This paper presents an experimental analysis of flexural capacity and deformability of structural concrete slabs prepared as composite members consisting of two concrete layers made of reinforced ordinary concrete (N) and fiber reinforced concrete (SFRC). The reinforced concrete composite slabs used in the tests were prepared in the dimensions of 600 x 1200 x 80 mm. The basis was composed of two layers consisting of SFRC, one as the top layer, and one as ordinary concrete. The results of the analysis confirm a significant improvement of structural properties of the composite slab in comparison to the slabs prepared wholly of ordinary concrete.
The progressive development of miniature systems increases the demand for miniature parts. Reducing the size of manufactured components on one hand is a serious challenge for traditional technologies, but on the other hand, mainly by removing the energy barrier opens the possibility of using other unconventional techniques. A good example is the ultrasonic excitation of the punch during the micro-upsetting process. The anti-barreling phenomenon and dependent on the amplitude of vibrations, intensive deformation of the surface layers in contact with the tools at both ends of the sample was noted. Based on the measured strains and stresses, an increase in temperature in the extreme layers to approx. 200°C was suggested. By adopting a simplified dynamic model of the test stand, the possibility of detaching the surface of the punch from the surface of the sample was demonstrated.
The paper is devoted to the strength analysis of a simply supported three layer beam. The sandwich beam consists of: two metal facings, the metal foam core and two binding layers between the faces and the core. In consequence, the beam is a five layer beam. The main goal of the study is to elaborate a mathematical model of this beam, analytical description and a solution of the three-point bending problem. The beam is subjected to a transverse load. The nonlinear hypothesis of the deformation of the cross section of the beam is formulated. Based on the principle of the stationary potential energy the system of four equations of equilibrium is derived. Then deflections and stresses are determined. The influence of the binding layers is considered. The results of the solutions of the bending problem analysis are shown in the tables and figures. The analytical model is verified numerically using the finite element analysis, as well as experimentally.
The paper presents the test description and results of thermal bowing of RC beams exposed to non-uniform heating at high temperature. Bending of a non-uniformly heated element is caused by free thermal elongation of the material it is made of. The higher the temperature gradient, the greater the bending. In the case when an element is exposed to load and high temperature simultaneously, apart from free bending also deformation of the RC element may occur, which is caused by the decrease of the concrete or reinforcing steel mechanical properties. In order to examine the contribution of the deflection caused by thermal bowing to the total deformation of the bent element with a heated tension zone, an experimental study of freely heated (unloaded) beams was performed. RC beams were heated: (1) on three sides of the cross-section or (2) only on the bottom side. Deflection of elements loaded by a substitute temperature gradient was calculated using the Maxwell-Mohr formula. The test results show that deflection of freely heated RC beams (caused by the thermal bowing phenomenon) can be 10 to 20% of the total deflection of loaded RC beams with a heated tension zone.
The main objective of this article is to obtain equations of motion of the spin–stabilized projectile in the presence of non–constant wind. Introducing models allowing utilization of inhomogeneous wind is dictated by new possibilities created by the use of e.g. lidars in the Fire Control Systems (FCS). Constant feed of wind data can replace meteorological messages, increasing the FCS effectiveness. Article contains results of projectile flight simulations which indicate the positive effect that the derived explicit form of the model has when considering software development for modern Fire Control Systems.
Experimental tests were carried out to assess the failure model of steel and basalt fiber reinforced concrete two-span beams. Experimental research was focused on observing the changes in behavior of tested elements in dependence on the ratio of shear reinforcement and type of fiber. The beams had varied stirrup spacing. The steel fiber content was 78.5 kg/m3 (1.0% by vol.) and basalt fiber content was 5.0 kg/m3 (0.19% by vol.). Concrete beams without fibers were also examined. Two-span beams with a cross-section of 120×300 mm and a length of 4150 mm were loaded in a five-point bending test. Shear or flexural capacity of tested members was recorded. The effectiveness of both sorts of fibers as shear reinforcement was assessed and the differences were discussed. It was shown that fibers control the cracking process and the values of deflections and strains. Fibers clearly enhance the shear capacity of reinforced concrete beams.
The most important challenges in the construction field is to do the experimentation of the designing at real time. It leads to the wastage of the materials and time consuming process. In this paper, an artificial neural network based model for the verification of sigma section characteristics like shear centre and deflection are designed and verified. The physical properties like weight, depth, flange, lip, outer web, thickness, and area to bring shear centre are used in the model. Similarly, weight, purlin centres with allowable loading of different values used in the model for deflection verification. The overall average error rate as 1.278 percent to the shear centre and 2.967 percent to the deflection are achieved by the model successfully. The proposed model will act as supportive tool to the steel roof constructors, engineers, and designers who are involved in construction as well as in the section fabricators industry.
The paper presents a method of structural monitoring with the use of angular displacement measurements performed with inclinometer devices. Inclinometer method is a solution free from the basic disadvantages of optical methods used commonly in structural monitoring, such as sensitivity to any type of visibility restrictions, pollution or influence of weather conditions. At the same time, with appropriate sensor parameters, a much better measurement accuracy is obtained than for typical optical methods and very low energy demand and moderate costs are achieved. Taking into account the above-mentioned issues, in the first stage an appropriate MEMS-type inclinometer sensor was selected, its laboratory tests were carried out and a method of the offset temperature drift correction, individual for each sensor, was developed.
The article presents the results of non-destructive testing and analyses carried out for a brick masonry building from the 19th century, which has many irregularities that involve a lack of inspections and tests of its technical condition for many years, as well as a failure to carry out necessary repairs. The conducted organoleptic tests enabled the most significant building damage to be indicated, and its causes were determined on the basis of the results of non-destructive tests and analyses. These causes include mainly wall cracks, ceiling deflections and excessive dampness. It also contains the relationships, which were developed using non-destructive dielectric and resistive methods when testing the moisture content of the brick walls. These results may be useful for other researchers dealing with brick masonry buildings from a similar period of time. The authors' intention was to present the existing poor technical condition of the brick masonry building and indicate its causes, as well as to present that a lack of appropriate maintenance can lead to a situation in which the life or health of residents is threatened.
The paper presents a method of structural monitoring with the use of angular and linear displacement measurements performed using inclinometer and laser measuring devices. The focus is mainly on the inclinometer measurement method, which is a solution free from the basic disadvantages of optical methods, such as sensitivity to any type of visibility restrictions, pollution or influence of weather conditions. Testing of this method was carried out in practical application in an wireless monitoring system, installed in a large-area industrial building. The measurement results performed using the inclinometers were compared with simultaneous measurements of linear displacements performed with the use of proven methods based on laser rangefinders. The research and analysis show that the method of measuring angular displacements using the inclinometers with MEMS sensors of appropriate quality is a very good, better than typical optical methods, solution of structural monitoring systems that allows to obtain accurate and reliable results.