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Investigating the Effect of Solid and Lightweight Hollow Block Slabs on

Construction Cost

Article  in  Management Procurement and Law · January 2019

DOI: 10.1680/jmapl.17.00054

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Cite this articleBikçe M, Akyol B and Resatoglu RInvestigating the effect of solid and lightweight hollow block slabs on construction cost.Proceedings of the Institution of Civil Engineers – Management, Procurement and Law,https://doi.org/10.1680/jmapl.17.00054

Research ArticlePaper 1700054Received 16/10/2017; Accepted 18/01/2019

Published with permission by the ICE under theCC-BY 4.0 license.(http://creativecommons.org/licenses/by/4.0/)

Keywords: buildings, structures &design/concrete structures/slabs & plates

Management, Procurement and Law

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Investigating the effect of solid andlightweight hollow block slabs onconstruction cost

Murat BikçeDepartment of Civil Engineering, Faculty of Engineering and NaturalSciences, İskenderun Technical University, İskenderun, Turkey(corresponding author: murat.bikce@iste.edu.tr)(Orcid:0000-0001-5529-2387)

[] on [20/02/19]. Published with permission by the ICE under the CC-BY licens

Bünyamin AkyolDepartment of Civil Engineering, Faculty of Engineering and NaturalSciences, İskenderun Technical University, İskenderun, Turkey

Rifat ResatogluDepartment of Civil Engineering, Faculty of Civil and EnvironmentalEngineering, Near East University, Nicosia, Northern Cyprus

In the design of reinforced-concrete buildings, solid and lightweight hollow block slabs are commonly preferred. Ingeneral, it is believed that the cost of lightweight hollow block slabs is higher than that of solid slabs. This researchaims to examine the effect of solid and lightweight hollow block slabs on construction cost both in a parametricstudy and in actual buildings. In the parametric study, both the x and y directions included a variation of two to fourspacings, while on the vertical plane an increase up to ten floors has been taken into account, and accordinglyconstruction costs have been compared. Then, ten structures which have solid slabs, whose number of floors was upto ten and which had been designed in accordance with updated earthquake regulations, were chosen to obtain thecost difference when designed with lightweight hollow block slabs. In all examinations, it has been confirmed thatlightweight hollow block slabs cost more than solid slabs, creating a 10·49–21·93% cost difference ratio, and that thecost difference ratios obtained from the actual structures also agree with these findings. The study presents increasecurves depending on the slab type, modal analyses and strength comparisons.

Notationd thickness of slabG dead loadI building importance coefficientQ live loadTa, Tb spectrum characteristic periodsVx shearing force in x directionVy shearing force in y direction

1. IntroductionSlabs that transmit both vertical load and horizontal load such asearthquakes to the vertical bearing elements of a structure aregenerally considered two dimensional, for slab thicknesses can bedisregarded compared to the other two dimensions. Since slabssupport the rigid diaphragm action, the floors provide equaldisplacement and rotation in the analysis (Park and Gamble,1995: p. 711; Punmia, 2005: p. 847).

In reinforced-concrete buildings, a solid slab is a conventional slabwhich is supported by beams and columns, with the load transferredto those elements. This slab type (Figure 1(a)) is classified as eitherone-way or two-way. The other slab type is a ribbed floor slabconsisting of equally spaced ribs, usually supported directly bycolumns. Slabs are either one-way spanning systems or two-waysystems. When the space between beams is filled with lightweightmaterial, they are called lightweight hollow block slabs; the othercommonly used name is hordy slab (Figure 1(b)). Hollow blocksare used to fill portions of the slab thickness; this results in a deeperarm for the reinforcement while reducing the amount of concrete

and hence the self-weight of the slab. The reinforcement is locatedbetween the blocks inside the ribs. A block may be a concreteblock, a briquette or styrofoam. When the ribs are in one direction,then it is a one-way hollow block slab, regardless of therectangularity. When the ribs are in both directions, then it is a two-way hollow block slab. This type of slab has longitudinal voidsrunning through it, which decrease the weight of the slab, as well asthe amount of concrete required. These voids can also function asservice ducts. A two-way hollow block slab is generally reinforcedwith longitudinal rebar and can achieve long spans, making itsuitable for office buildings, multistorey car parks and so on(Fanella and Alsamsam, 2005). In order to make comparisonamong the two type of slabs possible, the most common residentialbuilding model has been chosen in this paper. Despite theirdisadvantages, there are certain reasons why lightweight hollowblock slabs are widely used, such as their ability to fill big spaceseasily, lower formwork cost and smooth surface on ceilings, therebyallowing flexible choice of where to place an interior wall. Anothertype of slab is the flat slab, which is supported directly by columnswithout the use of beams. Both vertical and horizontal loads aretransferred directly from slab to columns. This type of slab is not ascommon as the other two types mentioned earlier.

