STRENGTHENING OF HYDROSTATICALLY LOADED CYLINDRICAL STEEL TANKS USING GFRP
MOHAMED HAMDY ALY ESMAIL;
Abstract
This study investigates a new method of strengthening cylindrical tanks subjected to hydrostatic load. Small amount of glass fibre-reinforced polymer (GFRP) composite, used at a critical location, can effectively increase their buckling strength. A 3-D finite element model was developed to study the behaviour of cylindrical tanks with and without GFRP subjected to hydrostatic load. The finite element model was developed using ANSYS program. The state of instability under the influence of geometric and material nonlinearity is studied. The developed 3-D finite element model was compared and verified to previously published data.
12 tanks with variable dimensions and thicknesses were studied. The radiuses (R) of tanks selected are 5m, 7.5m, and 10m. The H/R values selected are 1.00, 1.50, 2.00, and 2.50, where H is the total tank height. The results obtained from the finite element analysis for steel tanks without and with strengthening of GFRP height equal to 0.3H and different thicknesses are presented.
Comparison between the buckling strength of perfect cylindrical steel tanks with and without GFRP was presented. The results show the benefit of using GFRP as a strengthening method for such structure. The strengthening effect is shown to be sensitive to the thickness, location of the GFRP sheets.
Although perfect tanks are considered in this investigation, which is not the real case as the buckling strength decrease by including the imperfection but this, is a comparative study to show the effect of the strengthening cylindrical tanks with GFRP.
6.2 Conclusion
According to the results and observations of the present study as related to the tank response under hydrostatic loading condition, the following conclusions can be drawn:
- The buckling wave occurs at the base of tank which called elephant foot buckling at a height ranging from (0.25H to 0.35H) measured from base.
- The GFRP is applied over the lower part with a height 0.25H from the tank base where the buckling occur.
- GFRP layer carries part of the hoop stress thus helps in delay of steel yielding as well as supporting the tank after the stress reaches its yield point.
- Strengthening with GFRP layer with thickness = 1mm give tank capacity increment ranging from 7% to 58%.
- Strengthening with GFRP thickness of 2mm the tank capacity increment ranging from 12% to 64%.
- Strengthening with GFRP thickness of 3mm the tank capacity increment ranging from 17% to 76%.
- Strengthening with GFRP thickness of 4mm the tank capacity increment ranging from 22% to 85%.
6.3 Recommendations for Future Work
Future research could be directed to:
- Study the effect of Imperfection of tank wall plates on the buckling strength.
- Study the effect of changing the thickness of tank wall along the tank height.
- Study the effect of hydrodynamic loading results from earthquake loads and wind loads on the tank response.
- Study a new strengthening teqniques.
12 tanks with variable dimensions and thicknesses were studied. The radiuses (R) of tanks selected are 5m, 7.5m, and 10m. The H/R values selected are 1.00, 1.50, 2.00, and 2.50, where H is the total tank height. The results obtained from the finite element analysis for steel tanks without and with strengthening of GFRP height equal to 0.3H and different thicknesses are presented.
Comparison between the buckling strength of perfect cylindrical steel tanks with and without GFRP was presented. The results show the benefit of using GFRP as a strengthening method for such structure. The strengthening effect is shown to be sensitive to the thickness, location of the GFRP sheets.
Although perfect tanks are considered in this investigation, which is not the real case as the buckling strength decrease by including the imperfection but this, is a comparative study to show the effect of the strengthening cylindrical tanks with GFRP.
6.2 Conclusion
According to the results and observations of the present study as related to the tank response under hydrostatic loading condition, the following conclusions can be drawn:
- The buckling wave occurs at the base of tank which called elephant foot buckling at a height ranging from (0.25H to 0.35H) measured from base.
- The GFRP is applied over the lower part with a height 0.25H from the tank base where the buckling occur.
- GFRP layer carries part of the hoop stress thus helps in delay of steel yielding as well as supporting the tank after the stress reaches its yield point.
- Strengthening with GFRP layer with thickness = 1mm give tank capacity increment ranging from 7% to 58%.
- Strengthening with GFRP thickness of 2mm the tank capacity increment ranging from 12% to 64%.
- Strengthening with GFRP thickness of 3mm the tank capacity increment ranging from 17% to 76%.
- Strengthening with GFRP thickness of 4mm the tank capacity increment ranging from 22% to 85%.
6.3 Recommendations for Future Work
Future research could be directed to:
- Study the effect of Imperfection of tank wall plates on the buckling strength.
- Study the effect of changing the thickness of tank wall along the tank height.
- Study the effect of hydrodynamic loading results from earthquake loads and wind loads on the tank response.
- Study a new strengthening teqniques.
Other data
| Title | STRENGTHENING OF HYDROSTATICALLY LOADED CYLINDRICAL STEEL TANKS USING GFRP | Other Titles | " تدعيم الخزانات الاسطوانية المعدنية باستخدام الالياف الزجاجية البوليمرية المقواة." | Authors | MOHAMED HAMDY ALY ESMAIL | Issue Date | 2015 |
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