- Research Article
- 10.3846/est.2021.18457
- Jan 11, 2023
- Engineering Structures and Technologies
- Lukas Gritėnas + 1 more
This paper presents the assessment of masonry wall defects in residential buildings in Lithuania. The created model is based on a multi-attribute evaluation of wall defects in residential buildings in Lithuania, the determination of their optimality criterion values calculated according to Laplace’o rule. The developed defect assessment algorithm has advantages to be used by repair contractors and people or companies performing building maintenance. First, the model allows planning the course of repair works properly. When carrying out repair work in a building with recurring defects that mainly occur at the building site, proper workflow and its planning are essential. The proposed model could be applied further to a building owner to select the most damaged walls. A background and a description of the proposed model are provided, and several key findings from the data analyses are presented.
- Research Article
- 10.3846/est.2021.18402
- Jan 10, 2023
- Engineering Structures and Technologies
- Povilas Dabrila
Cable-stayed bridges are known as one of the most effective and graceful forms of bridges. The main problem in the design of cable-stayed steel bridges is their deformability, especially under asymmetrical loads. Stabilization of the initial form of cable-stayed bridges can be achieved by selecting the appropriate cross-sectional area of the cables and their pre-stressing, as well as by increasing the cross-sectional height of the stiffness beam. However, a greater effect can be achieved by applying new forms of such bridges. Solutions for such bridges with an atypical arrangement of cables and additional pylons are already applied in practice. The article discusses an innovative pre-tensioned intersecting cable steel bridge structure system. The behavior of this bridge system under permanent and temporary loads is analyzed. Based on the performed numerical experiment, the efficiency of the innovative cable-stayed steel bridge system was determined. This newly designed bridge system is more effective in terms of stress and displacement distribution than a classic cable-stayed bridge system.
- Research Article
2
- 10.3846/est.2021.18404
- Jan 10, 2023
- Engineering Structures and Technologies
- Maosheng Zheng + 2 more
In the present paper, a new concept of favorable probability is proposed first, and a simplified approach for multi-criteria decision-making is developed on basis of probability theory. It assumes that all the performance indexes of all alternatives can be divided into beneficial and unbeneficial types in the multi-criteria decision-making, and each performance index of all alternative makes its contribution to a partial favorable probability in positively or negatively correlative manners linearly upon its type of beneficial or unbeneficial; the partial favorable probability of each performance index with the same physical meaning is normalized in the alternative group; the product of all partial favorable probability of an alternative makes the total favorable probability of the alternative. As a consequence, all the alternatives can be ranked according to their total favorable probability comparatively in the multi-criteria decision-making. As application examples of the new method, the quantitative assessment of multi-criteria selection for effective dwelling house walls, project managers and contractor for construction works are given in detail, satisfied results are obtained.
- Research Article
- 10.3846/est.2022.23007
- Dec 30, 2022
- Engineering Structures and Technologies
- Maria Loebjinski + 3 more
The evaluation of the load-bearing capacity of existing structures is a central and important part in the work of structural engineers. Currently, engineers are confronted with the challenge of applying design rules developed for new structures in the evaluation of existing ones as no specific recommendations exist on a European level. As a contribution to this, a first step of this study is the evaluation of the reliability level of timber elements subjected to common limit states. Based on these analyses, modifications of the target reliability and of partial safety factors (PSF) for existing structures on the resistance side are studied. Considering a modification of the target reliability, the PSF for the material strength could be proposed with γM,opt = 1.20 for compressive and flexural strength in limit states, where variable actions are present. Additionally, options for incorporating updated material parameters from a survey on site supported by technical devices are discussed and further need for research is identified. Subsequently, this paper provides a stepwise evaluation procedure including modified PSF considering both, an update of the target reliability and update of the material parameters obtained by a survey on site and is thus adaptive for different individual cases and level of information. First published online 10 February 2025
- Research Article
1
- 10.3846/est.2022.18403
- Dec 30, 2022
- Engineering Structures and Technologies
- Edmundas Beivydas Edmundas Beivydas
The article consists of 3 parts. String analyzes with symmetrical loading, combined parametric analyzes of string structure with symmetrical loading and combined string structure analyzes with asymmetrical loading. Through various parameters, the influence of different parameters of the string on its behavior is revealed. The influence of prestressing in the combined string structure is also released. To assess the correctness of the results, an experimental study was carried out in the laboratory, after the structure was designed from steel elements.
