrical resistance loss.