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Vol 66, No.12;Dec 2016

Jokull Journal83

COMPARISON BETWEEN FLAT SLAB AND SOLID SLAB SYSTEMS

IN STRESSES DISTRIBUTION UNDER THE FOUNDATION USING

FINITE ELEMENT ANALYSIS

M. E. EL KILANY1, T. A. EL-SAYED2*, N. R. EL-SAKHAWY3, A. I. EL-DOSOKY4

1Associate Professor, Civil Str. Eng. Dep., Faculty of Eng., Zagazig University, Egypt 2Assistant Professor, Civil Str.Eng. Dep., Shoubra Faculty of Eng., Benha University, Egypt

3Professor, Civil Str. Eng. Dep., Faculty of Eng., Zagazig University, Egypt 4M.Sc Degree, Civil Str. Eng. Dep., Faculty of Eng., Zagazig University, Egypt

* Corresponding author. Tel.: +20 1008444985, Fax: +202 22911118

E-mail address: [email protected] (T. A EL-SAYED*)

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COMPARISON BETWEEN FLAT SLAB AND SOLID SLAB SYSTEMS

IN STRESSES DISTRIBUTION UNDER THE FOUNDATION USING

FINITE ELEMENT ANALYSIS

M. E. EL KILANY1, T. A. EL-SAYED2*, N. R. EL-SAKHAWY3, A. I. EL-DOSOKY4

1Associate Professor, Civil Str. Eng. Dep., Faculty of Eng., Zagazig University, Egypt 2Assistant Professor, Civil Str.Eng. Dep., Shoubra Faculty of Eng., Benha University, Egypt

3Professor, Civil Str. Eng. Dep., Faculty of Eng., Zagazig University, Egypt 4M.Sc Candidate, Civil Str. Eng. Dep., Faculty of Eng., Zagazig University, Egypt

ABSTRACT

Soil structure interaction is interdisciplinary field which includes auxiliary and

geotechnical engineering. In the ordinary non- interaction examination of building frame

structural designer assumed that columns are resting on unyielding support. So also, in

foundation design, foundation settlements are calculated without considering the impact of

the structural stiffness. The sub-grade reaction modulus "Ks" can be considered as a

fitting interface between the geotechnical and structural architects. The present research

studies the effect of statical systems of slabs (flat slab & solid slab) on the columns loads

distribution to achieve uniform stresses distribution under the foundation using finite

element analysis program sap 2000.

KEYWORDS

Soil structure interaction, Stresses distribution, modulus of sub grade reaction "Ks", structural analysis, SAP2000, static loading.

1. INTRODUCTION

A few studies have been made on the impact of soil-structure cooperation issues to get

more reasonable examination. They have evaluated the impact of connection conduct and

built up that there is redistribution of strengths in the structure and soil mass.

Consequently, structures and their supporting soils ought to be considered as a solitary

perfect unit. The connection impacts are discovered very noteworthy, especially for the

structures laying on exceptionally compressible soils. The adaptability of soil mass causes

the differential settlement and turn of footings under the use of burden.

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The interaction behavior of plane frames with an elastic foundation of the Winkler’s type,

having normal and shear moduli of sub-grade reactions is studied by Aljanabi et al. [1].

An exact stiffness matrix for a beam element on an elastic foundation having just a normal

modulus of sub-grade reaction was changed to include the shear modulus of sub-grade

reaction of the foundation and additionally the axial force in the beam. The outcomes

showed that bowing minutes may be significantly influenced by kind of edge and

stacking.

The proficiency of the coupled finite-infinite elements formulation regarding

computational exertion, information arrangement and the far field representation of the

unbounded area is explored by Noorzaei [2]. Al-Shamrani and Al-Mashary [3] displayed a

streamlined strategy for the investigation of soil-structure interaction behavior of two-

dimensional skeletal steel or reinforced concrete frame structures laying on isolated

footings that are supported by various sorts of soil. The principle program was made of

two noteworthy modules; one for soil settlement computations and another for the

investigation of structure. They assessed the impact of interaction on the predicted

settlements, footing loads, and internal bending moments of the structural members. Roy

et al. [4] performed an examination on an admired model comprising of multi-storey 3-D

frame structure with grid foundation. The grid foundation is assumed to lay on springs,

which romanticize the soil behavior.