- Research Article
5
- 10.3846/est.2021.17181
- Jul 8, 2022
- Engineering Structures and Technologies
- Gürkan S Kumbaroğlu + 2 more
A techno-economic analysis is performed for a solar farm with a 35 MWe installed capacity using bifacial solar panels and compared with standard monofacial solar panels at the same installed capacity level. The bifacial panel usage gain from total panel efficiency is identified from 4-year measurements to be within a range of 7.9–16.8% depending on monthly yield. A Monte Carlo simulation is carried out to forecast electricity prices under uncertainty. In terms of Net Present Value, it is found that the bifacial farm yields 12.6% higher values than the monofacial options under reference assumptions. An incremental internal rate of return (IRR) analysis is carried out yielding an IRR for the bifacial panels of 44% under various scenarios. The sensitivity analysis reveals that results are highly sensitive to discount rate and lifetime, and less sensitive to electricity prices. SWOT analysis performed to compare the bifacial with the monofacial panel and evaluate panels according to internal and external factors. The study was concluded with a summary of the technical specifications based on the test results. The results were used to identify that 12.2% added net present value corresponding to $186.7 – $214.5 per unit MW (under various electricity price trajectories) can be used as a reference for assessing the benefit for usage of bifacial PV for 35 MW type medium-size projects. In summary, it is suggested that bifacial solar PV with its outstanding techno-economic results can be the driving force of the growing solar PV market.
- Research Article
- 10.3846/est.2021.15036
- Jul 8, 2022
- Engineering Structures and Technologies
- Florian Sternsdorff + 2 more
The paper describes some of the experiments carried out at the Chair of Steel and Timber Construction to reinforce steel with adhesively bonded CFRP lamellas. The first topic deals with the repair of cracks in steel structures exposed to fatigue. The aim was to extend the remaining service life of these components by means of adhesively bonded CFRP lamellas and then to compare the results obtained with established methods for repairing cracks. In order to improve the informative value of the investigations, several test parameters such as adhesive candidates, temperature, creep effects, degrees of prestressing, load levels and the position of the reinforcement measures were varied. The second set of topics examined the extent to which a typical steel beam-to-column connection can be reinforced with the help of adhesively bonded CFRP lamellas.
- Research Article
- 10.3846/est.2020.15120
- Jun 16, 2021
- Engineering Structures and Technologies
- Arūnas Jaras
The stiffness analysis of the simple supported hybrid bisteel I-section beam subjected by uniformly distributed load is considered in this paper. The hybrid bisteel I-section beam presents a composition of high-strength steel inclusions for the flanges in the region of maximum stresses and of low-strength steel for remaining volume of the beam. The explicit analytical model for evaluation of stiffness of the beams mentioned is presented. The geometrical linear approach and elastic plastic material model have been assumed. The application of high-strength steel inclusion in case perfectly elastic state of the hybrid bisteel I-section beam, increase the deflection insignificantly (up to 10%). While strain hardening effect reduces the deflection by about 4 times compared to the perfect plasticity. The verification of the theoretical analysis has been performed by the FEM. After simple transformations, the proposed model can be easily applied to the evaluation of stiffness of otherwise loaded and supported hybrid bisteel I-section beams.
- Research Article
- 10.3846/est.2020.13737
- Jun 15, 2021
- Engineering Structures and Technologies
- Tatjana Grigorjeva + 1 more
Suspension bridges are characterized by exceptional architectural expressions and excellent technical and economic properties. However, despite all advantages, suspension bridges have a few negative features. Suspension bridges with flexible cables share excessive deformation caused by the displacement of kinematic origin. In order to increase the stiffness of suspension bridges, an innovative structural solution refers to rigid cables used instead of the flexible ones. The paper describes a methodology for calculating an asymmetric single-pylon suspension bridge with rigid cables considering installation features. Also, the article presents the numerical simulation of the bridge and determines the accuracy of the proposed methodology.
- Research Article
- 10.3846/est.2020.14933
- May 19, 2021
- Engineering Structures and Technologies
- Loreta Kanapeckienė + 3 more
Development of real estate has the potential to advance sustainability. This is particularly important in residential sector as it plays a crucial role in the lives of habitats and directly influences their welfare. As populations grow and cities expand, the demand for real estate increases and construction volumes rise. Assurance of sustainability in the residential projects becomes a new concern of real estate developers and construction companies. This article aims to analyse in more detail the concept of a sustainable residential construction and the evaluation criteria. In the first part the concept of sustainable development and its dimensions in residential construction are analysed. The second part describes the research methodology. In the third part, the research methodology is applied to the evaluation of five residential construction projects in Vilnius, Lithuania. The fourth part describes the possibilities of using wooden construction to improve the sustainability of residential construction projects.