Static Analysis And Design Of Laterized Concrete Cylindrical Shells For Farm Storages

ABSTRACT

As the prices of building materials in the country continue to increase

sharply, there is growing need to source local materials as alternative for

farm building constructions. This project investigates the performance of a

cylindrical shell built of laterized concrete for storage of foodgrains or water.

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In order to optimize the mix ratio of the constituent materials that will

produce maximum strength, a mathematical model which relates the strength

of laterized concrete and its component ratios was developed using Scheffe's

simplex lattice approach. The optimum mix proportion obtained was used to

determine the structural characteristics of laterized concrete in the laboratory.

The values obtained for the material properties were applied in performing

the static analysis of the cylindrical shell structure under the action of

hydrostatic and foodgrain pressures using Pasternack's equations formulated

on the basis of theory of shell of revolution. The reduced equation of static

equilibrium was solved by the Initial-value method. A generalized solution of

the cylindrical shell made of laterized concrete was obtained and used to

evaluate the performance of the structure through the determination of

deflection and stresses. Adequate cross-section of the cylindrical shell was

determined.

The experimental data are very well fitted to the regression model,

which satisfies the student-t and chi-square tests. The optimum strength value

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of 2 7 N l d corresponding to an optimum mix proportion of 1 : 1 :2:0.650 of

cement, laterite, gravel and water-cement ratio respectively was predicted by

the model. For the structural characteristics, the values obtained for the

optimum mix ratio were higher than that obtained for the mix ratio of

1 :2:4:0.791. The results of the analysis indicate that the maximum stresses

developed due to hydrostatic loading is greater than the strength of the

laterized concrete in reservoir thickness of 5Omm, 1 Om in diameter and 5m in

height. The wall thickness of 100- was found adequate. The maximum

stress developed due to soybean grain loading is greater than the material

strength in silo thickness of 100mrn, 20m in diameter and 8m in height. The

wall thickness of 150mm was found adequate. Thus, the possibilities of using

laterized concrete in constructing cylindrical storage structures were successfully demonstrated.