The impact of soil-structure interaction on a space frame laying on a pile group installed in

the cohesive soil (clay) with flexible cap is analyzed by Chore et al. [5]. They assessed the

impacts of pile spacing, pile configuration, and pile diameter of the pile group on the

reaction of superstructure. The impact of soil structure interaction is observed to be very

huge.

The impact of contact between strap beam and bearing stratum is examined by Guzman

[6]. The outcomes demonstrate that when a strap footing is utilized as major of a

foundation system, a point of interest that take into consideration pressure to be alleviated

from the strap beam is vital on construction documents. Without it, an impressive

unanticipated load path made that may bring about the result in the failure of strap beam

followed by overstress of the soil under the eccentric footing.

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The interaction and non-interaction examinations for the space frame-raft foundation-soil

system utilizing ANSYS finite element code is compared by Thangaraj and Ilamparuthi

[7]. The soil was dealt with as an isotropic, homogenous and elastic half space medium. A

gritty parametric study was directed by shifting the soil and raft stiffness for a constant

building stiffness. The interaction examination demonstrated less total and differential

settlements than the non-interaction analysis and relative stiffness of soil plays significant

role in the execution of the raft. The stress and settlement distribution of a tank foundation

by using the finite element analysis software (ANSYS) is considered by Xiujuan et al. [8].

2. NUMERICAL STUDIES

2.1 Computer Analysis for Mat Foundation [9, 10]

Computer analysis for mat foundation is usually based on an approximation where the mat

is divided into a number of discrete finite elements using grid lines. There are three

general discrete element formulations which may be used:

1- Finite Difference (FD).

2- Finite Grid Method (FGM).

3- Finite Element Method (FEM).

All three of these methods use the modulus of sub grade reaction k, as the soil contribution

to the structural model. Computers and available software make the use of any of the

discrete element methods economical and rapid.

2.2 Finite Element Analysis (Sap 2000) [9, 10]

2.2.1 Shell Element

The six faces of a shell element are defined as the positive 1 face, negative 1 face, positive

2 face, negative 2 face, positive 3 face and negative 3 face as shown in Fig. 2.1. In this

definition the numbers 1, 2 and 3 correspond to the local axes of the shell element. [9, 10]

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Note that the positive 3 face is sometimes called the top of the shell element in SAP2000

and the negative 3 face is called the bottom of the shell element.

2.2.2 Frame Element Internal Forces and Moments [9, 10]

The frame element internal forces and moments are present at every cross-section along

the length of the frame. For each load pattern and load combination the frame internal

forces and moments are computed and reported at each frame output station as following:

1- P, the axial force

2- V2, the shear force in the 1-2 plane

3- V3, the shear force in the 1-3 plane

4- T, the axial torque (about the 1-axis)

5- M2, the bending moment in the 1-3 plane (about the 2-axis)

6- M3, the bending moment in the 1-2 plane (about the 3-axis).

3. VARIABLES OF THE STUDY

Table 1 summarizes the variable studied in this research. 3.1 Models Geometries and Statical Systems Figure 1 to Figure 3 show models geometries and dimensions. Models consist of two

equal spans in the both directions 10 m x 10 m, supported by 9 columns with dimensions

40 cm × 40 cm. There are two statical systems employed in this research: the first one is

flat slab with variable slab thickness, the second system is solid slab with constant slab

thickness 20 cm and each bay is surrounded by beams with width 30 cm and variable

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depth. Both systems are constructed on a square mat foundation with dimensions 10 m x

10 m with variable thickness. The mat will be founded at 1.5 m below the original ground

level.

3.2 Number of Stories

This research includes two types of models with constant story height 3.0 m and different

number of stories as fellows:

1- Five stories model with solid slab system.

2- Five stories model with flat slab system.

3- Ten stories model with solid slab system.

4- Ten stories model with flat slab system.

3.3 Structure Elements Dimensions 3.3.1 Raft Thickness 1- In models consist of five stories, raft thickness is variable from (40 cm = span/12.5) to

(100 cm = span/5).

2- In models consist of ten stories, raft thickness is variable from (80 cm = span/8.33) to

(140 cm = span/3.57).

3.3.2 Columns Dimensions

In all models, columns dimensions are constant and equal 40 cm x 40 cm

(span/12.5 in the both direction).

3.3.3 Slab Thickness 1- In models with flat slab system, slab thickness is variable from (18 cm = span/27.78) to

(30 cm = span/16.67).

2- In models with solid slab system, slab thickness is constant and equal 20 cm (span/25).

