A simple solution for a crack reinforced by bands

The paper represents a simple approximate solution for a crack reinforced by elastic bands (springs). The obtained results for the stress intensity factor are compared with the exact solutions for the case of infinitely rigid bands. The agreement is quite good and in view of its simplicity the proposed approach has some advantages when compared with the existing solutions. Finally, a modest experimental effort was undertaken to demonstrate qualitatively the validity of the numerical approach

Fracture of reinforced concrete beams subjected to three point bending

The present paper investigates deformation of three point bent reinforced concrete (RC) beams analytically (using fracture mechanics), computationally (using finite element method) and experimentally. As the applied force increases the crack is initially trapped by the reinforcement. The debonding of the reinforcement is attributed to the horizontal crack. Simultaneously, the vertical crack propagates driven by the externally applied force. The reinforcement behaves as clasto-plastic spring that decreases the stress intensity factor. The developed analytic model provides estimates of the collapse load, crack length and crack opening displacement. The ultimate loading is estimated by the numerical smeared crack model, incorporated in nonlinear finite element code DIANA. Experimental measurements are used to verify theoretically and numerically obtained results. Special attention is focused on the determination of vertical crack size using graphite and optical fibers

Otkrivanje oštećenja određivanjem dinamičkih karakteristika

The change of dynamic parameters (stiffness, damping), as a consequence of structural history (erosion, friction, fatigue, internal damages and cracks), has an impact on decrease of reliability and serviceability of a structure or, drastically, causes its collapse. Having in mind that structural damage is small or embedded in the system, hence the detection cannot be done visually, one useful non-destructive procedure for damage determination by dynamic parameters evaluation - vibration monitoring of the structure.Promene dinamičkih karakteristika (krutosti, prigušenja) kao posledice istorije konstrukcije (erozija, trenje, zamor, unutrašnja oštećenja i prsline) utiču na smanjenje pouzdanosti konstrukcije kao i na njenu upotrebljivost ili, u najgorem slučaju, mogu dovesti do njenog kolapsa. Imajući u vidu da je oštećenje konstrukcije malo ili unutar sistema, stoga ne može biti detektovano vizualno, u radu je predložen koristan ne-destruktivan postupak za određivanje oštećenja preko dinamičkih parametara - monitoring vibracija konstrukcije

Otkrivanje oštećenja određivanjem dinamičkih karakteristika

The change of dynamic parameters (stiffness, damping), as a consequence of structural history (erosion, friction, fatigue, internal damages and cracks), has an impact on decrease of reliability and serviceability of a structure or, drastically, causes its collapse. Having in mind that structural damage is small or embedded in the system, hence the detection cannot be done visually, one useful non-destructive procedure for damage determination by dynamic parameters evaluation - vibration monitoring of the structure.Promene dinamičkih karakteristika (krutosti, prigušenja) kao posledice istorije konstrukcije (erozija, trenje, zamor, unutrašnja oštećenja i prsline) utiču na smanjenje pouzdanosti konstrukcije kao i na njenu upotrebljivost ili, u najgorem slučaju, mogu dovesti do njenog kolapsa. Imajući u vidu da je oštećenje konstrukcije malo ili unutar sistema, stoga ne može biti detektovano vizualno, u radu je predložen koristan ne-destruktivan postupak za određivanje oštećenja preko dinamičkih parametara - monitoring vibracija konstrukcije