Solid slab systems are known to affect structural ductilitybecause of high diaphragm rigidity, necessary lateral resistanceand translational rigidity, and to have an impact on the resultsof modal analyses (Doǧangün, 2004; Lam et al., 1998; Matthews,2004: p. 523). Slabs behave rigidly in the direction of ribs; someproblems may be experienced regarding ensuring enough rigidity

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Management, Procurement and Law Investigating the effect of solid andlightweight hollow block slabs onconstruction costBikçe, Akyol and Resatoglu

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in a perpendicular position to ribs, since ribs do not fit into beamsin that direction.

The design of a structure must satisfy strength, stability andserviceability. Considering these requirements, it is important toresist safely the stresses which are induced by the loads. Thestructure must also be economical. Care should be taken to createa safe structure in the most economical way while forming thestructural system of the targeted structure (Choi et al., 2007).Since the earthquake loads acting on structures depend on thebuilding masses, lightweight hollow block slabs are subject tomore earthquake load than solid slabs. Therefore, structures withlightweight hollow block slabs require an increase in the size ofvertical bearing elements in order to keep the structures safeagainst relative floor displacement, which, in turn, affects theconstruction cost. The general opinion is that the cost oflightweight hollow block slabs is higher than that of solid slabs.However, with the temptation of architectural preferences, thecost increase is often tolerated. The cost increase ratio has beenstated to be in a wide range in research studies (Galeb and Atiyah,2011; Kaveh and Behnam, 2012) and on websites that captureengineers’ personal experiences (FYN, 2017; JLC, 2017). Theauthors have examined ten buildings with up to 16 floors, five ofthose buildings with lightweight hollow block slabs and the otherfive with solid slabs, which have been designed in accordancewith updated earthquake regulations. As a result of theexamination, it has been determined that the cost difference variesbetween 1·33 and 15·37% when one slab type is replaced withthe other (Bikçe and Akyol, 2017).

Engineers have a wide choice of concrete floor systems forbuildings. Different forms of slab constructions tend to result invariation in the cost of the slabs for any building project. For thisreason, structural engineers should pay more attention toalternatives in order to avoid having the same safety structure at ahigher cost, as the type of slabs directly affects the buildingcost. However, there is a widespread belief that lightweighthollow block slabs cost more compared to solid slabs. Advantagesand disadvantages of both lightweight hollow block slabs andsolid slabs can easily be found in the literature, while costcomparisons are encountered only on forum websites where the

2ed by [] on [20/02/19]. Published with permission by the ICE under the CC-BY l

designers’ specific experiences can be derived from a wide rangeof comments. There is no study about the rate of cost surplus. Noscientific study has been found regarding the cost surplus exceptfor the examination by the authors, although how the change inslab type would vary depending on the spacing and number offloors is still an interesting and undetermined subject. In thisstudy, the main objective is to compare solid slabs andlightweight hollow block slabs based on cost evaluation both in aparametric study and in actual buildings. The economiccomparison made in this study based on the change in the slabtype of a newly finished building is important in order to showdesigners the possibility of the same building being constructedfor lower or higher costs.

While investigating the effect of solid and lightweight hollow blockslab types on construction cost, a variation of two to four spacings inthe x and y directions and an increase up to ten floors in the verticalplane have been taken into account. The cost difference has beendetermined for the case when solid slabs in buildings of up to tenfloors are changed to lightweight hollow block slabs. Also, theresults of a modal analysis and changes in the shearing force for bothslab types have been analysed.

2. Selected structures and their analyticalmodels

2.1 Parametric investigationSeparate models have been prepared for both solid and lightweighthollow block slabs. In each model, the analyses have been repeated,ensuring minimum sections for both the x and y directions from oneto four spacings in the design. On the horizontal plane, a spacing ofup to four has been taken into account, and in the vertical plane,analyses have been repeated for an increase up to ten floors. For eachslab type, the spacings have been fixed to 5 × 5m. The images fromthe analysed models are presented in Figures 2(a) and 2(b) for thesolid slab type and in Figures 3(a) and 3(b) for the lightweighthollow block slab type.

