Arnoldas Šneideris

Flexural capacity and stiffness of monolithic biaxial hollow slabs

The article presents a research on flexural behaviour of hollow monolithic reinforced concrete slabs. It focuses on the results of experimental investigation into full-size hollow reinforced concrete slabs and analyses their flexural capacity and stiffness. The self-weight of the slabs directly depends on the shape and number of hollows. An increase in the hollowness of a slab significantly reduces the load caused by self-weight. This allows increasing the estimated length of the slab under the same payload. An increase in the amount of hollows of the slab changes the stiffness of the slab cross-section that has a direct impact on slab deflection. Considering the shape of the slab cross-section, theoretical calculations of the flexural capacity and deflection of experimental slabs were made. The design of a new type of slabs and variations in different parameters of the slab experience difficulties in conducting a large amount of experimental tests. Therefore, the initial analysis may apply to numerical simulation. The paper describes the principles of designing a numerical model. The calculations were made using DIANA software. The stiffness and flexural capacity of the hollow slabs were established employing numerical simulation compared to the results of experimental investigations. The findings indicate that numerical simulation can be applied for analysing the stress state of the examined structures.

Flexural reinforced concrete elements normal section bearing capacity evaluation in fracture stage

AbstractThis article examines flexural reinforced concrete structures condition assessment process in existing buildings on the stage where the reinforcement stress is between the yield and the tensile strength. The research is made on V. Jokūbaitis proposed methodology directly measuring the compression zone height, allowing us to evaluate the behavior of reinforced concrete beam fracture sufficiently precisely. This paper confirms the hypothesis that, when reinforcement reaches yielding stress, elastic strain dominates in concrete’s compression zone and it is reasonable to use triangular concrete compression zone diagram, without tensile concrete above crack evaluation. The methodology of reinforced concrete structures bearing capacity assessment according to limit normal section crack depth is proposed. There is established connection between bending moments, when reinforcement achieve yielding stress and tensile strength, which allows us to decide about structures bearing capacity reserve. The results...

Aukštos temperatūros įtakos betono ir armatūros savybėms bei jų bendrai elgsenai analizė

Santrauka Nagrinėjama gelžbetonio ir jo komponentų (betono ir armatūros) elgsena aukstoje temperatūroje, tiriamos betono stiprumo ir deformatyvumo savybės kintant temperatūrai. Atliekama teorinių ir eksperimento būdu gautų rezultatų lyginamoji analizė. Aptariami pagrindiniai atsparumo ugniai skaiciavimo principai. Pasinaudojus baigtinių elementų metodo programa COSMOS/M, suskaiciuoti gelžbetoninio elemento skerspjūvio temperatūros pasiskirstymo laukai pagal standartinio gaisro kreive. Pagal gautus temperatūrinius laukus zonų metodu nustatyta teorinių ir eksperimento rezultatų skirtumo įtaka elemento laikomajai galiai.

STRAIN-STRESS ANALYSIS OF REINFORCED CONCRETE BEAMS STRENGTHENED WITHOUT UNLOADING BY EXTERIOR REINFORCEMENT

Summary The mostly used method for strengthening flexural concrete members is mounting exterior reinforcing bars. When applying the strengthening by exterior reinforcing, the problem of assessing the remaining carrying capacity of the member being strengthened and estimating the actual stress in the reinforcement placed in the tensile zone of the member is to be solved. In the paper a method for the analysis of the flexural concrete members strengthened by exterior reinforcing bars is proposed. The method allows to design the exterior reinforcement by taking account of the remaining carrying capacity of the member being strengthened. Moreover, the method proposed enables one to assess a redistribution of stress between the originally placed reinforcement and the exterior reinforcement used to strengthen the member. The redistribution of stress has a considerable influence on the carrying capacity of the member as well as on its bending stiffness. The stress-strain relationships of the both reinforcements ...