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  Numar curent

Volumul 13 (2022), Nr. 3

Modelare numerica pentru analiza inginereasca, proiectarea si monitorizarea sistemelor de suport pentru tunelul cu doua tuburi
Numerical Modeling for Engineering Analysis, Designing and Monitoring of Support Systems for Twin-Tube Tunnel

In this research work, Rock Mass Rating (RMR) was used for the characterisation of rock mass along the tunnel alignment based on physical, geological and geotechnical data of the project area. The support systems were recommended for all geotechnical units using RMR and tunneling quality index (Q-system) support chart. Furthermore, Various design input parameters such as physical and geotechnical properties, in situ stresses, modulus of deformation of rock mass, support systems recommended by RMR were used as input parameters in Phase2 2D 8.0 software, in order to compare the calculation results with in-situ monitoring using Amberg Tunnel 2.0 software, to validate the numerical models and to check the deformations of the tunnel in the temporary support stage

Keywords: Tunnel, Rock Mass Ckassification, Provisional Support, Deformations, Numerical Modelling.

Investigatie experimentala si numerica asupra efectului benzilor CFRP cu unghiuri de orientare diferite asupra rezistentei fasciculului
Experimental and Numerical investigation on the effect of CFRP straps with different orientation angles on the strength of the beam
Gandla Nanabala Sreekanth, S.Balamurugan

Now a days all the civil engineering structures are designed earthquake resistant to withstand the high intensity earthquakes that are occurring more frequently. But there is a need to strengthen the already existing structures to withstand for earthquakes. Usage of CFRP sheets is a technique to strengthen a structural member of a structure to withstand for natural occurring calamities. This study presents the experimental and numerical investigation on the effect of CFRP sheets with varying angles of straps on the strength of the beam. The objective of this work is to explore the behaviour of RC beam strengthened with CFRP sheet and straps. Numerical analysis was carried out using software to represent the ultimate load vs deflection and ultimate load carrying capacity of the beam. Comparison of experimental with numerical results exhibited, that beam strengthened with angled straps showed more effective in enhancing the deflections, failure modes and ultimate strength of the RC beam. The strength of CFRP straps with different orientations were analyzed and compared.

Keywords: Unidirectional carbon fiber, epoxy, load versus, deflection graph, ultimate load carrying capacity

Material de constructie poros termoizolant fabricat din deseu de sticla reciclata prin incalzire cu microunde
Porous thermal insulation building material made of recycled glass waste by microwave heating
Lucian Paunescu, Sorin Mircea Axinte, Bogdan Valentin Paunescu, Felicia Cosmulescu

Lucrarea prezinta rezultate experimentale obtinute in procesul fabricarii sticlei celulare utilizand incalzirea indirecta cu microunde. Intensificarea absorbtiei microundelor a fost realizata utilizand un creuzet din carbura de siliciu avand peretele acoperit cu un film din oxid de ytriu. Incălzirea cu microunde si folosirea oxidului de ytriu reprezinta originalitatea lucrarii. Reteta continand deseu de sticla, cenușa si carbura de siliciu a permis producerea sticlei celulare la 960-970 ºC cu consumuri economice de energie (sub 0,86 kWh/kg). Produsele au caracteristicile specifice sticlei celulare cu densitatea intre 0,27-0,33 g/cm3, conductivitatea termica intre 0,064-0,073 W/m·K si rezistența la compresiune intre 1,35-1,45 MPa.

Cuvinte Cheie: sticla celulara, incalzire cu microunde, deseu de sticla, cenusa de carbune, carbura de siliciu, oxid de ytriu.

The paper presents experimental results obtained in manufacturing process of cellular glass using the indirect microwave heating. The microwave absorption intensification was achieved using a silicon carbide crucible having the wall coated with a yttrium oxide film. The microwave heating and the use of yttrium oxide are the paper originality. The recipe containing glass waste, ash and silicon carbide allowed cellular glass production at 960-970 ºC with economical energy consumption (below 0.86 kWh/kg). The products have specific characteristics of cellular glass with density between 0.27-0.33 g/cm3, thermal conductivity between 0.064-0.073 W/m·K, and compressive strength between 1.35-1.45 MPa

Keywords: cellular glass, microwave heating, glass waste, coal ash, silicon carbide, yttrium oxide.

Aspecte privind calculul peretilor structurali din zidarie
Aspects on the masonry structural walls computation
Robert Draghici, Ana Maria Parvanus, Daniel Stoica

Codul romanesc CR6-2013, pornind de la EC6, propune 3 tipuri de pereti structurali din zidarie, care pot sa fie utilizați la cladirile cu structura de rezistenta din zidarie. Prezentul articol, isi propune identificarea raspunsurilor acestor tipuri de pereti, pentru diferite niveluri de forte axiale NEd si dimensiuni ale pereților structurali.