2.2 Analysis of the actual buildingsIn order to reveal the cost difference, ten different buildingprojects complying with the updated earthquake regulation(Turkish Earthquake Code 2007 (MPWS, 2007)) and standard(TS 500 (TSE, 2000)) of up to ten floors and with solid slabswere chosen. The yield strength of the steel was set as 420MPa.There are two types of data used for the residential reinforced-concrete building design, which are general building data andcharacteristic building data for the investigated buildings asshown in Table 1. In order to change the slab type of the selectedbuildings from solid to lightweight hollow block, two models foreach building, one solid and one lightweight hollow block, weredesigned. As a result of the slab change, there were somedeficiencies in the bearing elements in accordance with theupdated regulation and standard. Thus the bearing elements wereenlarged or made smaller at an optimum level without putting inany additional elements or changing the structural statics in order

Solid slabFloor board

Rib

Fill material(a) (b)

Figure 1. (a) Solid slab type; (b) lightweight hollow block slab type

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to comply with the earthquake regulation. The aim is to reveal theminimum cost difference occurring as a result of changing theslab type of the buildings.

3. General information regarding theanalyses

The comparison of the minimum cost differences resulting fromthe conversion of the selected solid and lightweight hollow blockslab types is the aim of this study. Therefore, care has been takento ensure that necessary changes to the reduction or increase inthe cross-sectional dimensions of the bearing elements accordingto standards resulting from the conversion of slab types are keptat an optimum level. In order to reveal the cost difference, all

[] on [20/02/19]. Published with permission by the ICE under the CC-BY licens

other variables such as number of floors and material propertiesare kept constant while converting the slab types of theinvestigated buildings. In the design of lightweight hollow blockslabs, the height of ribs is limited to the level of the beams, andedge beams have been formed as commonly preferred widebeams. In the design, up-to-date and commonly used buildingmaterials have been preferred.

Briquettes are preferred to have sizes of 25 × 40 × 20 cm and areproduced from lightweight concrete and widely used in themarket as a filling material for lightweight hollow block slabs(ACI 318-05 code and commentary (ACI Committee 318, 2005)).In the analysed buildings, the coefficient of concrete safety is 1·5,

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G = 0·475 tf/m2 G = 0·475 tf/m2 G = 0·475 tf/m2 G = 0·475 tf/m2

Q = 0·2 tf/m2 Q = 0·2 tf/m2 Q = 0·2 tf/m2Q = 0·2 tf/m2

D08 D09 D10 D11d = 13

G = 0·475 tf/m2

Q = 0·2 tf/m2

D04d = 13

d = 13 d = 13 d = 13

G = 0·475 tf/m2

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D07d = 13

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D05d = 13

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Figure 2. (a) Sample solid slab type model with 2 × 4 spacing; (b) sample solid slab type model with 4 × 4 spacing (continued on next page)

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G = 0·475 tf/m2 G = 0·475 tf/m2 G = 0·475 tf/m2 G = 0·475 tf/m2

Q = 0·2 tf/m2 Q = 0·2 tf/m2 Q = 0·2 tf/m2Q = 0·2 tf/m2D16 D17 D18 D19

d = 13

G = 0·475 tf/m2

Q = 0·2 tf/m2D12

d = 13

G = 0·475 tf/m2

Q = 0·2 tf/m2D08

d = 13G = 0·475 tf/m2

Q = 0·2 tf/m2D09

d = 13G = 0·475 tf/m2

Q = 0·2 tf/m2D10

d = 13G = 0·475 tf/m2

Q = 0·2 tf/m2D11

d = 13

d = 13 d = 13 d = 13

G = 0·475 tf/m2

Q = 0·2 tf/m2D15

d = 13G = 0·475 tf/m2

Q = 0·2 tf/m2D14

d = 13G = 0·475 tf/m2

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d = 13

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d = 13

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(b)

x

y

Figure 2. Continued

4ed by [] on [20/02/19]. Published with permission by the ICE under the CC-BY license

Management, Procurement and Law Investigating the effect of solid andlightweight hollow block slabs onconstruction costBikçe, Akyol and Resatoglu

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the coefficient of steel safety is 1·15 and the concrete unit volumeweight is taken to be 2·5 t/m3. During the static and dynamicanalyses, the updated earthquake regulation and standard havebeen taken into account (MPWS, 2007; TSE, 2000). The up-to-date unit prices for materials considered in the cost comparisonare presented in Table 2.

