Evaluation of Base Ground Stiffness on Statically Indeterminate Framed Building Structures

Transcription

1 6 JSAC 1/14 valuation of Bae Ground Stiffne on Statically Indeterminate Framed Building Structure Received 16/3/4 Accepted after reviion 16/5/31 valuation of Bae Ground Stiffne on Statically Indeterminate Framed Building Structure Ignacio Villalon*, Deivida Martinavičiu, Mindauga Griciu, Šarūna Kelpša Department of Building Structure, Faculty of Civil ngineering and Architecture Kauna Univerity of Technology, Studentu t. 48, LT Kauna, Lithuania Mindauga Kaiulevičiu JSC Smailui liauta, Piliaalnio t. 3, LT-464 Kauna, Lithuania *Correponding author: The aim of thi paper i to invetigate the influence of the modulu of ubgrade reaction in tatically indeterminate framed tructure. In building deign the interaction between ground and foundation can be modelled variouly: uing pring intead of upport, modelling the wholeale oil a finite element, etc. The mot common ituation in practice i that the interaction i modelled uing the pring. Neverthele, there i not jut one approved method to calculate it, and engineer ue different method, propoed by variou author. In practice the ettlement of foundation are uually calculated and compared with the limit value. However, in ome cae the impact of ettlement i not taen into account on the analyi of the tructure. During the deign proce, the number of borehole i alway limited. Therefore, the real ituation cannot be conidered exactly. A a reult, unforeeen ettlement may caue the coniderable reditribution of internal force, leading to the cracing or even to the failure of the tructure. In thi reearch, different calculation method of modulu of ubgrade reaction are preented. Mot of thee method are adopted for the bae of foundation conited of one oil layer. Therefore, an evaluation propoal of the modulu of ubgrade reaction for multi-layered oil, uing the reviewed method, i uggeted. Uing thoe method, the modulu of ubgrade reaction of oil of 4 pecific borehole were calculated and compared. Furthermore, internal force of two-toried framed building were calculated and compared in two different cae. In the firt cae the calculation are performed conidering the ettlement of the foundation. The ettlement are calculated uing particular geological ituation. In the econd cae all upport are aumed to be rigid. KYWORDS: bae ground, modulu ubgrade reaction, ettlement, reditribution of internal force. Introduction Journal of Sutainable Architecture and Civil ngineering Vol. 1/ No. 14 / 16 pp. 6-7 DOI /j1.ace Kauna Univerity of Technology The ettlement of the foundation are a very ignificant factor, which affect the behaviour of tructure of the deigned building. If the ettlement in the deign proce are not evaluated accurately, it may caue undeirable effect for the element of the building: crac and coniderable deformation may occur in the contruction. The whole tructure may even collape. Therefore, evaluation of thoe ettlement i a ubtantial tage in the deign proce. Different tandard and recommendation, which limit the ettlement of foundation exit. It i determined in appendix H of N :4: urocode 7 (further C7) that for tructure with individual foundation, the ettlement up to 5 mm are acceptable. C7 and other author (eg. Sempton and McDonald (1956), Polhin and Toar (1957), Bjerrum (1963) and other) alo limit the ratio of

2 61 ettlement of adjacent foundation, becaue when the foundation ettle irregularly, additional dangerou internal force in the tructure may be caued. On purpoe to predict and avoid the negative effect of ettlement of foundation, in the deign proce it i very important to decribe and evaluate the interaction of oil particularly accurately. The mechanical behaviour of oil i very complex becaue of it nonlinear, heterogeneou and tre dependent nature. Therefore, in the modelling of oil, frequently particular aumption are admitted, implifying the complex mechanical behaviour of oil. One of the mot important aumption i Winler (1867) uggeted model. Winler (1867) local elatic deformation theory decribe the oil a a pring, which ha a particular tiffne. That tiffne i named the modulu of ubgrade reaction and i one of the mot ignificant magnitude in the calculation of the ettlement of foundation. It i a conceptual magnitude, which decribe the ratio between applied load and the ubequent deformation of oil (Bowle 1997). The main iue of Winler model i the calculation of the modulu of ubgrade reaction. One of the firt experiment which wa made on purpoe to obtain thi magnitude wa performed by Terzaghi (1955), by loading the ubgrade with a metal plate. However, thee experimental reult are not ufficiently accurate becaue of the fact that modulu of ubgrade reaction depend not only on propertie of oil, but alo on the magnitude of load and geometrical parameter of the foundation, wherea thee condition are hardly achievable while performing the experiment with metal plate. A Ziaie-Moayed and Janbaz (9) oberved, the method of Terzaghi become inaccurate when dimenion of foundation are much greater than dimenion of the plate. The modulu of ubgrade reaction depend on variou factor: the width of foundation bae (B), hape, the thicne of bae, depth (D), the elatic modulu of material of foundation bae ( f ) and the moment of inertia (I f ), Poion ratio of oil (ν), the load which pre the oil, the oil deformation modulu ( ) and etc. The hear deformation (Poion ) coefficient of oil decribe the ratio between hear and normal tree. The tentative magnitude of thi coefficient may be choen by Rowe (1) repreented propoal: for clay in undrained condition,5; for clay in drained condition,-,3; for thic and,3-,4; for powdery and,1-,3. The modulu of ubgrade reaction i a ueful magnitude in modelling of foundation and ubgrade interaction. A mentioned above, it doe not depend on internal factor a the natural propertie of oil, but alo on external factor uch a the geometrical characteritic of foundation or the magnitude of loading. For thi reaon, the modulu of ubgrade reaction i not a fundamental property of oil. Depending on the mentioned external factor, for the ame oil, the coefficient may obtain different magnitude. There doe not exit a united calculation method of the modulu of ubgrade reaction. Therefore, the comparable analyi of different calculation method wa performed. Further, ten different method of calculation of coefficient are analyed and evaluated according to it accuracy. Moreover, an influence of different ettlement of foundation for tructure i aeed. A comparable analyi of reditribution of the internal force of the modelled contructional element of the tructure i performed by a computer-baed program. The analyi conit of comparing the reditribution of internal force when the ettlement of all foundation are the ame and the cae where the ettlement are different. The firt analyed method i the Winler model. Thi model decribe the oil a an elatic ytem in which there i a linear dependence between the applied load and the ubequent ettlement of the foundation. The mathematical value which decribe thi dependence, i the modulu ubgrade reaction : Calculation method F = (1) where: F applied load to the oil; foundation ettlement.

