Study of soil interaction in a model building frame with plinth beam supported by pile group

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1 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 ORIGINAL RESEARCH Open Access Study of soil interction in model uilding frme with plinth em supported y pile group Rvikumr C Reddy nd Gunneswr T D Ro * Astrct This pper presents the results of sttic verticl lod tests crried out on model uilding frme with plinth em supported y pile groups emedded in cohesionless soil (snd). The effect of soil interction on displcements nd rottion t the column se nd lso the shers nd ending moments in the uilding frme were investigted. The experimentl results hve een compred with those otined from the finite element nlysis nd conventionl method of nlysis. Soil nonlinerity in the xil direction is chrcterized y nonliner verticl springs long the length of the pile (τ-z curves) nd t the tip of the pile (Q-z curves) nd in the lterl direction y the p-y curves. The results revel tht the conventionl method gives the sher force in the column y out 2%, the ending moment t the column top out 1%, nd t the column se out 2% to 3%, more thn those from the experimentl results. The response of the frme from the experimentl results is in good greement with tht otined y the nonliner finite element nlysis. Keywords: Nonliner nlysis, Soil structure interction, Experimentl nlysis, Conventionl method, Pile group, Building frme, Cohesionless soil, Plinth em, Model Introduction Soil settlement is function of the flexurl rigidity of the superstructure. The influence cused y the settlement of the supporting ground on the response of frmed structures ws often ignored in structurl design. The structurl stiffness cn hve significnt influence on the distriution of the column lods nd moments trnsmitted to the foundtion of the structure. Previous studies hve, however, indicted tht the effect of interction etween soil nd structure cn e quite significnt. Interction nlyses hve een reported in numerous previous studies such s Meyerhof (1947, 1953), Chmecki (1956), Morris (1966), Lee nd Hrrison (197), Lee nd Brown (1972), nd even few studies in the recent pst such s Deshmukh nd Krmrkr (1991), Noorzei et l. (1994, 1995), Ro et l. (1995), Dsgupt et l. (1998), nd Mndl et l. (1999). The common prctice of otining foundtion lods from the structurl nlysis without llownce for foundtion settlement my, therefore, result in extr cost tht might hve een voided hd the effect of soil structure interction een tken into * Correspondence: tdgtdg@gmil.com Civil Engineering Deprtment, Ntionl Institute of Technology, Wrngl, Andhr Prdesh 564, Indi ccount in determining the settlements. This requires tht the engineers not only understnd the properties of the ground, ut they lso need to know how the uilding responds to deformtion nd wht the consequences of such deformtion will e to the function of the uilding. In this regrd, mny nlyticl works hve een reported on the uilding frmes founded on pile groups y Burgohin et l. (1977), Ingle nd Chore (27), Chore nd Ingle (28, ), Chore et l. (29, 21) nd the experimentl work y Reddy nd Ro (211). But no significnt light ws thrown in the direction of the effect of soil interction on uilding frmes with plinth em founded on pile groups. The im of this pper is to present n experimentl investigtion s well s numericl nlysis through the nonliner finite element nlysis (FEA) of model plne frme with plinth em supported y pile groups emedded in cohesionless soil (snd) under the sttic lods (centrl concentrted lod, uniformly distriuted lod (UDL), nd eccentric concentrted lod). The need for considertion of soil interction in the nlysis of uilding frme with plinth em is emphsized y the experimentl investigtion y compring the ehvior of the frme otined from the experimentl nd numericl 212 Reddy nd Ro.; licensee Springer. This is n Open Access rticle distriuted under the terms of the Cretive Commons Attriution License ( which permits unrestricted use, distriution, nd reproduction in ny medium, provided the originl work is properly cited.