In all elements, it has been presumed that the size and materialproperties do not change along the element. In the calculations, abuilding with 285 00MPa elasticity modulus of concrete, 0·2Poisson’s ratio and 420MPa outflow strength of steel has beenconsidered to be in the first-degree seismic zone, and the local

[] on [20/02/19]. Published with permission by the ICE under the CC-BY licens

soil class, as one of the parameters, has been selected as Z1(MPWS, 2007).

Reinforced-concrete buildings are analysed and designed using theideCad (2017) software package. ideCad (2017) is an integratedpackaged software program that can perform three-dimensionalanalysis. The analyses for both slab models have been repeated, andthe results provided from the software have been multiplied by theunit prices presented in Table 2 to get the building costs.

For the selected building in the parametric study, the slab size is 5 ×5m, the storey height is 3 m and the smallest size of a column is

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xy

Figure 3. (a) Sample lightweight hollow block slab type model with 2 × 4 spacing; (b) sample lightweight hollow block slab type modelwith 4 × 4 spacing (continued on next page)

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Figure 3. Continued

6ed by [] on [20/02/19]. Published with permission by the ICE under the CC-BY license

Management, Procurement and Law Investigating the effect of solid andlightweight hollow block slabs onconstruction costBikçe, Akyol and Resatoglu

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Table 1. General residential building data

[

NF

] on [20/02/19]. P

CG: MPa

ublished with permissi

BA: m

on by the ICE under

SZ

the CC-BY licen

FUW: t/m

se

CSR: t/m

ABP: t/m ST

1

25 252 2 2·2 4000 22 Z3 2 30 304 2 2·1 5500 20 Z2 3 25 451 1 2·2 4000 19 Z3 4 25 723 1 1·9 3500 19 Z3 5 25 902 1 2·1 6000 17 Z3 6 30 1315 4 2·0 2500 25 Z2 7 25 1726 1 2·1 4000 26 Z3 8 25 2516 4 2·0 7000 25 Z2 9 25 3043 4 2·1 9000 30 Z2 10 30 3416 4 2·1 2500 15·6 Z3

ABP, allowable bearing pressure; BA, building area; CG, concrete grade; CSR, coefficient of soil reaction; FUW, foundation unit weight; NF, number of floors; ST,soil type; SZ, seismic zone

Table 2. Current unit prices of building materials

Reinforcement: $/t

Concrete: $/m3 Briquettes: $/unit Formwork: $/m2 Labour cost: $/m3

431·31

30·35 0·32 4·15 25·6

4770 95

59 14 6

42

20 6

96

2651

3

33 5

39 42 0

27 50 1

91 57 9

40 67 0

29

4051 82

03 12 5

63

17 2

56

22 2

74

27 9

61 34 4

68 43 3

89 49 9

55

55 9

21

0

10 000

20 000

30 000

40 000

50 000

60 000

70 000

80 000

1 2 3 4 5Number of floors

Number of floors

(a)

6 7 8 9 10

Con

stru

ctio

n co

st: $ Lightweight

hollowblock slab

Solid slab

8951 18

119

2837

9

38 7

55

49 7

38 61 4

80 77 2

75 93 0

44 105

349

125

514

7557 15

396

23 6

19

32 4

94

42 0

33

52 1

75 66 1

38 80 0

97 95 3

47

109

602

0

20 000

40 000

60 000

80 000

100 000

120 000

140 000

1 2 3 4 5 6 7 8 9 10

Con

stru

ctio

n co

st: $

Lightweighthollowblock slab

Solid slab

(b)

Figure 4. (a) The cost curves of solid and lightweight hollow block slabs with 2 × 4 spacing; (b) the cost curves of solid and lightweighthollow block slabs with 4 × 4 spacing

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Management, Procurement and Law Investigating the effect of solid andlightweight hollow block slabs onconstruction costBikçe, Akyol and Resatoglu

