Banca de DEFESA: LEONARDO MEDEIROS DA COSTA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LEONARDO MEDEIROS DA COSTA
DATE: 09/11/2022
TIME: 09:00
LOCAL: Pos Graduação Engenharia Civil
TITLE:

Rehabilitation of Fire-Damaged Reinforced Concrete Beams: Shear Strengthening with NSM CFRP

KEY WORDS:

residual strength; post-fire shear capacity; analytical models

PAGES: 162
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

It is essential to know the residual strength of structures after fire, and to define a diagnosis: release, demolition, repair and/or structural strengthening. After fire, reinforced concrete (RC) beams usually lose their strength, requiring strengthening. One solution is the use of the NSM (near-surface mounted) technique in strengthening with CFRP (carbon fiber reinforced polymer) laminates. Despite the proven efficiency of the beams shear strengthening system, the analytical models present great dispersion compared to the few experimental results available. As for the strengthening of the beams after fire, the scenario is even more scarce and without a proposal for an analytical formulation. Therefore, the present work developed an experimental series with 16 RC beams, analyzed at room temperature and after fire, with and without shear strengthening. A group of beams was heated at times of 60, 90 and 120 min, according to ISO 834 (2014) fire curve, slowly cooled, and strengthened with CFRP laminates and the NSM technique. The laminates were applied at 45º and spaced at 75, 150 and 200 mm. The beams were tested to failure in the 3-point bending test, evaluating the load capacity, ductility, and stiffness. The NSM CFRP system was efficient, recovering the beams' initial shear capacity, and even increasing it considerably. The smaller spacings between the laminates resulted in greater load capacities, deformability and rigidity. An analytical study was carried out, and three procedures were presented: (1) it estimated the residual capacity of the beams. Validation was performed with experimental results from 62 beams available in the literature. The proposal presented for the bending moment an average ratio (analytical/experimental) of 1.04, and for the shear capacity an average ratio (analytical/experimental) of 0.83. In (2) a design proposal the shear strengthening at room temperature. A total of 70 experimental results from seven authors were used to evaluate the performance of the procedure and compare it to four analytical models. The proposed procedure presented an average ratio (analytical/experimental) of 0.94, and a lower coefficient of variation (CV). In (3) a design proposal after fire of the shear strengthening was based on the contributions (1) and (2) above, and validated based on the experimental results of eight beams developed in this research. The shear capacity (analytical/experimental) presented an average ratio of 0.82 and CV of 12.2%, showing to be a promising simplified procedure, and pioneer, in the design of the shear strengthening of RC beams after fire.

COMMITTEE MEMBERS:
Externo à Instituição - JOSÉ ALEXANDRE GOUVEIA HENRIQUES
Externo à Instituição - CRISTIANO CORREA
Presidente - 2250444 - RENATO DE SIQUEIRA MOTTA
Interna - 1128124 - ROMILDE ALMEIDA DE OLIVEIRA
Externo à Instituição - SEVERINO PEREIRA CAVALCANTI MARQUES - UFAL