Cuvinte Cheie: structuri, zidarie, pereti, momente incovoietoare

The Romanian code CR6-2013, starting from EC6, proposes 3 types of structural masonry walls, which can be used for buildings with masonry resistance structure. This article aims to identify the answers of these types of walls, for different levels of axial forces NEd and dimensions of structural walls.

Keywords: structures, masonry, walls, bending moment

Studiu numeric neliniar al raspunsului dinamic al rezervorului conic de otel ridicat sub excitatie seismica
Non-linear numerical study of the dynamic response of elevated steel conical tank under seismic excitation
Nasser Dine Hadj Djelloul, Mohamed Djermane, Noor Sharari

Elevated cylindrical and conical steel tanks are widely used to conserve water or chemical liquids. These important structures are required to stay protected and operative at any time. The wall angle inclination of conical tank part,as well as the presence of the vertical earthquake component, can cause damage to this structure and even lead to its failure. The purpose of this study is to examine the effect of the wall angle inclination of the tank and the vertical earthquake acceleration component on the nonlinear dynamic stability of the elevated steel conical tanks under seismic excitation. The elevated steel conical tank is simulated utilizing the finite element analysis method using ANSYS software. The fluid-structure interaction is considered using a suitable interface that allows the fluid to apply hydrodynamic pressures on the structure. Three different models, namely Model –A-30°, Model –B-45°and Model –C-60°were investigated; it has been concluded that the impact of inclination of the tank wall significantly affects the nonlinear stability of the elevated steel conical tank. While considering the vertical ground acceleration, inclination plays a significant role in the design of this type of structures. Therefore, it should be appropriately included in the seismic analysis of elevated steel conical tanks to satisfy the safety of the elevated steel conical tank response under seismic loading.

Keywords: Non-linear dynamic analysis, Fluid–structure interaction, Steel conical tanks, Stability,Vertical acceleration

Considerarea riglele de cuplare la peretii din zidarie
Regarding the coupling beams in the calculation of the masonry walls
Robert Draghici, Ana Maria Parvanua, Daniel Stoica

Pereții de zidarie functioneaza in mod normal legați fie prin placi, prin grinzi de cuplare din zidarie, beton armat sau prin sectiuni compozite (zidarie si beton armat etc.). Comportamentul grinzilor de cuplare, inclusiv in codurile de proiectare actuale, este insuficient abordat, cunoscut si tratat. Din acest motiv, efectul indirect al pereților adus de grinzile de cuplare este insuficient cunoscut - majoritatea proiectanților (din lipsa de informații) preferă sa nu-i ia in considerare in calculul general. Dupa testele efectuate pe mese seismice pe modele 3D, dar si dupa cutremurele majore, reale, se poate observa cu usurinta influenta deosebita a grinzilor de cuplare asupra comportarii de ansamblu a peretilor structurali de zidarie (de tip montanți sau spalete). Toate acestea atat pentru pereți structurali sau despartitori, cat si pentru pereți normali sau de calcan. Deoarece aceste date nu sunt suficient de bine cunoscute in practica de proiectare, acest studiu incearcă sa arate cum prin utilizarea programului ETABS, fie pentru energia disipata, fie pentru energia de distorsiune, putem obtine indicații suficient de sugestive despre comportarea riglelor de cuplare, precum si a pereților de zidarie.

Cuvinte Cheie: structures, masonry, coupling beam, dissipated energy

Masonry walls normally work connected either by floor slabs, by coupling beams made from masonry, reinforced concrete or by composite sections (masonry and reinforced concrete, etc.). The behavior of the coupling beams, including in the current design codes, is insufficiently approached, known and treated. For this reason, the indirect effect of the walls from the coupling beams is insufficiently known - most designers (due to lack of information) prefer not to consider them in the overall calculation. After the tests performed on seismic masses on 3D models, but also after the major, real earthquakes, one can easily see the special influence of the coupling beams on the overall behavior of the structural masonry walls (cantilevers or piers type). All bout these both for structural or partition or for normal and blind walls. Because these data are insufficiently well known in design practice, this study attempts to show how by using the ETABS program, for either dissipated energy or distortion energy, we can get sufficiently suggestive indications about the behavior of coupling beams as well as masonry walls.

Keywords: structuri, zidarie, rigla de cuplare, energie disipata

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