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25 cm. For both slab types, the material feature of the structures isC25-S420. In addition, the earthquake parameters taken into accountin the analyses are as follows: the building importance coefficient(I ) 1, the eccentricity ratio 0·5, the earthquake zone 1 and the

8ed by [] on [20/02/19]. Published with permission by the ICE under the CC-BY l

effective ground acceleration coefficient 0·40. Also, the foundationparameters are as follows: soil class Z4, spectrum characteristicperiods Ta 0·20 and Tb 0·90, allowable bearing value 15 t/m2, soilpredominant period 0·25 s, coefficient of soil reaction 2500 t/m3 andsoil group A (MPWS, 2007; TSE, 2000). The infilled walls andcoating weight have not been taken into account in the design.

4. Cost comparisonsIn the parametric examination, analyses for both slab types of thestructures with the same number of floors have been carried out,and the graphs showing the cost differences are presented inFigures 4(a) and 4(b). The differences in construction methodsbetween different forms of slabs presented in the following figurestend to result in variation in the cost of the slabs. As clearlyshown in the figures, the cost of lightweight hollow block slabs ishigher than that of solid slabs.

In all of the buildings that have been analysed, lightweight hollowblock slabs cost more than solid slabs. The graph showing thecomparison ratio regarding the cost differences is provided inFigure 5.

Cost surplus ratios between lightweight hollow block slabs andsolid slabs were between 10·49 and 21·93% in the parametric

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10

Cos

t di

ffer

ence

: %

Number of floors

2 × 43 × 44 × 4Actual construction

Figure 5. Cost surplus ratios between lightweight hollow blockslabs and solid slabs in all buildings

(Solid slab) y = 19670x – 15663

(Ribbed slab) y = 22732x – 20420

0

10 000

20 000

30 000

40 000

50 000

60 000

70 000

80 000

0 1 2 3 4 5 6 7 8 9 10

Con

stru

ctio

n co

st: $

/m2

Number of floors(a)

Solid slabLightweight hollow block slabLinear (solid slab)Linear (lightweight hollow block slab)

(Solid slab) y = 37920x – 32717

(Ribbed slab) y = 41603x – 32016

0

20 000

40 000

60 000

80 000

100 000

120 000

140 000

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Figure 6. (a) The cost curves of solid and lightweight hollow block slabs with 2 × 4 spacing; (b) the cost curves of solid and lightweighthollow block slabs with 4 × 4 spacing

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Management, Procurement and Law Investigating the effect of solid andlightweight hollow block slabs onconstruction costBikçe, Akyol and Resatoglu

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study and 13·48–18·23% in the actual buildings. The fact that theratios for the actual buildings remain between the ratios obtainedfrom the parametric study demonstrates that the study isproportionately compatible.

The curve equations formulating the cost differences of the same typeof slabs according to the number of floors are presented in Figure 6.

5. Modal analysis and strength comparisonsAs a result of the modal analysis, the difference in periodsdepending on the difference in the slab type is demonstrated inFigure 7.

As can be seen in Figures 7(a) and 7(b), the buildings withlightweight hollow block slabs have reached higher periods

[] on [20/02/19]. Published with permission by the ICE under the CC-BY licens

compared to the ones with solid slabs. As a result of the changein the slab type, the change in the shearing force obtained at thecorner column base in the dynamic analysis is presented inFigures 8(a) and 8(b).

The buildings designed with lightweight hollow block slabs appear tohave higher shearing force values than the ones with solid slabs(Figures 8(a) and 8(b)). Also, as a consequence of the analyses, it hasbeen understood that this applies to the interior columns.

6. ConclusionsIn this study, the effect of solid and lightweight hollow blockslabs on construction cost both in a parametric study and in actualbuildings has been investigated. The study conveys the followingconclusions.

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Figure 7. (a) First three mode changes depending on the floors of solid and lightweight hollow block slabs with 2 × 4 spacing; (b) firstthree mode changes depending on the floors of solid and lightweight hollow block slabs with 4 × 4 spacing

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1 × A axis (Vy) (solid slab)1 × A axis (Vy) (lightweight hollow block slab)1 × A axis (Vx) (solid slab)1 × A axis (Vx) (lightweight hollow block slab)

Figure 8. (a) The change in shearing force of solid and lightweight hollow block slabs with 2 × 4 spacing; (b) the change in shearing forceof solid and lightweight hollow block slabs with 4 × 4 spacing

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Management, Procurement and Law Investigating the effect of solid andlightweight hollow block slabs onconstruction costBikçe, Akyol and Resatoglu

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■ In all of the cases examined, the cost of the building withlightweight hollow block slabs is more than the cost of thebuilding with solid slabs.