2 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 2 of 15 Tle 1 Comprison of YS group method nd ANSYS on displcement nd forces in the pile group Check point YS group ANSYS method Displcement Lterl t pier top (mm) Axil t pier top (mm) Lterl of 1, 3 pile hed (mm) Axil of 1, 3 pile hed (mm) Rottion ngle of 1, 3 pile hed Forces Lterl t 1, 3 pile hed (kn) Axil t 1, 3 pile hed (kn) 1,8 1,14.6 Moment t 1, 3 pile hed (knm) nlysis with tht y the conventionl method of nlysis. An ttempt is mde to quntify the soil interction effect on the response of the uilding frme in terms of displcements, rottions, shers, nd ending moments through experimentl investigtion. Methods Anlysis progrm using ANSYS The nlysis of the model plne frme with plinth em is crried out using ANSYS for the following cses: 1. Frme with fixed ses to evlute the sher force nd ending moment in the column, which is the usul prctice done known s the conventionl method; 2. Nonliner nlyses to evlute the lterl displcements, verticl displcements nd rottions, sher forces, nd ending moments in the frme; nd 3. Frme with ses relesed y imposing the lterl displcements, verticl displcements, nd rottions mesured from the experiments for the corresponding loding on the frme to get the ck figured sher forces nd ending moments generted in the columns. Vlidtion y comprison with other numericl studies The results of liner nlysis of typicl column supported y pile group using ANSYS were compred with results those y Won et l. (26). A 2 2 pile group structure consisting of pier, pile cp, nd four identicl verticl piles, which re spced y 3 m (i.e., 6D, where D is the pile dimeter), is used for the liner nlysis. The four piles hve n emedded length of 1 m, dimeter of.5 m, nd flexurl rigidity (EI) of 147,264 knm 2. The thickness of the pile cp is.75 m, nd the pile hed condition is fixed. The pier is 1 m in length nd 1 m in dimeter, nd hs flexurl rigidity of 1,963,6 knm 2. The soil condition t the site is modeled s liner springs in the lterl nd xil directions long with the tip springs. The pile group ws sujected only to lterl lod of 1, kn t the pier top. Tle 1 descries tht the results re identicl to those otined from the YS group method s reported y Won et l. (26). Nonliner finite element nlysis (nonliner FEA) The nonliner nlyses were performed for the single y, single storeyed model plne frme with plinth em founded on 2 2 pile groups in sndy soil (Figure 1). The columns, ems, nd piles re modeled using the 3D elstic two-noded em elements. The pile cp is modeled using the four-noded elstic shell elements. The soil round the individul piles ws modeled with nonliner lod trnsfer curves using the COMBIN39 elements. The nonliner constitutive soil models given y Equtions 1, 2, nd 3 re employed for the present prolem. The lterl lod trnsfer curves given y Eqution 1 Figure 1 Modeling of the frme with plinth em long with the pile.

3 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 3 of 15 Tle 2 Scling fctors used in the study Vrile Length Density Stiffness Stress Strin Force Scling fctors 1/1 1 1/1 1/1 1 1/1 3 were used s the API model (Americn Petroleum Institute 1987), kz p ¼ A s P s tnh y ; ð1þ A s P u where A s = djustment coefficient for the sttic p-y curves; P s = governing ultimte soil resistnce; k = initil sugrde rection constnt; Z =depth;ndp u =ultimte soil resistnce. The xil lod trnsfer curves suggested y McVy et l. (1989) re used in this study. Also used re the verticl τ-z springs long the side of the pile s descried elow given y the Eqution 2, Z ¼ r τ G i ln r ð m βþ ðr βþ þ βðr m r Þ ; ð2þ ðr m βþ ðr βþ where β= r τ /τ f ; r = rdius of the pile; τ = sher stress trnsferred to the soil for given Z displcement; r m = rdius out from the pile where sher stress is negligile; G i = initil sher modulus; nd τ f = ultimte sher stress t the point of interest on the pile. As for the nonliner tip spring (Q-Z), the following reltion given y the Eqution 3 is used: Z ¼ Q ð1 νþ ; ð3þ 4r G i 1 Q Q f where Q f = ultimte tip resistnce; G i = initil sher modulus; ν = Poisson s rtio of the soil; r = rdius of the pile; nd Q = moilized tip resistnce for the given displcement Z. The following soil properties re used for snd to represent its resistnce in oth the lterl nd xil directions: ngle of internl friction φ (evluted from the lortory experiments), Poisson s rtio ν ( typicl vlue of.3 is used), ultimte skin friction τ f (evluted from Tomlinson s eqution (Tomlinson 1971)), ultimte tip resistnce Q f, nd sher modulus G i (Kulhwy nd Myne 199). For the nlysis reported herein, the following properties were employed for the loose snd: ngle of internl friction φ of 3, sher modulus G i of MN/m 2, unit weight of soil of 17kN/m 3 nd reltive density of 35%. The frme is loded with centrl concentrted lod, UDL, nd eccentric concentrted lod t nominl eccentricity of 1% of the length of the em (with eccentricity mesured from the center of the em) in increments s pplied in the experimentl progrm; the response in terms of deformtions, rottions, sher forces, nd ending moments is otined for ech lod increment. Experimentl progrm Frme nd pile groups Using the scling lw proposed y Wood et l. (22) nd reproduced in Eqution 1, the mteril nd dimensions of the model were selected: E m I m E p I p ¼ 1 n 5 ; ð4þ where E m is modulus of elsticity of model, E p is modulus of elsticity of prototype, I m is moment of inerti of model, I p is moment of inerti of prototype, nd 1/n is scle fctor for length. An luminum tue with n outer dimeter of 16 mm nd inner dimeter of 12 mm ws Figure 2 Schemtic digrm of the test setup.

