The effectiveness of anovel Post-Tensioned Metal Strapping(PTMS)techniqueat enhancingthe seismic behaviourof asubstandard RC buildingwas investigated through full-scale shake-tabletests duringthe EU-fundedproject BANDIT.The building had inadequate reinforcement detailing in columns and joints toreplicateold construction practices.After thebarebuildingwas initially damagedsignificantly,itwas repairedand strengthened with PTMS to perform additionalseismic tests.The PTMS technique improvedconsiderablythe seismic performance of the tested building.Whilst the bare building experienced critical damageatan earthquake of PGA=0.15g, thePTMSstrengthened building sustained a PGA=0.35gearthquake without compromising stability.
Construction has always been considered a major producer of serious environmental problems due to large consumption of resources in terms of materials and energy accompanied by environmental pollution; therefore, the projects aiming to reduce these damaging effects are more than welcome. The objective of sustainable development is difficult to be performed by civil and structural engineers at a global scale. However, some solutions and systems for load bearing and cladding elements that make the buildings or other types of civil engineering applications may contribute, at least partially, to attaining some goals of sustainability. Fiber reinforced polymeric (FRP) composite structures and hybrid systems may become sustainable when they utilise minimum material resources, increase the life span of buildings, have a very low environmental impact and ensure the high quality of civil infrastructures. The main objectives of the paper are related to the use of FRP composites in new construction components as well as rehabilitation of deteriorated civil engineering structures aiming to achieve sustainable solutions in civil and structural engineering. Starting from the concept of FRP composites and hybrid systems the authors describe a number of research and development projects carried out by the Composite in Construction Research Group (CCRG) at the Faculty of Civil Engineering, "Gheorghe Asachi" Technical University of Iasi. After a critical evaluation of FRP composite materials applied in construction, the authors describe and analyse their results which addressed a long term program including: all composite structures, multilayered sandwich construction, concrete elements reinforced with FRP composite bars, and modern solutions for structural rehabilitation of load carrying elements made of traditional building materials aiming to improve the building components performance.
This paper presents the results of laboratory studies, undertaken by the authors, in the frame of 4D-POSTDOC research program :"Innovative technologies and logistical solutions for the reuse of demolition and construction waste in the construction of cement concrete and fiber reinforced cement concrete pavements". After the presentation of the main objectives of this research program, and of the specific characteristics of the demolition wastes investigated in parallel with those of conventional construction materials, the possibility of using these materials for the preparation of the roller compacted concrete (RCC) is investigated. Finally, conclusions on the influence of recycled aggregates and recycled steel fibers on the mechanical performances of RCC and technical recommendations for the use of this more efficient material and of the involved technology for the construction of sustainable road infrastructures are formulated.
Design and verification of engineering structures require knowing the numerical values of sectional internal forces as close to reality, considering that the intervention construction works are correlated with these values.Most of the computer programs are working with finite element method, which was designed by engineers and founded by mathematicians. After running the computer program, stresses and deformations maps are generated as results.Considering these results, using artificial neural networks, a computer program has been designed, which is able to determine internal forces of a section, namely axial force, shear force and bending moment.Neural network input parameters consist of color maps resulted from numerical modeling, numerical values of the normal and tangential tensions and dimensions of the structural element.This procedure is particularly useful when using finite element programs that do not have the ability to determine sectional internal forces.
The paper presents experimental and numerical investigations on the behaviour of rubberized concrete short columns confined with aramid fibre reinforced polymer (AFRP) subjected to compression. Additionally, the possibilities to substitute fine aggregate with crumb rubber granules, obtained from discarded worn tires, in structural concrete is also assessed. Because replacing traditional concrete aggregates by rubber particles leads to a significant loss in compressive strength, the authors highlight the use of AFRP confinement to partially or fully restore the compressive strength by applying a number of 1, 2, and 3 layers. Analytical models available for confined regular concrete are used to predict the peak stresses and the corresponding peak strains. Some analytical models give accurate results in terms of peak stress while others better approximate the ultimate strain. The full stress-strain curve of rubberized concrete and the experimentally obtained values for the material properties of AFRP are used as input data for the numerical modelling. A good agreement is found between the results obtained for the peak stress and corresponding axial strain from both the numerical simulations and the experimental investigations.
Capacity design concept for reinforced concrete frame systems is based on a hierarchy of the strength and stiffness properties of the structural elements so that the seismic energy dissipation mechanism occurs in a certain way. This theoretical concept of seismic energy dissipation by allowing the occurrence of plastic hinges at the end of the beams and the columns located at the ground floor was not observed / identified in post-earthquake inspection of damaged RC frame structures. On the other hand, various failure mechanisms were observed that are not compliant with theoretical considerations specified in the seismic design codes. The damages produced during the latest seismic events, (2020 Zagreb earthquake, 2020 Aegean Sea earthquake, 2020 Caribbean earthquake, 2020 Puerto Rico earthquake, 2020 Mexico earthquake, etc.) raised some concerns related to the theoretical ductile failure mechanism (Strong Column -Weak Beams, SCWB) versus the practical approach. Consequently, a possible improvement of the capacity design concept through the consideration of different values for the behaviour factor "q" applied to structural elements (beams and columns) was investigated and presented in this paper. The goal was to reach the expected theoretical structural degradation mechanism. Thus, by considering different values for the behaviour factor "q", at the design stage, for beams and columns, it was possible to reach a favourable value for the ratio Kc/Kb between the bending stiffness of columns (Kc) and beams (Kb). Consequently, a good correlation between the real seismic response and the theoretical mechanism of structural deformation was obtained.
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