IRJET- A Review on Effect of Different Set of Stiffness Modifiers Varying through Height of Struc

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A Review on Effect of Different Set of Stiffness Modifiers Varying Through Height of Structure on Analysis of Multi-Story R.C.C. Structure.

Mustafa E. Mithaiwala1, Prof. Amol A. Patil2, Dr. Navnath V. Khadake3 1PG

Student, Civil Engineering Department, JSPM’s ICOER Wagholi, Pune 412207, Maharashtra, India Professor, Civil Engineering Department, JSPM’s ICOER Wagholi, Pune 412207, Maharashtra, India 3HOD of Civil Engineering Department, JSPM’s ICOER Wagholi, Pune 412207, Maharashtra, India ---------------------------------------------------------------------***---------------------------------------------------------------------effective extensional stiffness, KN, of pre-cracked concrete Abstract – In current scenario many codes and researcher 2Assistant

panels orthogonally reinforced with No. 4 or No. 6 grade 60 R.C.C beams and subjected to uniaxial or biaxial tension.

These boards are intended to be illustrative of a fragment of a split control divider exposed to inside pressurization and get a relationship for the extensional stiffness, the all-out hub disfigurement surface was estimated toward applied strain power. The pressure hardening impact of cement was represented by evaluating a normal viable steel strain comparing to an identical without a cement concrete beam.

had suggested the stiffness modifiers value for the analysis of R.C.C. structure. As Stiffness is most important property any element which shows capacity of element to resist external force and solidness of an element. In this paper we had studied different values of stiffness modifier given by different researcher and codes for serviceability limit of the structure.

Key Words: Effective Stiffness, crack section properties, seismic design, linear analysis

Paulay [2001] [2] investigated on seismic designs and the ductile behaviors of horizontal force-resisting structural elements, and indeed the entire building structures can be adequately by simulating simple bi-linear forcedisplacement relationships. The relocation connections between the frameworks and their horizontal force opposing components created at a specific limit state to be promptly assessed. To this end, one should broadly utilize deceptions.

The progress from flexible to inelastic conduct was uncovered. Permits sensible forecasts of the hugest component of seismic reaction, component removals to be made. The ideas presented are objective however yet were straightforward. The technique gives the fashioners unforeseen opportunity in the task of qualities to a parallel power opposing components, for example, outlines or basic dividers. Despite current structure practice, whereby the fashioner can decide the adequate relocation request to be forced on the framework. This ought to secure basic components against exorbitant uprooting requests.

1. INTRODUCTION Stiffness of the member is most important properties for the analysis of the structure. the structural members of a building strongly affect the calculated response of the structure to ground movement. For linear analysis of members, member stiffness’s control forecasts of the period of the structure, the loads are distributed within the structure. For nonlinear analysis, we obtain a precise estimate of the associate stiffness that was required to estimate the yield displacement, which in turn, affects the translation ductility anxieties. Real-world, accurate procedures are needed to estimate the effective stiffness up to yielding of each structural component.

1.1 Limitation a.

To find actual reduction of stiffness is difficult as there are many reasons of formation of cracks.

b.

Cracking due to seismic shock are different for different configuration of structure and their age and there precise or well-established method for calculating reduction of stiffness of element.

Paulay [2002] [3] researched the recognizable proof of measures of execution based seismic design, for the center around estimations of uprooting limits of the flexible framework structure. This examination includes the redefinitions of certain properties of cement concrete structures. A framework containing parts with various attributes like a coupled divider structure was utilized to exhibit how dislodging and flexibility limit, fulfilling explicit execution rules, can be anticipated basically, even before the necessary seismic quality of the framework is set up An important feature of this method is that the strengths of components, which contribute to the required seismic strength of the system, can be freely chosen.