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3.3.4 Beams Depth 1- In models with flat slab system, there are no beams.

2- In models with solid slab system, beams depths is variable from (40 cm = span/12.5) to

(100 cm = span/5).

3.4 Applied Loads and Load Combinations In this research, Loads are uniform and constant in all stories for all models. Own weight

is taken into consideration, covering load is 3.0 KN/m2 and live load is 2.0 KN/m2.

Columns reactions are computed by combination: (1.0 own weight + 1.0 covering load +

1.0 live load).

3.5 Springs Constant

The modulus of sub grade reaction "Ks" is used to compute node springs based on the

contributing plan area of an element to any node.

Where: (Joint spring = Modulus of sub grade reaction x area) As follows:

1- Interior node springs = Ks x (0.50x0.50).

2- Edge node springs = Ks x 0.50 x (0.50x0.50).

3- Corner node springs = Ks x 0.25 x (0.50x0.50).

3.6 Soil Types One type of soil is employed in this research. The description and properties of the soil are

summarized in Table 2. "Vesic" relation is the governing relation for estimating "Ks" in

our study [11]. Substituting υs (poisson,s ratio) = 0.3, B (footing width) = 10 m, EcIc

(flexural rigidity of the raft) =2.50×1010 kN.m2 [12] and Es (soil modulus of elasticity) =

300578 KPa [13].

…………….equation (1) [11]

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4. RESULTS AND ANALYSIS Columns loads (corner, edge, internal column) are computed and compared in all models

as variation in column load can be consider as an indication to the same variation in

stresses under this column because raft dimensions and meshing are constant and equal

for all models. ℴ (stresses) = P (column load) /A (area), i.e (ℴα P).

Tables and charts give the relation between relative columns loads (computed sap

column load / column load computed by area method) and relative element dimensions

(maximum span / element dimension) in order to make general relation related to

maximum span in the building and try to achieve the same column load computed by area

method and getting uniform stresses under the foundation.

4.1 Models Consist of 5 Stories with Solid Slab System

Figures from 4 to 6 show the effect of increase the raft thickness from 40 cm to 100 cm

and increase the beams depth from 40 cm to 100 cm on the columns loads in models of

five stories with solid slab system.

Figure 4 indicate that corner column load decrease by 9% when beams depth increase

from 40 cm to 100 cm in models with raft thickness 40 cm and decrease by 12% in

models with raft thickness 60 cm and decrease by 9% in models with raft thickness 80 cm

and decrease by 7% in models with raft thickness 100 cm. Corner column load increase

by 10% at beams depth 40 cm when raft thickness increase from 40 cm to 100 cm and

increase by 12% at beams depth 100 cm.

Figure 5 indicate that there is an insignificant difference in edge column load when

beams depth increase from 40 cm to 100 cm in all models. Edge column load increase by

1% at beams depth 40 cm when raft thickness increase from 40 cm to 100 cm and

increase by 5% at beams depth 100 cm.

Figure 6 indicate that there is no difference in internal column load when beams depth

increase from 40 cm to 100 cm in models with raft thickness 100 cm. They also clears

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that internal column load increase by 12% when beams depth increase from 40 cm to 100

cm in models with raft thickness 40 cm and increase by 8% in models with raft thickness

60 cm and increase by 4% in models with raft thickness 80 cm. Internal column load

decrease by 15% at beams depth 40 cm when raft thickness increase from 40 cm to 100

cm and decrease by 27% at beams depth 100 cm.


on the stresses distribution under the foundation in models consist of five stories with

solid slab system at beams depths equal 40 cm. Figure 7 and Figure 10 indicate that soil

stresses changed from (from 52 KN/m2 to 138 KN/m2) in model with raft thickness 40 cm

to (from 80 KN/m2 to 99 KN/m2) in model with raft thickness 100 cm which mean that

maximum soil stress decrease by 28.26 %.


on the stresses distribution under the foundation in models consist of five stories with

solid slab system when beams depths equal 100 cm. Figure 11 and Figure 14 indicate that

soil stresses changed from (from 63 KN/m2 to 152 KN/m2) in model with raft thickness 40

cm to (from 92 KN/m2 to 115 KN/m2) in model with raft thickness 100 cm which mean

that maximum soil stress decrease by 24.34%.

4.2 Models Consist of 10 Stories with Solid Slab System


and increase the beams depth from 40 cm to 100 cm on the columns loads in models of ten

stories with solid slab system.