4 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 4 of 15 Lterl Displcement t the se of the column (mm) nonliner FEA Centrl Concentrted Lod (N) lterl displcement t the se of the column (mm) nonliner FEA uniformly distriuted lod on frme (N/mm) Figure 3 Vrition of the lterl displcement with the sttic lod. () Lterl displcement t the se of the column (centrl concentrted lod). () Lterl displcement t the se of the column (uniformly distriuted lod). selected s the model pile with length scling fctor of 1/1. This is used to simulte the prototype pile of 35-mm-dimeter solid section mde of reinforced concrete. Columns with height of 3.2 m, em with spn of 5 m, nd plinth em of the plne frme were scled in the sme mnner. Aluminum pltes of 13 mm thickness were used s the pile cps. In the pile group setup, pile spcing of eight dimeter (8D) ws dopted nd the length of the piles ws so selected s to mintin length to dimeter (L/D) rtio of 2 (Chndrsekrn nd Boomindhn 21). The sufficient freestnding length ws mintined from the ottom of the pile cp to the top of the soil ed. Bem column junctions were mde y welding t fixed condition. Screwing of the piles nd columns in the threds which re provided in the pile cp leds to prtil fixity condition. The scling fctors used in the study re presented in Tle 2. Experimentl setup nd instrumenttion The schemtic digrm of the test setup is shown in Figure 2. Tests were conducted on the model pile groups with the frme emedded in snd ed in testing chmer, which ws well instrumented with the dil guges of sensitivity.2 to study the lterl nd verticl displcements nd rottions t the se of the column. Lods on the frme were pplied through the hooks provided t the em in required loctions

5 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 5 of 15 lterl displcement t the se of the column t ner end (mm).25.2 experimentl results.15 nonliner FEA eccentric concentrted lod (N) lterl displcement t the se of the column t fr end (mm) experimentl results nonliner FEA eccentric concentrted lod (N) Figure 4 Vrition of the lterl displcement with sttic lod pplied on frme s eccentric concentrted lod. () Lterl displcement t the se of the column t ner end. () Lterl displcement t the se of the column t fr end. ccording to the type of lods on the em. The model frme ws plced t the center of the testing chmer using the templtes. The snd is then poured in the testing chmer gently through the pores of steel try in lyers to ttin the loose stte nd uniformity for the snd ed. The instlltion procedure simultes the ored pile condition. Test procedure Sttic verticl lods were pplied on the model frme with plinth em y plcing weights on the hngers. The lods were pplied in increments nd were mintined for minimum period to llow the deflection to stilize. During the ppliction of sttic lods, the lterl, verticl displcements t the se of the column

6 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 6 of settlement t the se of the column (mm) experimentl results nonliner FEA Centrl Concentrted Lod (N) 1.4 settlement t the se of the column (mm) experimentl results nonliner FEA Uniformly distriuted lod on frme (N/mm) Figure 5 Vrition of settlement t the se of the column. () Settlement t the se of the column (centrl concentrted lod). () Settlement t the se of the column (UDL). nd the rottion of the pile cp were mesured using the instrumenttion setup s descried erlier. Testing phses Sttic verticl lod tests were conducted on the model frme with plinth em supported on pile groups emedded in the snd ed s shown in Figure 2. Tests were conducted in the following sequence: 1. Centrl concentrted lod is pplied in increments (1, 2, 3 kg, etc.) t the center of the em. 2. The em is loded t the third points with equl lods in increments (3, 6, 9 kg, etc.) to simulte the UDL condition. 3. Eccentric concentrted lod is pplied in increments (1, 2, 3 kg, etc.) t nominl eccentricity of 1% spn of the em.