1.2 Advantages

We can incorporate approximately this effect of crack in structural analysis of R.C.C. Buildings to find responsible response of the structure

2. LITERATURE REVIEW Perdikaris et.al. [1985] [1] Investigated experimental data available regarding extensional stiffness in uni-axially or biaxially tensioned reinforced concrete elements. To improve our understanding of this important subject an experimental study was performed to determine an estimate for the

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Chan et.al. [2006] [4] explored R.C.C. building plans which fulfill usefulness stiffness measures as far as most extreme horizontal dislodging and between story drift. It is in this way imperative to discover precisely the impacts of solid splitting on the sidelong stiffness of such structure. This nonlinear breaking investigation strategy with a groundbreaking streamlining procedure and presents a compelling numerical methodology for the stiffness based ideal structure of tall RC structures under help loads. An effective stiffness method is adopted to identify cracked members and to modify their effective cracked stiffness. Iterative strategies were utilized for the workableness examination of tall RC structures to discover their non-straight solidness qualities because of solid breaking. A system model is introduced to show the materialness and productivity of this proposed ideal structure instrument. Conversations about the impacts of solid breaking on the advancement results are likewise included.

considered the effective stiffness of elements that were demonstrated. In this manner, it is helpful to locate a typical or sensible basis to lessen dormancy. Priestley strategy was applied to acquire the compelling unbending nature of components, which are subject to component quality. The outcome of decreasing idleness was a bigger versatile relocation. Then again, dislodging determined by the decreased latency is over-traditionalist.

Luo et.al. [2009] [8] investigated the method of stiffness reduction is adopted to consider non-elastic characteristics of reinforced concrete in a concrete structure standard of the country like the United States and Canada. The concrete structure configuration code of China additionally acknowledged the technique for firmness decrease as a stiffness reduction method to take care of the secondrequest impacts issue when requires. Due to the nonattendance of examination in the firmness decrease of fortified solid extension wharf, the creator had received the numerical reconciliation strategy to modernize reenactment and investigation the guideline of the stiffness change for rectangular segment strengthened bridge pier under various pivotal pressure proportion and various forces of even tremor activity and checked to the test outcome got. Thus, a firmness decrease factor is proposed to think about nonlinear qualities of the fortified reinforced concrete bridge pier.

Elwood et.al. [2006] [5] investigated the stiffness of the structural members of a building strongly affect the calculated response of the structure to ground movement.

For linear analysis of members, member stiffness’s control forecasts of the period of the structure, the loads are distributed within the structure. For nonlinear analysis, we obtain a precise estimate of the associate stiffness that was required to estimate the yield displacement, which in turn, affects the translation ductility anxieties. Real-world, accurate procedures are needed to estimate the effective stiffness up to yielding of each structural component. The FEMA 356 technique significantly misjudges the stiffness of columns with low axial loads, in which there can be important bar slip in the beam-column junctions or footings.

The digest provides real-world recommendations for enlightening estimates of effective stiffness.

Ahmed et.al. [2008] [6] studied the effect of concrete cracking on the lateral response of building structures have been investigated and discussed. The exploration business related to the investigation of the impact of cracking on its stiffness has been studied. The debates in the declarations of the prime boundary identified with the splitting of the concrete cement are additionally talked about. The conditions and adjustment factors suggested in writing and just as in various nation norms to present the non-linearity of cement are likewise given. The surrounded structure plan models are introduced for the quantitative impact of parallel reaction joining the concrete cracking under seismic stacking reliant on Indian seismic code.

Park et.al. [2009] [9] studied the method for identifying arbitrary stiffness reduction in damaged reinforced concrete slab bridges under moving force are proposed and dynamic signs estimated at a few focuses are utilized as response information to mirror the properties of the moving burden's affectability. Specifically, the adjustment in solidness in every component when harm, because of the framework recognizable proof technique, is depicted and examined by utilizing a changed bivariate Gaussian dissemination work.

The technique in this paper is more achievable than the ordinary component-based harm recognition strategy from the computational effectiveness because the system of limited component examination combined with a miniaturized scale hereditary calculation utilizing six obscure boundaries independent of the number of components is considered according to result. The numerical calculations had shown that the technique was a feasible and practical method although there is a modeling error between actual bridge results and numerical model results as well as a measurement error like uncertain noise in the response data.

Pique et.al. [2008] [7] investigated on seismic analysis and design of reinforced concrete structures are performed based on linear response; however, it is universally accepted that under severe earthquakes inelastic response and cracking is accepted. The element properties reflect this condition and the value of beams and columns should be reduced accordingly. In the research, the author had

Zhong et.al. [2010] [10] explored on erosion actuated crack in R.C.C. structures reduced the stiffness of the outer zone concrete. The stiffness reduction is brought about by the conditioning in the split cement. Restricted endeavors were made to show the fine splitting and the comparing impacts on the spread cement. The stiffness degradation factor proposed to model the stiffness degradation of the outer

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concrete. The chance to the breaking of the outer concrete is then decided as the time from the consumption commencement required by the split front to arrive at the external surface of the outer concrete. The proposed firmness debasement factor and the technique to figure the chance to cracking are outlined with two numerical models.

method and equation are then verified with the experimental data obtained from literature studies.

