BRJ – Volume 57, Number 3–4, 2009
Building Research Journal
Volume 57, Number 3 – 4, 2009
Jan Sladek, Vladimir Sladek and Peter Solek:
Traansient Thermoelastic Analysis of Piecewise Homogeneous 3D Solids by the MLPG Metod . . . 131 – 151
Břetislav Teplý and Dita Vořechovská:
Performance-Based Design of ConcreteStructures: Parametric Approach . . . 153 – 167
Alexander Tesar and Jozef Lago:
Aeolic and Galloping vibrations of Overhead Lineco Nductors . . . 169 – 183
Himat H. Ali and Saba F. Al Nsairat:
Comparative Analysis of Green Building Assessment Tools: Leed, Casbee, Breeam and GB Tool . . . 185 – 198
Andrej Jarosevic, Milan Chandoga and Alexander Tesar:
Utilizing EM Sensor in Dynamic Mode for Percussive Load Measurement . . . 199 – 222
Vladimír Živica, Ľubomír Bágeľ and Božena Vasilkovová:
Borehole Cements and Composites for the Exploitation of Geothermal Energy . . . 223 – 231
Boris Bielek, Milan Bielek, Daniel Szabó:
Natural Physical Cavity Regime of Double-skin Facade in Windless Climate Conditions
– Long Term Experiment In-Situ . . . 233 – 246
Determination of Air Permeability of Low Energy Building by in Situ Measurement . . . 247 –257
Traansient Thermoelastic Analysis of Piecewise Homogeneous 3D Solids by the MLPG Metod
Jan Sladek, Vladimir Sladek and Peter Solek
The meshless local Petrov-Galerkin (ML PG) method for transient linear thermoelastic analysis is presented. Anisotropic material with piecewise homogeneous properties is considered here. In uncoupled thermoelasticity, the temperature field is not influenced by displacements. Therefore, in the first step, the heat conduction equation is solved for the temperature distribution in the domain. The equations of motion are then solved with the inertial term considered. A Heaviside step function as the test functions is applied in the weak-form to derive local integral equations for solving three-dimensional problems. Local integral equations are written on small sub-domains with spherical shapes. They surround nodal points which are distributed over the analyzed domain. The spatial variation of the displacements and temperature are approximated by the moving least-squares (MLS ) scheme. After performing the spatial integrations, a system of ordinary differential equations for certain nodal unknowns is obtained. The backward finite difference method and the Houbolt finite-difference scheme as time stepping methods are applied to solve the system of ordinary differential equations.
Keyword: Transient thermoelasticity, anisotropic materials, moving least-squares interpolation, Houbolt finite-difference scheme
Performance-Based Design of ConcreteStructures: Parametric Approach
Břetislav Teplý and Dita Vořechovská
Performance-Based Design (PBD ) is becoming a leading trend in structural engineering design and deals with durability and reliability issues, which are the most decisive structural performance characteristics. Thus, when designing reinforced concrete structures, relevant durability limit states have to be assessed focusing on an appropriate level of reliability. Concentrating on those types of performance, a review of durability limit states and PBD methods focused on concrete structures is provided. The application of fully probabilistic PBD with the utilization of the parametric approach is presented in the paper together with useful software tools. Three illustrative examples are included showing some of the possibilities of PBD in practice: (i) the effect of concrete cover on service life considering the carbonation of concrete, (ii) relations among CO 2 emissions, fly ash content, economical consequences and reliability, and finally, (iii) crack development in concrete cover due to reinforcement corrosion.
Keywords: Performance Based Design, concrete structures, degradation modelling, durability, service life
Aeolic and Galloping vibrations of Overhead Lineco Nductors
Alexander Tesar and Jozef Lago
The present paper deals with an analysis of aeolic and galloping vibrations of overhead high voltage line conductors subjected to the action of wind. On the basis of theoretical approaches submitted there are developed numerical algorithms and models for analysis of the above kinds of vibration. Taking into account the actual forcing for initiation of ultimate structural response in aeolic and galloping vibrations there are made the assessments for specification of optimal numbers and distances of Stockbridge dampers, adopted as tuned vibration control elements in the overhead lines of high voltage conductors. Some results with discussion and conclusions are submitted.