Figure 15 indicate that corner column load decrease by 7% when beams depth increase

from 40 cm to 100 cm in models with raft thickness 80 cm and decrease by 3% in models

with raft thickness 100 cm and increase by 4% in models with raft thickness 140 cm. They

also clears that there is an insignificant difference in corner column load when beams

depth increase from 40 cm to 100 cm in models with raft thickness 120 cm. Corner

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column load increase by 13% at beams depth 40 cm when raft thickness increase from 80

cm to 140 cm and increase by 24% at beams depth 100 cm.


beams depth increase from 40 cm to 100 cm in all models. Edge column load decrease by

2% at beams depth 40 cm when raft thickness increase from 80 cm to 140 cm and

decrease by 5% at beams depth 100 cm.

Figure 17 indicate that there is an insignificant difference in internal column load when

beams depth increase from 40 cm to 100 cm in models with raft thickness 80 cm and 100

cm. They also clears that internal column load decrease by 5% when beams depth increase


with raft thickness 140 cm. Internal column load decrease by 11% at beams depth 40 cm

when raft thickness increase from 80 cm to 140 cm and decrease by 20% at beams depth

100 cm.


on the stresses distribution under the foundation in models consist of ten stories with solid

slab system when beams depths equal 40 cm. Figure 18 and Figure 21 indicate that soil

stresses changed from (from 123 KN/m2 to 195 KN/m2) in model with raft thickness 80




on the stresses distribution under the foundation in models consist of ten stories with solid

slab system when beams depths equal 100 cm. Figure 22 and Figure 25 indicate that soil




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4.3 Models Consist of 5 Stories with Flat Slab System


and increase the slab thickness from 18 cm to 30 cm on the columns loads in models of

five stories with flat slab system.

Figure 26 indicate that there is an insignificant difference in corner column load when slab

thickness increase from 18 cm to 30 cm in all models. Corner column load increase by 2%

at slab thickness 18 cm when raft thickness increase from 40 cm to 100 cm and increase

by 4% at slab thickness 30 cm.

Figure 27 indicate that there is an insignificant difference in edge column load when slab

thickness increase from 18 cm to 30 cm in all models. Edge column load increase by 2%

at slab thickness 18 cm when raft thickness increase from 40 cm to 100 cm and increase

by 4% at slab thickness 30 cm.

Figure 28 indicate that there is no difference in internal column load when slab thickness

increase from 18 cm to 30 cm in models with raft thickness 40 cm. They also clears that

internal column load decrease by 3% when slab thickness increase from 18 cm to 30 cm in

models with raft thickness 60 cm and decrease by 6% in models with raft thickness 80 cm

and decrease by 9% in models with raft thickness 100 cm. Internal column load decrease

by 5% at slab thickness 18 cm when raft thickness increase from 40 cm to 100 cm and

decrease by 14% at slab thickness 30 cm.


on the stresses distribution under the foundation in models consist of five stories with flat

slab system when slab thickness equal 18 cm. Figure 29 and Figure 32 indicate that soil

stresses changed from (from 45 KN/m2 to 110 KN/m2) in model with raft thickness 40 cm

to (from 72 KN/m2 to 83 KN/m2) in model with raft thickness 100 cm which mean that

maximum soil stress decrease by 24.54%.

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Figure 33 and Figure 36 show the effect of increase the raft thickness from 40 cm to 100

cm on the stresses distribution under the foundation in models consist of five stories with

flat slab system when slab thickness equal 30 cm. Figure 33 and Figure 36 indicate that

soil stresses changed from (from 56 KN/m2 from 133 KN/m2) in model with raft thickness

40 cm to (from 85 KN/m2 from 100 KN/m2) in model with raft thickness 100 cm which

mean that maximum soil stress decrease by 24.81%.

4.4 Models Consist of 10 Stories with Flat Slab System Figures from 37 to 39 show the effect of increase the raft thickness from 80 cm to 140 cm

and increase the slab thickness from 18 cm to 30 cm on the columns loads in models of

ten stories with flat slab system.

Figure 37 indicate that corner column load increase by 6% when slab thickness increase

from 18 cm to 30 cm in models with raft thickness 80 cm and increase by 10% in models

with raft thickness 100 cm and increase by 12% in models with raft thickness 120 cm and

increase by 14% in models with raft thickness 140 cm. Corner column load increase by

2% at slab thickness 18 cm when raft thickness increase from 80 cm to 140 cm and

increase by 10% at slab thickness 30 cm.