Castel et.al. [2012] [14] researched macro-finite-element (MFE) demonstrating to committed the estimation of the diversion of effectively cracked R.C.C. beams under service force. The consequences of the MFE model were contrasted and explores performed on five R.C.C. beams, including square- and T-section beams and two concretes grades. A successful application of the MFE method to a statically indeterminate beam was also shown.

Li and Xiang [2011] [11] examined R.C.C. walls are the essential horizontal force conveying components in numerous structures intended to oppose tremors. An investigation of the specialized writing shows a significant distinction concerning the compelling stiffness of these structures when exposed to seismic force. In an endeavor to get extra data in regards to the firmness of these structures, a diagnostic methodology, consolidating the flexure and shear parts of twisting, is proposed to assess the viable stiffness of the RC wall tried. Based on this proposed analytical approach, a comprehensive parametric study comprising a hundred and eighty combinations was preformed and a simple equation for assessing effective stiffness of R.C.C. squat structural walls.

Liu et.al. [2012] [15] investigated the flexural stiffness reduction factor of reinforced concrete columns with different shapes and sections considering the properties of material nonlinearity. By the mathematical integral technique, the change of flexural stiffness for existing test models of R.C.C. columns with different shaped sections, size under different axial load, and unlike levels of the seismic deed was analyzed. It was determined that the hypothetical values are in the promising of the test values. As a result, a flexural stiffness reduction value is proposed to reflect features of physical nonlinearity and geometrical nonlinearity of R.C.C. columns with equal L-specially shaped sections and size.

Bonet et.al. [21] concentrated the greater part of the structure codes (ACI-318-2008 and Euro Code–2-2004) proposed the moment magnifier technique to consider the second-order impact to slender strengthened column segments design. Another condition to acquire the successful stiffness EI of slender column sections were proposed. The author's condition is legitimate for any state of the crosssegment, exposed to consolidated pivotal burdens and biaxial twisting, and for both for a brief timeframe and supported force, yet it is just appropriate for the column with equivalent powerful buckling lengths in the two principal bending planes. The new equation extends the proposed EI equation in the ‘‘Biaxial bending moment magnifier method’. The method is capable to apply to practical engineering design applications.

Causevic et.al. [2012] [16] presented results obtained by analysis of two typical structures are presented. The value of shear stiffness, or stiffness to bending of structural beams or walls, was diverse throughout this analysis. Investigated why the EN 1998-1:2004 set the element stiffness reduction to 50% of the initial value, what is the difference in the steel quantity obtained according to linear procedures, how is the relevant load combination were subjective by stiffness reduction, and if the reduction of stiffness is, or is not, taken into account.

Tang et.al. [2014] [17] investigated seismic analysis of concrete structures under maximum earthquakes load required the use of reduced stiffness. Structural walls, different from other flexural components that are sensitive to both flexural stiffness and shear degradations. Accessible trial results demonstrate that it can exaggerate the shear stiffness by more than twice, which would hamper the real forecasts of building periods and shear load disseminations among vertical elements. What's more, the specified consistent malleability limit was received. This paper examined the accessible improved shear and flexural models. Perspectives on the suggested flexural and shear stiffnesses by noticeable plan codes, for example, ACI318-11, Euro code 8, and CSA are incorporated. A database involved dividers exposed to turn around cyclic burdens is framed to assess the exhibition of each model. It was discovered that their current models that could exceed over moderate systematized values with similar effortlessness for employments

Vidovic et.al. [2011] [12] explored the most recent outline in the seismic design of structures as per Eurocode 8 infers considering the impact of cracking while at the same time assessing the stiffness of Concrete element – the stiffness consequences for the size of the seismic forces and lateral displacements. The investigation of the effective stiffness of cracked R.C.C. components was relying upon the measure of longitudinal steel was directed and the size of axial force considering the tension hardening impact. The results obtained through this analysis were then applied to a sevenstory residential building.