7 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 7 of 15 settlement t the se of the column t ner end (mm) experimentl results.6 nonliner FEA eccentric concentrted lod on the frme (N) settlement t the se of the column t fr end (mm) experimentl results nonliner FEA eccentric concentrted lod on the frme (N) Figure 6 Vrition of settlement t the ner end nd fr end of the column se. () Settlement t the se of the column t ner end (eccentric concentrted lod). () Settlement t the se of the column t fr end (eccentric concentrted lod). Results nd discussion Lterl displcement, settlement, nd rottion t the se of the column Figure 3, represents the vrition of the lterl displcement with the sttic lod pplied on the frme with plinth em s centrl concentrted lod nd uniformly distriuted lod. From the plots shown herein, it is oserved tht the lterl displcement t the se of the column of frme with plinth em in oth cses is negligily smll. Figure 4, represents the vrition of the lterl displcement with the sttic lod pplied on the frme s eccentric concentrted lod. From the plots shown herein, it is oserved tht the ehvior of the frme with eccentric concentrted lod is different from tht of the frme with centrl concentrted lod nd uniformly distriuted lod. In the cse of the frme with centrl concentrted lod nd uniformly distriuted lod, the se of the column t ner end nd fr end moves outwrd when the lod is pplied on the frme; ut in the cse of the frme with eccentric concentrted lod, the se of column t ner nd fr ends moves in the sme direction with nerly sme mount of displcement (5% difference) nd towrds the eccentricity. The displcement from the experiment shows vrition of 3% to 14% with respect to tht from the nonliner FEA for

8 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 8 of rottion t the se of the column (degrees) experimentl results nonliner FEA centrl concentrted lod on the frme (N).3 rottion t the se of the column (degrees) experimentl results nonliner FEA uniformly distriuted lod on the frme (N/mm) Figure 7 Vrition of rottion t the se of the column. () Rottion t the se of the column (centrl concentrted lod). () Rottion t the se of the column (UDL). eccentric concentrted lod on the frme t ner end, which is 6% to 14% t the fr end. Hence, the displcement from the experiment is in good greement with tht y the nonliner FEA. The vrition of settlement t the se of the column with respect to the centrl concentrted lod nd UDL on the frme is presented in Figure 5,; the vrition of settlement t the ner end nd fr end of the column se for the frme under the eccentric concentrted lod is presented in Figure 6,. The settlement from the experiment shows vrition of not more thn 15% with respect to tht from the nonliner FEA for centrl concentrted lod nd uniformly distriuted lod on the frme. For eccentriclly loded frme t ner end the vrition is not more thn 13%, t fr end it is not more thn 14%. Hence, the displcement from the experiment is in good greement with tht y the nonliner FEA. The vrition of rottion t the se of the column for the centrl concentrted lod nd UDL pplied on the frme is presented in Figure 7,. Menwhile, the vrition of rottion t the column se of the ner nd fr end, respectively, of the frme under the eccentric concentrted lod is presented in Figure 8,. In cse of eccentric concentrted lod on the frme, fter certin

9 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 9 of 15 rottion t the se of the column t ner end (degrees).3.25 experimentl results.2 nonliner FEA eccentric concentrted lod on the frme (N).5 eccentric concentrted lod on the frme (N) rottion t the se of the column t fr end (degrees) experimentl results nonliner FEA Figure 8 Vrition of rottion t the column se of the ner nd fr end. () Rottion t the se of the column t ner end (eccentric concentrted lod). () Rottion t the se of the column t fr end (eccentric concentrted lod). level of loding, rottion t the fr end is chnged from clockwise to nti-clockwise. This is expected ecuse of the lterl movement of the ner nd fr ends re in the sme direction which cuses the fr end to rotte in the reverse mnner. The rottions from the experiment show vrition of 7% to 14% with respect to tht from the nonliner FEA. Hence, the displcement from the experiment is in good greement with tht y the nonliner FEA. In ll the forementioned results, it is oserved tht, for reltively lower lods on the frme, the vlues predicted y the nonliner FEA nd experiment re nerly liner. For higher lods on the frme, the results devite significntly from the linerity. Sher force in the frme y conventionl method, experiments, nd nonliner FEA Sher forces in the frme under the centrl concentrted lod, UDL, nd eccentric concentrted lod hve een plotted in Figure 9,,c. From these plots, it cn e oserved tht the sher force predicted y the conventionl method is lwys on the higher side. For reltively