Figure 38 indicate that there is an insignificant difference in edge column load when slab

thickness increase from 18 cm to 30 cm in all models. They also clears that there is no

difference in edge column load when raft thickness increase from 80 cm to 140 cm in all

models.

Figure 39 indicate that internal column load decrease by 11% when slab thickness increase


with raft thickness 100 cm and decrease by 17% in models with raft thickness 120 cm and

decrease by 18% in models with raft thickness 140 cm. Internal column load decrease by

4% at slab thickness 18 cm when raft thickness increase from 80 cm to 140 cm and

decrease by 11% at slab thickness 30 cm.

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on the stresses distribution under the foundation in models consist of ten stories with flat

slab system. Figure 40 and Figure 43 indicate that soil stresses changed from (from 110

KN/m2 to 154 KN/m2) in model with raft thickness 80 cm to (from 132 KN/m2 to 145

KN/m2) in model with raft thickness 140 cm which mean that maximum soil stress

decrease by 5.84 %.


on the stresses distribution under the foundation in models consist of ten stories with flat

slab system when slab thickness equal 30 cm. Figure 44 and Figure 47 indicate that soil



that maximum soil stress decrease by 9.09 %.

4.5 Comparison between Models Consist of 5 Stories and Models Consist

of 10 Stories with Solid Slab System

Figures from 48 to 50 show the comparison between columns loads in models consist of

five stories and models consist of ten stories with solid slab system at raft thickness 80 cm

and 100 cm and beam depth increase from 40 cm to 100 cm.

Figure 48 indicate that corner column load increase by 7% with raft thickness 80 cm at

beam thickness 40 cm and increase by 9% at beam thickness 100 cm and increase by 9%

in models with raft thickness 100 cm at beam thickness 40 cm and increase by 13% at

beam thickness 100 cm.


number of stories increase from 5 stories to 10 stories in models with raft thickness 80 cm

and 100 cm when beam thickness increase from 40 cm to 100 cm.

Figure 50 indicate that internal column load decrease by 11% with raft thickness 80 cm at

beam thickness 40 cm and decrease by 13% at beam thickness 100 cm and decrease by

13% in models with raft thickness 100 cm at beam thickness 40 cm and decrease by 15%

at beam thickness 100 cm.

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4.6 Comparison between Models Consist of 5 stories and Models Consist

of 10 Stories with Flat Slab System

Figures from 51 to 53 show the compare between columns loads in models consist of five

stories and models consist of ten stories with flat slab system at raft thickness 80 cm and

100 cm and slab thickness increase from 18 cm to 30 cm.

Figure 51 indicate that corner column load increase by 3% with raft thickness 80 cm at

slab thickness 18 cm and increase by 9% at slab thickness 30 cm and increase by 3% in

models with raft thickness 100 cm at slab thickness 18 cm and increase by 12% at slab

thickness 30 cm.

Figure 52 indicate that edge column load increase by 3% with raft thickness 80 cm at slab

thickness 18 cm and increase by 2% at slab thickness 30 cm and increase by 3% in models

with raft thickness 100 cm at slab thickness 18 cm and increase by 2% at slab thickness 30

cm.

Figure 53 indicate that internal column load decrease by 10% with raft thickness 80 cm at

slab thickness 18 cm and decrease by 15% at slab thickness 30 cm and decrease by 11% in

models with raft thickness 100 cm at slab thickness 18 cm and decrease by 16% at slab

thickness 30 cm.

5. CONCLUSION

1- In case of building consists of stories five stories and solid slab system:

a) Increasing beams depths from 40 cm to 100 cm leads to decrease in corner columns

loads by (7%: 12%) and increase in internal column load by (0%: 12%) but it have no

effect on edge columns loads.

b) Increasing raft thickness from 40 cm to 100 cm leads to increase in corner columns loads

by (10%: 12%), increase in edge columns loads by (1%: 5%) and decrease in internal

column load by (15%: 27%).

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c) Increasing raft thickness from 40 cm to 100 cm leads to decrease the maximum soil

stress under the foundation by (24.4 %: 28.3%).

d) Beams depths must be small as it can be and according to structure requirements.

e) Raft thickness must be at least equal (span/6) and it is prefer to increase raft thickness to

get uniform stresses distribution under the foundation.