Li [2012] [13] investigated the assessment of the early stiffness of columns and walls subjected to seismic loadings has long been a matter of considerable ambiguity. A wideranging study based on the technique is initially carried out the investigated influences of several critical factors. Two simple equations were proposed to estimate the initial stiffness of R.C.C. columns and walls. The accuracy of the

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Castel et.al. [2014] [18] investigated R.C.C. construction in which the deflection regulator is an important performance principle for its serviceability and sustainability. The author had experimented aimed at modeling the effects of both short-term and sustained loading on the instant stiffness of R.C.C. flexural elements. investigational results show that both steel-concrete interface damage (i.e. cover-controlled cracking) attributable to extreme live loading and timesubordinate impacts, for example, creep and shrinkage affects the stiffness of beams. In different models, the finiteelement model that represents the impact of outer cover zone-controlled cracking on the immediate stiffness was proposed. Just the transient reaction to the stack was considered in displayed by the author. By actualizing a harm variable to lessen the bond at the steel-concrete interface as stacking is expanded or during a time of shrinkage and sustained loading. Plus, a model for the inception of cover control cracks dependent on a maximum estimation of the steel stress at the crack area is likewise characterized.

analysis of the structure. Different authors and codes had given different stiffness modifiers for different elements.

Yet there is no clarity of using stiffness modifiers and its effect if it varying through the height of the structure.

Table -1: Stiffness modifiers given by different codes

Codes

Das et.al. [2019] [19] studied that the actual stiffness which depends on strength. Wrong or not proper estimation of member stiffness affects the force distribution and deformation which leads to an inaccurate structural response. Thus, the usage of real effective stiffness established on strength is very significant in nonlinear analyses to gauge the real performance of the building under seismic circumstances. The designed structure has been presented to nonlinear investigations coordinating three classes of stiffness, explicitly, net stiffness, genuine compelling stiffness dependent on strength, and effective stiffness according to FEMA-356. The results picked up from the nonlinear time history investigation showed that the structures broke down with net solidness display exceptionally preservationist float and superior levels in assessment with those of structures with viable stiffness dependent on strength. FEMA determined successful stiffness proportion yielded drift and order level are in the middle of those with gross stiffness and effective stiffness dependent on strength. It was recognized that the estimation of genuine effective stiffness for the column element is a hard procedure. Thus, making it a simple procedure, a product processing strategy called artificial neural system (ANN) has been utilized to assess the effective stiffness of the column. The numerical performances of the ANN model show that it can be used as another tool to estimate the effective stiffness of RC column sections with good accuracy.

Moreover, a model equation is presented based on the factors of a qualified neural network which can be readily used to estimate effective stiffness ratios.

Slab

Beam

Column

Wall

IS 16700-2017

0.35

0.7

0.9

0.9

ACI 318-2019

0.35

0.5

1

0.5

FEMA 356

-

0.5

0.7

0.5

TEC 2007

-

0.4

0.8

-

UBC 1997 Vol 2

0.25

0.34

0.7

0.35

NZS3101.2.2006

-

0.6

1

0.7

3. CONCLUSION It can be concluded that from literature survey that still there is quite scope in finding and application of stiffness modifiers use in analysis of the R.C.C. Structure. we had studied from literature most of codes provide single value of stiffness modifiers for an element. Application of Stiffness modifiers varying through height is yet to discover.

REFERENCES [1]

[2]

[3]

[4]

2.1 Outcome of Literature Survey [5]

It has been observed from the literature survey that most of the author had investigated various methods find initial stiffness for including the crack section effect on the

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Stiffness modifiers

[6]

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Philip C. Perdikaris, Said Hilmy, Richara N. White, “Extensional stiffness, of precracked R/C panels”, Journal of Structural Engineering, Vol. III, No. 3 (1985) pp. 487-504.

Tom Paulay, “Re-definition of the stiffness of reinforced concrete elements and its implications in seismic design”, Structural Engineering International Vol. 1 (2001), pp. 36- 41.

Tom Paulay, “The displacement capacity of reinforced concrete coupled walls”, Engineering Structures Vol. 24 (2002), pp1165–1175.

Chun-Man Chan, Qian Wang, “Nonlinear stiffness design optimization of tall reinforced concrete buildings under service loads”, Journal of Structural Engineering, Vol. 132, No. 6 (2006), pp. 978-990.

