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Abstract

In the case of light structures membrane type the form is confused with the structure and vice versa. Thus the analysis process, non-linear type, the one for form finding is also a means of optimizing these structures. To respect the natural principle of minimum it is advisable that the structure’s shape is similar to the minimum surface area. The numerical problem solving is based on using finite elements with constant strain of soap film. Based on these considerations, the paper presents aspects of determining the shape of the membrane structure using finite elements of soap film.

Abstract

Intended contribution emphasizes the statics and kinematics of semi-rigid steel frames seismically acted upon. The dynamic model of analyzed structures consists of multi degree of freedom systems with lumped masses located at floor levels. The dynamic degrees of freedom are the lateral seismically induced floor displacements. A cyclic behavior of semi-rigid beam – column connections associated with the four parameters analytical bending moment M – relative rotation θr is considered. Time history seismic analyses are performed on multi-story steel planar frames equipped with several top and seat and web angle beam – column connections acted upon by recorded seismic actions. The computed numerical results refer to the contrary static and effects of semi-rigidity: the increase in lateral floor displacements accompanied by a decrease in the seismic base shear force. Relevant comments are drawn.

Abstract

The paper presents the results of numerical analysis on the effects of thermal bridges at wood frame buildings with or without thermal insulation placed on the exterior surface of the wall. The heat flow crossing the wooden thermal bridges, respectively the linear heat transfer coefficients ψ and the temperature factors fRsi, can be established based on the plane temperature field in stationary thermal regime. The “PSIPLAN” computer program used to determine the temperature field, derived from the original program “CIMPLAN” with its first version developed in 1980. The program allows graphic description of the plane section of a thermal bridge and discretizes automatically the section on both axes in accordance with the stipulations of the EN ISO 10211-1:1995 standard and EN ISO 10211:2007 standard. The computer program generates automatically the system of equations that is solved using iterative methods until the heat flows on the two surfaces of the section are balanced. The calculation results are presented with numerical values and in a graphical manner by isothermal surfaces. The program has various libraries that include several types of wood thermal bridges.

Abstract

Due to development of GPS technology and by using the combination LC of L1 and L2 frequency the first order effect of the ionosphere tends to be canceled. Thus the main source of errors in the atmosphere which causes the delay in GPS signal is the neutral part of the atmosphere, usually referred to tropospheric delay. In general, the delay is computed at the zenith direction and it is referred to zenith tropospheric delay. The zenith tropospheric delay consist of two parts: zenith hydrostatic delay and zenith wet delay. The zenith hydrostatic delay can be very well modeled which accounts for nearly 90% to 100% of the atmospheric delay. The zenith wet delay is due to the water vapor and represents the “harder” part that need to be modeled caused by “unmixed” condition of the wet atmosphere. The influence of the zenith wet delay is around 0-40 cm. The aim of the article is to present the results obtain on the network of three station which were spread around the Oradea city using different types of mapping functions. The mapping functions are: global pressure and temperature – GPT2 and Vienna mapping function – VMF1. For the vertical studies to obtain the highest accuracy, the recommended mapping function is VMF1.

Abstract

The goals of this paper are: to estimate the carbon emission reduction on energy efficiency measurements in a laboratory building in Transilvania University from Braşov, Romania, in accordance with the European Directive 2009/28/EC and to estimate the contribution of renewable energy to energy efficiency of the building using the performance indicator named Renewable Energy Ratio - RER. We will detail the methods of calculation for CO2 emissions and we will present the results for gas condensing boiler, and ground source heat pump for the laboratory building. The results show that conventional energy efficiency technologies and renewable energy technologies can be used to decrease CO2 emissions in buildings by 20–30% on average and up to over 40% for some building types and locations. The contribution of renewable energy is between 40 and 50 % from total energy use and only for heating is 58%. This value could rise to 0.63 if we apply to electricity produced by photovoltaic panels.

Abstract

Because of the dynamics of the GPS technique used in different domains like geodesy, near real-time GPS meteorology, geodynamics, the precise point positioning (PPP) becomes more than a powerful method for determining the position, or the delay caused by the atmosphere. The main idea of this method is that we need only one receiver – preferably that have dual frequencies pseudorange and carrier-phase capabilities – to obtain the position. Because we are using only one receiver the majority of the residuals that are eliminated in double differencing method, we have to estimate them in PPP. The development of the PPP method allows us, to use precise satellite clock estimates, and precise orbits, resulting in a much more efficient way to deal with the disadvantages of this technique, like slow convergence time, or ambiguity resolution. Because this two problem are correlated, to achieve fast convergence we need to resolve the problem of ambiguity resolution. But the accuracy of the PPP results are directly influenced by presence of the uncalibrated phase delays (UPD) originating in the receivers and satellites. In this article we present the GPS errors and biases, the zenith wet delay and the necessary time for obtaining the convergence. The necessary correction are downloaded by using the IGS service.

Abstract

The paper presents a simplified calculation method to predict, as accurate as possible, the most important characteristics of the behaviour of the slender reinforced concrete shear walls in the inelastic range: failure mode, strength capacity, flexural and shear deformations, sectional and element ductility. The formulation is based on nonlinear beam element with taking into account the influence of shear, both on strength and stiffness of the wall. The principal parameters incorporated in the calculation model are: the rectangular shape of the cross section, the aspect ratio of the wall, the most accurate constitutive relationships for the compressed concrete and for the reinforcement steel, both in compression and in tension (including the strengthening of the steel after yielding), the variation of the Poisson ratio of the concrete, the amount and distribution of the vertical reinforcement. The model uses the concept of distributed (smeared) plasticity along the element and so the flexural deformations are computed by integrating the actual curvatures on the height of the wall. The shear deformations are also calculated, in agreement with the results of some recent experimental researches. The calculation method was then applied to two experimental wall specimens and their force – horizontal top displacement curves were plotted.

Abstract

In designing artwork as bridges, hydraulic calculations have a very important role due to the fact that they are behind their sizing. Bridge designer must therefore possess knowledge of hydrology, hydraulics of bridges and river banks regularization. A problem that arises during the design stage of bridges is the scour phenomenon surrounding bridge pier. Over time, there have been conducted a number of studies which led to the provision of a plurality of mathematical models that are intended scour prediction. In the present article we will present an experimental study to determine the bed profile and measurement of scours products around a pier bridge using 3D terrestrial laser scanner.

Abstract

Energy efficient design is a high priority in the national energy strategy of European countries considering the latest requirements of the European Directive on the Energy Performance of Buildings. The residential sector is responsible for a significant quantity of energy consumptions from the total amount of consumptions on a worldwide level. In residential building most of the energy consumptions are given mainly by heating, domestic hot water and lighting. Retrofitting the existing building stock offers great opportunities for reducing global energy consumptions and greenhouse gas emissions. The first part of the paper will address the need of thermal and energy retrofit of existing buildings. The second part will provide an overview on how various variables can influence the energy performance of a building that is placed in all four climatic zones from Romania. The paper is useful for specialist and designers from the construction field in understanding that buildings behave differently from the energy point of view in different climatic regions, even if the building characteristic remain the same.