Keywords: aeolic vibration, galloping, nonlinearities, overhead line conductors, Stockbridge dampers, ultimate behaviour, wave approach
Comparative Analysis of Green Building Assessment Tools: Leed, Casbee, Breeam and GB Tool
Himat H. Ali and Saba F. Al Nsairat
Assessment tools were the first approaches which were introduced for measuring and reporting sustainability of performance of a building. The building sector has witnessed the development of two types of assessment tools. The first type includes the tools, which are purely based on a criteria system. The second type includes the tools that use a life cycle assessment (LCA ) methodology. The purpose of this research aimed at studying, analyzing, evaluating and comparing the most green building rating systems (LEED , CASBEE , BREEAM , and GB Tool). The study showed major differences among the different systems. GB Tool does not include operating & maintenance of projects. Nevertheless, LEED works to develop a program for urban level according to the perception of the US market. However, LEED programs are considered the most fairly comprehensive in scope – from landscaping to renewable energy to recycling building materials.
Keywords: green building, assessment tools
Utilizing EM Sensor in Dynamic Mode for Percussive Load Measurement
Andrej Jarosevic, Milan Chandoga and Alexander Tesar
Corrosion monitoring of the cables supporting the New Bridge crossing Danube in Bratislava. The monitoring is made in scope of dynamic testing of the bridge. The development and utilization of the EM sensor package for present purpose. Assessment and evaluation of the results obtained.
Keywords: bridge, cables, corrosion monitoring, dynamic testing, EM sensor, frequencies, magnetic field, magnetizing coil
Borehole Cements and Composites for the Exploitation of Geothermal Energy
Vladimír Živica, Ľubomír Bágeľ and Božena Vasilkovová
The continual increasing of energy consumption makes for searching and using alternative kinds of energy. Geothermal energy has a great potential because of its availability, independence of seasons and minimal environmental impact. The heat obtained from 7 to 10 km deep boreholes could be an interesting source of energy used for making electricity. The deep geothermy needs effective drilling technologies and their development is a significant precondition of exploitation of geothermal heat. The application of cement composite materials is an important part of drilling construction. During the application the fresh composites mixtures are exposed to the increase of the ambient temperature and pressure – from atmospheric to the level given by the bore deep. The similar conditions act on the material of the cement composites during the exploitation of the drilling construction. Moreover the action of high aggressive environment is usually current. All these conditions represent high demands not only on the properties of cement composites mixtures and their constituents, but even on the application technology. Therefore, a design of the correct composition needs to have the fundamental theoretical and research knowledge dealing with the relations between the properties of the fresh and hardened composites and the conditions in the borehole. An adequate proposal of the cement composites composition is a goal of the project supported by the European Regional Development Fund (ERD F).
Keywords: geothermal heat bore technology, cement composites, setting, hardening, properties, temperature, pressure, aggressivity
Natural Physical Cavity Regime of Double-skin Facade in Windless Climate Conditions – Long Term Experiment In-Situ
Boris Bielek, Milan Bielek, Daniel Szabó
A double-skin transparent facade performance of the National Bank of Slovakia building in Bratislava was investigated. A natural physical cavity and its parameters were quantified in-situ. The measuring technology was described and an example of the results of the climate-dependent processing was given. The partial results of the experiment from a critical summer period were documented. The theory of natural physical cavities and its application references were presented. The theory was verified by application of in-situ experiment. Experimental research of convective air flow through natural physical cavity of corridor type with a year-round open circuit and with alternating air inlet and outlet modules was carried out. Specifics of convective air flow in natural cavity – new knowledge. The paper represents the confrontation of theory and experiment, including scientific polemics on the new knowledge.
Keywords: double-skin transparent facade, natural physical cavity, experiment insitu, climate-dependent process – problem, convective air flow
Determination of Air Permeability of Low Energy Building by in Situ Measurement
The paper presents results of the air permeability building measurement – a pilot project of the family house which has been built within the town of Kosice area. The house has been constructed according to the principles and requirements of passive buildings design. In the paper you will find the construction proceedings related to a proof of the building air permeability. These were used during the construction with an aim to fulfil the air permeability requirements, which were checked by the in situ measurement. A final analysis of the results gives us an idea on used materials, products, project work, designed details and construction proceedings related to preventing or eliminating the possible shortcomings which may cause the decrease of air permeability of a building.
Keywords: air permeability of building, in situ measurements, testing, defects