K.J. Elwood, M.O. Eberhard, “Effective Stiffness of Reinforced Concrete Columns”, PEER Research Digest Vol. 1 (2006), pp. 1-5.

M. Ahmed, M. K Dad Khan, M. Wamiq, “Effect of concrete cracking on the lateral response of RCC buildings”, Asian

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International Research Journal of Engineering and Technology (IRJET)

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Journal of Civil Engineering (Building and Housing) Vol. 9 No. 1 (2008), pp. 25-34.

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2482-2490.

Taehyo Park, Myung-Hyun Noh, Sang-Youl Lee, George Z. Voyiadjis, “Identification of a distribution of stiffness reduction in reinforced concrete slab bridges subjected to moving loads”, Journal of Bridge Engineering, Vol. 14, No. 5 (2009), pp. 355-365.

Jinquan Zhong, Paolo Gardoni, David Rosowsky, “Stiffness degradation and time to cracking of cover concrete in reinforced concrete structures subject to corrosion”, Journal of Engineering Mechanics Vol. 136, No. 2 (2010), pp. 209-219.

Bing Li, Weizheng Xiang, “Effective stiffness of squat structural walls”, Journal of Structural Engineering, Vol. 137, No. 12 (2011), pp. 1470-1479.

J.L. Bonet, M.L. Romero, P.F. Miguel, “Effective flexural stiffness of slender reinforced concrete columns under axial forces and biaxial bending”, Engineering Structures Vol. 33 (2011), pp. 881–893.

Damir Vidovic, Davor Grandic, Paulo Sculac, “Effective stiffness for structural analysis of buildings in earthquake”, 4th international conference civil engineering - science and practice, (2012), pp. 811-818.

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Arnaud Castel, Thierry Vidal, Raoul Francois, “Finiteelement modeling to calculate the overall stiffness of cracked reinforced concrete beams”, Journal of Structural Engineering, Vol. 138, No. 7 (2012) pp. 889898.Jianfei Liu, Yanjun Zhang, Pengfei Luo, “Flexural stiffness reduction factor of reinforced concrete column with equal I shaped section”, The Twelfth COTA International Conference of Transportation Professionals, (2012), pp.3187-3193.

Mehmed Causevic, Tomislav Frankovic, Nino Mahmutovic, “Effects of stiffness reduction on seismic capacity of buildings”, Gradevinar, Vol.6 (2012), pp.463474.

T.O. Tang and R.K.L. Su, “Shear and flexural stiffnesses of reinforced concrete shear walls subjected to cyclic loading”, The Open Construction and Building Technology Journal, 2014, Vol. 8 (2014), pp. 104-121.

Arnaud Castel, Raymond Ian Gilbert, Gianluca Ranzi, “Instantaneous stiffness of cracked reinforced concrete including steel-concrete interface damage and long-term effects”, Journal of Structural Engineering, Vol.140 (2014), pp. 1-9.

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Sourav Das, Satyabrata Choudhury, “Influence of effective stiffness on the performance of RC frame buildings designed using displacement-based method and evaluation of column effective stiffness using ANN”, Engineering Structures, Vol. 197 (2019), pp. 1-21.

IS 456-2000, “Plain and Reinforced Concrete Code of Practice”, Bureau of Indian Standards, 4th revision, 2000.

IS 1893 part 1-2016, “Criteria for Earthquake Resistant Design of Structure Part 1 General Provisions and Buildings”, Bureau of Indian Standards, 6th revision, 2016.

IS 13920-2016, “Ductile Design and Detailing of Reinforced Concrete Structures Subjected to Seismic Forces-Code of Practice”, Bureau of Indian Standards, 1st revision, 2016.

IS 16700-2017, “Criteria for Structural Safety of Tall Buildings”, Bureau of Indian Standards, 2017.

ACI 318-19, “Building Code Requirements for Structural Concrete”, American Concrete Institute, 2019.

FEMA 356 “Pre-standard and Commentary for the Seismic Rehabilitation of Buildings”, American Society of Civil Engineer, 2000.

TEC 2007, “Turkish Earthquake code”, 2007.

UBC 1997,” Structural Engineering design provision” Uniform Building Code Vol 2,1997.

NZS3101.2.2006, “Concrete structure Standard part-2 commentary on design of concrete structure”, New Zealand Standard, 2006.

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