Structural Efficiency and Economy of Shells Foundations

This thesis introduces shell foundation as the economic alternative to traditional foundations. Through study a type of traditional foundation and two types of shell foundations. So that the foundations are based on weak soil possessing the same properties, and is subject to a high structural load. In this paper, hyperbolic and conical shell footings were designed and compared with sloped square footing. The result were found that , the shell footing more economical than sloped footing , in terms of the size of the concrete mass and the amount of reinforcing steel area. As follows, hyperbolic 48.1%, conical 41%.


Jaipur
This thesis introduces shell foundation as the economic alternative to traditional foundations. Through study a type of traditional foundation and two types of shell foundations. So that the foundations il possessing the same properties, and is subject to a high structural load. In this paper, hyperbolic and conical shell footings were designed and compared with sloped square footing. The result were found that , the shell footing more ped footing , in terms of the size of the concrete mass and the amount of reinforcing , hyperbolic 48.1%, conical , hyperbolic, conical An economic alternative to traditionally plain shallow super structural loads are to be transmitted to weaker soil is opportune hells are thin-slab ce capabilities as a supporting element rely heavily upon their form and of construction materials used. shell foundations are composed of one or more curved slabs or folded plates whose relative thickness is inferior to its overall planar dimensions. To obtain maximum structural performance, shell foundations have been prevalently designed in arched, circular, triangular, conical, cylindrical, spherical, pyramidal, The historical success of shells performance as a has motivated further research in its application and performance with the objective of exploiting cost savings benefit applied in a geotechnical engineering context. The ingenuity of shell footings as foundations has all the ingredients any design engineer should look to satisfy; that of optimum strength at minimal cost that is both safe and elegant, yet endures. This combination of economy and efficiency coupled with long the epitome of a sustainable structure Structural efficiency and economy of shells. The basic difference between a plain structural element like a slab and a non-planar structural element like a shell is that, while the former resists vertical loads, including self weight, in flexure, the same loads induce primarily a direct, in-plane or membrane state of stress in a shell, which may be tension, compression or shear, but all lying in the plane of the shell. Concrete as a material of construction is most efficient in direct compression, least efficient in tension, with the efficiency in bending lying between the two. Thus if a plain roof slab is substituted by a shell, and if the geometry and boundary conditions of the shell are such that the same applied load induces a state of membrane compression, and that too of a lo magnitude, better material utilisation results, which in terms of design means a substantial reduction in thickness.
This reduction in thickness, however, has been achieved at the cost of extra surface area needed on account of the curvature of the shel that there is a net saving in material provided the saving realised due to reduction in thickness more than offsets the extra due to curvature. Shobhanagar, Jaipur, Rajasthan, India exploiting cost savings benefit applied in a geotechnical engineering context. The ingenuity of shell footings as foundations has all the ingredients er should look to satisfy; that of optimum strength at minimal cost that is both safe and elegant, yet endures. This combination of economy and efficiency coupled with long-term durability is the epitome of a sustainable structure d economy of shells. The basic difference between a plain structural element like a planar structural element like a shell is that, while the former resists vertical loads, including self weight, in flexure, the same loads induce plane or membrane state of stress in a shell, which may be tension, compression or shear, but all lying in the plane of the shell. Concrete as a material of construction is most efficient in direct compression, least efficient in the efficiency in bending lying between the two. Thus if a plain roof slab is substituted by a shell, and if the geometry and boundary conditions of the shell are such that the same applied load induces a state of membrane compression, and that too of a low magnitude, better material utilisation results, which in terms of design means a substantial reduction in This reduction in thickness, however, has been achieved at the cost of extra surface area needed on account of the curvature of the shell, which means that there is a net saving in material provided the saving realised due to reduction in thickness more than offsets the extra due to curvature. Experimental examination of shell foundations on dry sand ˮ. the subsequent bearing limits and settlements will be contrasted and traditional strip, round, and square level foundations. The present paper exhibits a trial examine on nine establishment models tried on free, medium, and thick sand states. The impact of shell setup and insertion profundity on a definitive bearing limit and settlement will be exhibited. Three diverse stature/thickness proportion offlat and shell establishment made out of various materials.

Problem Description
Diminishing accessibility of good construction destinations and expanding construction exercises for infrastructural developments all through the world has constrained the structural specialists to use inadmissible locales or weak soil.
Turn out to be extremely important And with the requirement for multi-story undertaking, which produces colossal burdens, interestingly weak soil.
The scope of this study can be explained by explaining the requirements of code IS 9456-1980 and design requirements, comparing design results between shallow foundations and shell foundations.
The objectives of the present study are:  Study of shell foundations as an alternative to shallow foundation.  Studying the size of the underlying stress in the soil after applying the load in the case of the shell foundation and shallow foundation.  Analysis of the data obtained through this study with the data of previous studies to illustrate the economic and engineering efficiency of the shell foundation.

Proposed Methodology
Structural loads are applied to weak soil, and the foundations of shell foundations and shallow foundations of structural load applied to weak soil The design data is then compared The size is footing in both cases.
To known out the:-1. Amount of savings in building materials.
2. The amount of steel used. 3. Effective soil stress.
And we can comparing design results between shallow foundations and shell foundations. 2-Calculate membrane shear on factored load.
3-Design the steel in shell (find area of steel for tension due to shear).
(Some recommend 0.5 % as minimum steel to reduce crack width in the slab). This steel is more than, the minimum is 0.12 % for shrinkage.
4-Check compression in concrete in the shell.

5-Find tension in edge beam and area of steel as in beam.
-Max tension (each shell).

5-Design for compression
With minimum thickness for cover </ 50 mm for steel… etc Last thickness = 120 mm 6-Check where no compression steel is required (let is be S from both apex).
Compression token per mm = * ( ) 7-Check percentage of steel at bottom (where compressions least).
Assuming constant thickness of shell.
We must provide minimum steel P = * * 8-Design for maximum hoop tension @ S 2 : N t = q v * S 2 * tanӨ .
9-Design for hoop tension N t at place where column and steel meet.

DESIGNE OF SQUARE FOOTING
1-Find size of footing or dimensions. 7-Check development length, (Length from the of the column).

RESULT
Comparison between shell foundations (hyperbolic and conical footing) and sloped footing Through the comparison we came to the following results Table 1. Comparison Table   Conclusion The Hyperbolic and conical shell footing were designed and compared with sloped footing. The following conclusion can be drawn: 1) The hyperbolic shell footing were found economical than that of conventional footing, and its saves the concrete and steel up to 48.10%. 2) The conical shell footing were found economical than that of conventional footing, and its saves the concrete and steel up to 41%. 3) It gives minimum materials consumption over the conventional footing. 4) It gives the greater load capacity and stability over the conventional footing. 5) On the other hand, they need trained labor, so they are common use in East Asia due to low wages and high building materials.