2- In case of building consists of stories ten stories and solid slab system:

a) Increasing beams depths from 40 cm to 100 cm leads to change in corner columns loads

from decrease by 7% to increase by 4% and decrease in internal column load by (1%:

7%) but it have no effect on edge columns loads.


by (13%: 24%), decrease in edge columns loads by (2%: 5%) and decrease in internal

column load by (11%: 20%).



d) Beams depths must be small as it can be and according to structure requirements when

raft thickness less than (span/5) but when raft thickness is bigger than that it is prefer to

increase beams depths to get uniform stresses distribution under the foundation.

e) Raft thickness must be at least equal (span/4) and it is prefer to increase raft thickness to

get uniform stresses distribution under the foundation.

3- In case of building consists of stories five stories and flat slab system:

a) Increasing slab thickness from 18 cm to 30 cm leads to decrease in internal columns

loads by (0%: 9%) but it have no effect on corner and edge columns loads.

b) Increasing raft thickness from 40 cm to 100 cm leads to increase in corner and edge

columns loads by (2%: 4%) and decrease in internal column load by (5%: 14%).

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4- In case of building consists of stories ten stories and flat slab system:

a) Increasing slab thickness from 18 cm to 30 cm leads to increase in corner columns loads

by (6%: 14%) and decrease in internal columns loads by (11%: 18%) but it have no

effect on edge columns loads.


by (2%: 10%) and decrease in internal column load by (4%: 11%) but it have no effect

on edge columns loads.



5- Effect of increase the raft thickness on stresses distribution under the foundation is bigger

on buildings with average number of stories five stories than buildings with average number

of stories ten stories.

6- Increase beams depths have an insignificant effect on stresses distribution under the

foundation in case of buildings with solid slab system.

7- Effect of increase slab thickness on stresses distribution under the foundation in case of

buildings with flat slab system is bigger on buildings with average number of stories ten

stories than buildings with average number of stories five stories.

6. REFERENCES

1- A.I.M. Aljanabi, B.J.M. Farid, and A.A.A. Mohamed, Interaction of plane frames with

elastic foundation having normal and shear moduli of subgrade reactions, Comput.

Struct., 36(6), 1990, 1047-1056.

2- J. Noorzaei, Concepts and application of three dimensional infinite elements to soil-

structure-interaction problems, Int. J. Eng., 9(3), 1996, 131-142.

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3- M.A. Al-Shamrani, and F.A. Al-Mashary, A simplified computation of the interactive

behavior between soils and framed structures, Eng. Sci., 16(1), 2003, 37-60.

4- R. Roy, K. Bhattacharya, and S.C. Dutta, Behaviour of grid foundation under static

gravity loading, J. Inst. Eng. (India), 85, 2005, 261-268.

5- H.S. Chore, R.K. Ingle, and V.A. Sawant, Building frame - pile foundation - soil

interaction analysis: a parametric study, J. Interact. Multiscale Mech., 3(1), 2010, 55-79.

6- T. Guzman, Heavily loaded strap footing-design, detailing and behavior, Structure

Magazine, 2010, 12-15.

7- D. Thangaraj and K. Ilamparuthi, Parametric study on the performance of raft foundation

with interaction of frame, Electron. J. Geotech. Eng., 15, 2010, 861-878.

8- Y. Xiujuan, X. Zongxiang, Z. Lisong, and Y. Xiangzhen, 3D simulation of weak

foundation for good-sized oil storage tank, Proc. of International Conference on

Mechanic Automation and Control Engineering, China, 2010, 1345-1348.

9- Sap-2000 (V.16) User's Manual, Computers and Structures, Inc.1995 University Avenue,

Berkeley, California 94704, USA.

10- T. A. El-sayed, m. E. El kilany, n. R. El-sakhawy and a. I. El-dosoky , 2016. Methods for

achievement uniform stresses distribution under the foundation, international journal of

civil engineering & technology (ijciet).volume:7, issue: 2, pages: 45-66.

11- Jamshid and Maryam, 2009. Comparative Study of Methods of Determination of

Coefficient of Subgrade Reaction, electronic journal of geotechnical engineering. Volume

14- Bundle E.

12- Egyptian code for Reinforced concrete (ECCS – 203 - 2001) REV.02 – chapter 06 –

Foundation design - Egypt.

13- Bowles (1997) "Foundation Analysis and Design" Text book - International Edition -

McGraw-Hill Book Co. - Singapore.