■ According to the results of the parametric study, it has beendetermined that lightweight hollow block slabs cost10·49–21·93% more than solid slabs. The examination of actualbuildings has also shown a similar ratio of cost differences.

■ The ratio of cost differences varies depending on not onlythe slab type, but also numerous other parameters suchas structural geometry, material properties, the number of floors,architectural obligations and most importantly the design of thestructures by engineers. Hence, in order to build a structure withthe same architecture and safety at a lower cost, it is essential toinvestigate alternative slab types.

■ It has been concluded that the buildings with lightweighthollow block slabs have reached higher periods and hadhigher shearing force values. Depending on the increase infloor weight of the hollow block slab, it is expected that thestructure’s relative storey displacements and period willincrease.

■ There has been a considerable increase in the numberof commercial buildings. Therefore, further studies are requiredto quantify and investigate the effects of different structuralsystems and configurations and occupancy types. It would beuseful for evaluating structural alternatives under differentseismic intensities and related cost-management studies.

AcknowledgementThe authors extend their thanks to the persons who have providedtheir support concerning the licence of ideCad used in this study.

REFERENCESACI Committee 318 (American Concrete Institute Committee 318) (2005)

ACI 318-05: Building code requirements for structural concrete andcommentary (ACI 318R-05). ACI, Farmington Hills, MI, USA.

10ed by [] on [20/02/19]. Published with permission by the ICE under the CC-BY l

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Bikçe M and Akyol B (2017) Tasarlanmış gerçek yapılarda asmolen/plakdöşeme dönüşümünün yapı maliyetine etkisi. Fırat ÜniversitesiMühendislik Bilimleri Dergisi 29(1): 133–144 (in Turkish).

Choi K, Park HG and Wight JW (2007) Unified shear strength model forreinforced concrete beams – part I: development. ACI StructuralJournal 4(2): 142–152, https://doi.org.org/10.14359/18526.

Doǧangün A (2004) Performance of reinforced concrete buildings duringthe May 1, 2003 Bingöl earthquake in Turkey. Engineering Structures26(6): 841–856.

Fanella DA and Alsamsam IM (2005) Design of Reinforced ConcreteFloor Systems. Portland Cement Association, Skokie, IL, USA.

FYN (Forum Yapısal Net) (2017) http://forum.yapisal.net/dosemeler/30472-asmolen-doseme-plak-doseme-maliyet-farki.html (accessed10/02/2017) (in Turkish).

Galeb AC and Atiyah ZF (2011) Optimum design of reinforced concretewaffle slabs. International Journal of Civil and Structural Engineering1(4): 862–880.

ideCad (2017) http://www.idecad.com.tr (accessed 10/02/2017) (in Turkish).JLC (Journal of Light Construction) (2017) http://forums.jlconline.com/

forums/forum/jlc-online-expert-forums/building-science/46816-raising-a-slab-floor-by-10 (accessed 10/02/2017).

Kaveh A and Behnam AF (2012) Cost optimization of a composite floorsystem, one-way waffle slab, and concrete slab formwork using acharged system search algorithm. Scientia Iranica 19(3): 410–416.

Lam D, Elliott KS and Nethercot DA (1998) Push-off tests on shear studswith hollow-cored floor slabs. The Structural Engineer 76(9):167–174.

Matthews J (2004) Hollow-core Floor Slab Performance following aSevere Earthquake. PhD thesis, Civil Engineering Department,University of Canterbury, Christchurch, New Zealand.

MPWS (Ministry of Public Works and Settlement) (2007) TurkishEarthquake Code 2007: Specification for structures to be built indisaster areas. MPWS, Government of Republic of Turkey, Istanbul,Turkey.

Park R and Gamble WL (1995) Reinforced Concrete Slabs. Wiley,Mississauga, ON, Canada.

Punmia BC (2005) Building Construction. Laxmi Publications, NewDelhi, India.

TSE (Turkish Standards Institute) (2000) TS 500: Requirements for designand construction of reinforced concrete structures. TSE, Ankara,Turkey.

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