10 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 1 of sher force in the frme (N) conventionl experimentl results nonliner FEA centrl concentrted lod on frme (N) sher force in the frme (N) conventionl experimentl results nonliner FEA c uniformly distriuted lod on frme (N/mm) 35 conventionl sher force in the frme (N) experimentl results nonliner FEA eccentric concentrted lod on the frme (N) Figure 9 Sher forces in the frme. () Sher force (centrl concentrted lod). () Sher force (UDL). (c) Sher force (eccentric concentrted lod).

11 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 11 of 15 ending moment t the top of the column (N-mm) 8 conventionl 7 experimentl results 6 nonliner FEA centrl concentrted lod on frme (N) 8 ending moment t the top of the column (N-mm) conventionl experimentl results nonliner FEA uniformly distriuted lod on frme (N/mm) Figure 1 Bending moment t the top of the column of the frme. () Bending moment t top of the column (centrl concentrted lod). () Bending moment t top of the column (UDL). lower lods on the frme, the sher force predicted y the nonliner FEA nd experiment follow closely the sher force y the conventionl method. The mximum difference in sher force predicted y the conventionl method nd the nonliner FEA for frme with plinth em is out 2%. The sher force otined from the experiment devites y out 5% of tht given y the nonliner FEA, which indictes tht the nonliner soil model is in good greement with the experimentl results. Bending moment t the top of the column y conventionl method, experiments, nd nonliner FEA Bending moment t the top of the column of the frme under the centrl concentrted lod nd UDL is plotted in Figure 1,; the one of the ner nd fr ends of the frme under the eccentric lod is plotted in Figure 11,. From the ove figures, it is oserved tht the ending moment predicted y the conventionl method is higher thn tht y the nonliner FEA, indicting tht the conventionl method of nlysis for otining the design moment is uneconomicl. Compred with the ending moment predicted y the nonliner FEA, the reduction in ending moment of the frme with plinth em is out 1% of the ending moment from the conventionl method. The point to e noted with respect to the ending moments t the top of the column of the frme predicted y different methods is tht though the

12 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 12 of 15 ending moment t the top of the column t ner end (N-mm) 8 7 conventionl 6 experimentl results nonliner FEA eccentric concentrted lod on the frme (N) ending moment t the top of the column t fr end (N-mm) conventionl experimentl results nonliner FEA eccentric concentrted lod on the frme (N) Figure 11 Bending moment of the ner end nd fr end of the frme under the eccentric lod. () Bending moment t top of the column t ner end (eccentric concentrted lod). () Bending moment t top of the column t fr end (eccentric concentrted lod). percentges of vrition my not e gret, the differences re significnt ecuse the mgnitudes of ending moment re of multiples of thousnds. This indictes the need for considertion of soil interction in evluting the design prmeters in uilding frme. The vlues of ending moment predicted y the nonliner FEA nd experiments differ y 2% to 3% only, which indictes tht the nonliner soil model is well suited for representing the nonliner ehvior of the soil. Bending moment t the se of the column y the conventionl method, experiments, nd nonliner FEA The vrition of ending moments t the se of the column of the frme under the centrl concentrted lod nd UDL hve een plotted in Figure 12,. Figure 13, shows the vrition of ending moment t the se of the column of the ner end nd fr end, respectively, of the frme under the eccentric concentrted lod. These figures show tht the conventionl method gives ending moment 2% to 3% higher vlue thn tht of the