3 6 In order to determine the modulu ubgrade reaction, the value of the ettlement of the foundation (method No. 1) mut be previouly obtained. There are different way to calculate thee ettlement. In thi cae, the method of addition wa ued, where the total ettlement of the oil conit of the deformation of each mall layer in which the oil i divided. Uing the principle of the elatic theory F. Schleicher (196) preented a mathematical expreion to calculate the modulu ubgrade reaction (method No. ): ω B 1-ν () where: ω form coefficient of the foundation (for quared elatic foundation lab ω=,95; for quared rigid foundation lab ω=,88); deformation modulu of oil. Veic (1961) conidered the influence of the material and the ection of the foundation and propoed an expreion to obtain (method No. 3): ' B (3) The value can be obtained uing the next equation ', B I f f 1 (4) where: f elatic modulu of foundation; I f moment of inertia of the ection of the foundation. For practical purpoe Veic reduce the expreion 1, to (method No. 4): B 1 v (5) According to Timoheno and Goodyear (1951) method to calculate foundation ettlement, J. Bowle (1997) propoed another equation to obtain (method No. 5): Δq ΔH B 1 ν m I S I F (6) where: I F influence factor, which depend on the ratio D/L and L/B (L foundation length; B foundation width; D foundation lab depth) and on Poion ratio ν; I S influence factor, which depend on L /B ratio (L and B effective foundation dimenion), width of the oil layer, Poion coefficient ν and depth of the foundation D. m number of corner contributing to ettlement (at a corner of the footing m=1; at the centre m=4).

4 63 In all of the preented method modulu ubgrade reaction i obtained from oil deformation modulu. However, thi property ometime i not nown. Therefore, it can be ueful to count on other ind of approximation not depending on. J. Bowle (1997) propoed a method in which modulu ubgrade reaction can be obtained from the allowable bear capacity of the oil q a (method No. 6): 4 SF q a (7) where: SF afe factor; q a allowable bear capacity. Selvadurai (1984) propoed another method to obtain (method No. 7):, 65 B 1 ν (8) Modulu can be obtained uing finite-element analyi oftware Autode Robot Structural Analyi Profeional (further Autode Robot) (method No. 8). Thi program obtain by predicting the ettlement of a footing by the method of addition (which i ued in the method No. 1). Another way to determine modulu of ubgrade reaction i to apply the finite layer method. It i aumed that, under a footing, there are vertical hear force between the particle of the oil, o that the oil behave platically. However, going deeper in the ground, it occur that thee hear force become weaer and, at ome depth, diappear. Then, the conidered oil behave elatically. Thi mean that there i a layer under the footing of thicne H l in which there are platic deformation. It i recommended to tae H l =1/4 B. The reult obtained by ome author (Gorbunov-Poadov et al. (1984), Zhemochin B. N. and Sinityn A. P. (1947)) are provided in (8) and (9) equation: 1 ν H l (9) 1 ν 1 ν 1 ν H l (1) The firt equation (q. 9) conider that the platic layer can lide on the ground, which i under it (method No. 9); the other equation aume that lip doe not occur (method No. 1). In mot of analyed method, modulu depend on other ground propertie lie deformation modulu, Poion coefficient ν and bear capacity q a. When under the footing i a one-layered oil, thee propertie are aumed be uniform and the modulu can be obtained imply uing the conidered method. Neverthele, frequently ground conit of everal layer with different type of oil, mechanical propertie, granulometric compoition, thicne, water aturation degree and etc. Therefore, in order to calculate modulu ubgrade reaction uing the analyed method and conidering thee different propertie between oil layer, author propoe to apply the influence factor i to each oil layer. Thi coefficient depend on the thicne and the depth of the conidered layer. The Calculation of modulu ubgrade reaction for a multi-layer oil