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Table 1: Research Variables

Table 2: Soil properties and descriptions

Soil Type Soil description Es

(KPa)

Bearing capacity

B/C (KN/ m2)

Modulus of Sub

grade Reaction

Ks (KPa)

Type (1) Medium Dense Sand 300578 220 18000

Soil Type Type (1)

Slab System Flat Slab Solid Slab

Slabs Thicknesses 18 : 30 cm 20 cm

Beams Depths ——— 40 : 100 cm

Number of Stories 10-Stories 5-Stories 10-Stories 5-Stories

Raft Thickness 80 : 140 cm 40 : 100 cm 80 : 140 cm 40 : 100 cm

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Figure 1: Flat slab system

Figure 2: Solid slab system

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Figure 3: Raft system and dimensions

Figure 4: Corner column load in models consist of 5 stories with solid slab system

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Figure 5: Edge column load in models consist of 5 stories with solid slab system

Figure 6: Internal column load in models consist of 5 stories with solid slab system

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Figure 7: Soil stresses distribution in model with beam Figure 8: Soil stresses distribution in model with beam depth 40 cm & raft thickness 40 cm & solid slab & 5 stories depth 40 cm & raft thickness 60 cm & solid slab & 5 stories


Figure 11: Soil stresses distribution in model with beam Figure 12: Soil stresses distribution in model with beam Depth 100 cm & raft thickness 40 cm & solid slab & 5 stories depth 100 cm & raft thickness 60 cm & solid slab & 5 stories

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Figure 15: Corner column load in models consist of 10 stories with solid slab system

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Figure 16: Edge column load in models consist of 10 stories with solid slab system

Figure 17: Internal column load in models consist of 10 stories with solid slab system

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Figure 26: Corner column load in models consist of 5 stories with flat slab system

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Figure 27: Edge column load in models consist of 5 stories with flat slab system

Figure 28: Internal column load in models consist of 5 stories with flat slab system

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Figure 29: Soil stresses distribution in model with slab Figure 30: Soil stresses distribution in model with slab thickness 18 cm & raft thickness 40 cm & flat slab & 5 stories thickness 18 cm & raft thickness 60 cm & flat slab & 5 stories



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Figure 37: Corner column load in models consist of 10 stories with flat slab system

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Figure 38: Edge column load in models consist of 10 stories with flat slab system

Figure 39: Internal column load in models consist of 10 stories with flat slab system

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Figure 40: Soil stresses distribution in model with slab Figure 41: Soil stresses distribution in model with slab thickness 18 cm & raft thickness 80 cm & flat slab &10 stories thickness 18 cm & raft thickness 100 cm& flat slab &10 stories

Figure 42: Soil stresses distribution in model with slab Figure 43: Soil stresses distribution in model with slab thickness 18 cm & raft thickness 120 cm & flat slab&10 stories thickness 18 cm&raft thickness 140 cm&flat slab & 10 stories

Figure 44: Soil stresses distribution in model with slab Figure 45: Soil stresses distribution in model with slab thickness 30 cm & raft thickness 80 cm & flat slab &10 stories thickness 30 cm & raft thickness 100 cm&flat slab & 10 stories

114 Jokull Journal

Vol 66, No.12;Dec 2016

Figure 46: Soil stresses distribution in model with slab Figure 47: Soil stresses distribution in model with slab thickness 30 cm & raft thickness 120cm&flat slab&10 stories thickness 30 cm & raft thickness 140 cm & flat slab & 10 stories

Figure 48: Comparison between corner column load in models consist of 5 stories and models consist of 10 stories with solid slab system

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Vol 66, No.12;Dec 2016

Figure 49: Comparison between edge column load in models consist of 5 stories and models consist of 10 stories with solid slab system

Figure 50: Comparison between internal column load in models consist of 5 stories and models consist of 10 stories with solid slab system

116 Jokull Journal

Vol 66, No.12;Dec 2016

Figure 51: Comparison between corner column load in models consist of 5 stories and models consist of 10 stories with flat slab

Figure 52: Comparison between edge column load in models consist of 5 stories and models consist of 10 stories with flat slab system

117 Jokull Journal

Vol 66, No.12;Dec 2016

Figure 53: Comparison between internal column load in models consist of 5 stories

and models consist of 10 stories with flat slab system

COMPARISON BETWEEN FLAT SLAB AND SOLID SLAB · PDF filecomparison between flat slab and solid...

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