13 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 13 of 15 Bending moment t the se of the column (N-mm) 4 35 conventionl 3 experimentl results 25 nonliner FEA Centrl concentrted lod on the frme(n) 4 Bending moment t the se of the column (N-mm) conventionl experimentl results nonliner FEA Uniformly Distriuted Lod on the frme (N/mm) Figure 12 Vrition of ending moments t the se of the column of the frme. () Bending moment t the se of the column (centrl concentrted lod). () Bending moment t the se of the column (UDL). ending moment from nonliner FEA. Hence, from the ove results, it is to e noted tht the considertion of soil interction reduced the ending moment considerly when compred to the frme nlysis with fixed ses. The ending moments given y the experiments gree well with those y the nonliner FEA with vrition of 5% to 7%, indicting tht the soil nonlinerity is well represented y the constitutive reltions used for the soil. Conclusions Bsed on the results of the present experimentl nd numericl investigtions on the model uilding frme with plinth em resting on pile groups emedded in cohesionless soil, the following conclusions re drwn: As the lod on the frme increses, the ehvior of the frme in terms of displcement nd rottion t the se of the column predicted y nonliner FEA nd experiment ppers to e liner for reltively smller lods, nd for higher lod rnge they show nonliner vrition. For eccentric concentrted lod on the frme fter certin level of loding, rottion t the fr end is chnging its sign s the lterl displcements t ner end nd fr end re in the sme direction. The displcements nd rottions from the experimentl

14 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 14 of 15 Bending moment t the se of the column t the ner end (N-mm) 35 conventionl 3 experimentl results 25 nonliner FEA Eccentric concentrted lod on the frme (N) Bending moment t the se of the column t the fr end (N-mm) conventionl experimentl results nonliner FEA Eccentric concentrted lod on the frme (N) Figure 13 Vrition of ending moments t the se of the column of the ner end nd fr end of the frme. () Bending moment t the se of the column of ner end (eccentric concentrted lod). () Bending moment t the se of the column of fr end (eccentric concentrted lod). results nd the nonliner FEA show mximum difference of out 15%, indicting tht the nonliner curves used to chrcterize the soil ehvior re generlly good for representing the lod displcement response of the soil. The conventionl method of nlysis gives sher force of out 2% higher thn tht y the nonliner FEA. As the lod cting on the frme increses, the percentge of vrition of sher force predicted y the conventionl method with respect to tht of the nonliner FEA lso increses. The conventionl method gives ending moment t the top of the column tht is out 1% higher thn tht y the nonliner FEA for the frme with plinth em, ut such difference is still significnt s the ending moment vlues re in the multiples of thousnds. The conventionl method gives ending moment t the se of the column tht is 2% to 3% higher thn tht y the nonliner FEA for the frme with plinth em. For nominl eccentricity given for the concentrted lod (1% length of the em), the conventionl method nd nonliner FEA for the frme

15 Reddy nd Ro Interntionl Journl of Advnced Structurl Engineering 212, 4:11 Pge 15 of 15 with plinth em gives higher vlue of ending moment t the column se of the fr end from the lod thn the one of the ner end. The reson ehind this ehvior is tht the displcements nd rottions t fr end re lower thn the ner end. The response of the frme in terms of the design prmeters (i.e., sher nd ending moment) from the conventionl method of nlysis is lwys on the higher side irrespective of the level of loding. The sher force nd ending moments from nonliner FEA of the frme with plinth em were reduced considerly when compred to the conventionl method of nlysis which revels the need for considertion of the interction etween the uilding frme with plinth em, pile foundtion, nd soil. Competing interest The uthors declre tht they hve no competing interests. Authors contriutions RR crried out the experimentl nd nlyticl study under the guidnce of GTDR. GTDR lso prticipted in the sequence lignment nd drfted the mnuscript. Both uthors red nd pproved the finl mnuscript. Acknowledgement The uthors thnk the director of NIT, Wrngl nd the hed of the deprtment of Civil Engineering, NIT, Wrngl for their kind support during the experimentl investigtion. Mndl A, Moitr D, Dutt SC (1999) Soil-structure interction on uilding frme: smll scle model study. Int J Struct, Roorkee 18(2):92 17 McVy MC, Townsend FC, Bloomquist DG, O Brien M, Cliendo JA (1989) Numericl nlysis of verticlly loded pile groups. In: Proceedings of the 1989 foundtion engineering conference, Evnston, Illinois, June 1989, vol. 1. ASCE, New York, pp Meyerhof G (1947) The settlement nlysis of uilding frmes. Struct Eng 25: Meyerhof G (1953) Some recent foundtion reserch nd its ppliction to design. Struct Eng 31(6): Morris D (1966) Interction of continuous frmes nd soil medi. 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