5 64 thinner and deeper layer i the le ignificant layer. The influence factor i alo depend on the deformation modulu of the layer and on the form and dimenion of the foundation. Firt of all tranitional coefficient tr,i i obtained: tr,i hi,i L1 B1 D z i L1 B1 zi L1 B1 arcin D zi L1 B1 L1 zi B1 zi (11) where: L 1 half of the length of the foundation; B 1 half of the foundation width; z i upper depth of the conidered layer. D L 1 B1 z1 (1) The tranitional coefficient may be obtained from the table preented by ome author (e. g., Šližytė et al. (1)). In thi cae tr,i can be elected from the ratio between foundation η L/B and from the relative depth of the analyed layer ζ z/b. Tranitional coefficient tr,i are normalized and the influence factor of layer i obtained: i tr,i n tr,i i1 (13) The final joint propertie of the overall multi-layered oil are calculated by thee equation: n i1 i,i (14) n i1 i i (15) q a n i1 i q a,i (16) = 1, 5 B. For wea oil it can be adopt- Applying thi method, the ignificant ground depth i ed H = B. H

6 65 In order to chec the accuracy of the preented method, the modulu ubgrade reaction wa obtained from four different geologie borehole. Two of them (geologie A and B) are one layered oil and the other two (geologie C and D) are multi-layered oil. For each one of them, the modulu of ubgrade reaction i calculated, applying three different vertical load to a quare hallow footing. The load are: 5 N, 1 N and N. The dimenion of the quare hallow foundation are elected in each cae according to oil parameter and the magnitude of load, in the way that bearing capacity would not be exceeded (dimenion of foundation vary from 1,3 m to 3,6 m). The propertie of each geological layer are preented in table 1. Layer No. Soil H l, m q c, MPa, MPa c, Pa φ, γ, N/m 3 ν Soil A 1 Sand, 5, 15, 1 3,6 1,85,5 Analyi of the different method Table 1 Propertie of the layer of the oil Soil B 1 Clay,, 18, 35,7 19,,16,35 Soil C 1 Silty clay,45 1, ,4,3 Clay,7, ,4,3 3 Sandy ilt 3,4 4, ,9,3 4 Silty and,5 14, ,1,5 5 Sandy ilt,5 7, ,9,3 6 Silty and 1,3 1, ,1,5 Soil D 1 Sand, 5, ,,5 Sand,6 4, ,,5 3 Sand with ome gravel,1 6, ,,5 4 Gravel 1,3 6, 78 1, 44,9,5 5 Sandy ilty clay 1,1 8, 8 35, 6,8,35 6 Sandy gravel,6 11, 33 1, 41 1,,5 7 Sandy ilty clay 4,8 14, 14 35, 6,8,35 where: H l layer thicne; q c cone tip reitance; deformation modulu; c effective coheion; φ oil friction angle; γ weight; ν Poion coefficient. The calculation of modulu wa carried out for all 4 geological ituation. The reult were obtained uing the 1 different analyed method, which are hown in Fig. 1 and. Winler method (method No. 1) i aumed to be the tandard with which the other method can be compared. The reult obtained by method No. 9 and 1 differed coniderably: value were about 4 time

7 66 bigger than thoe obtained uing the other method. A a conequence, method No. 9 and 1 were not analyed. Fig. 1 Value for oil A (left) and oil B (right) , 1 4 N/m , 1 4 N/m Method No. Method No. 5 N 1 N N 5 N 1 N N In Fig. 1 value of one-layered oil A (andy oil) and B (clayey oil) are hown, calculated uing all the dicued method. In both cae the calculation how common accuracy trend. The obtained reult are quite imilar, however uing the reduction of Veic equation (method No. 3) and Salvadurai expreion (method No. 7), value are the lowet. It mean that by thee method, coefficient i calculated too carefully. In the cae of the econd method of Bowle (method No. 6) the difference of the obtained value, applying different magnitude load, i the highet. Fig. Value for oil C (left) and oil D (right) , 1 4 N/m Method No., 1 4 N/m Method No. 5 N 1 N N 5 N 1 N N In Fig. it i preented the ubgrade modulu value (uing 8 different method) for oil C and D. Soil C and D are compoed of everal different layer. Therefore, influence factor i i included in the calculation of modulu. In one-layered oil diagram (Fig. 1) it can be een the reembling trend: uing method No. 3 and 7, the reult eep a reerve (are not coniderable); the reult of method No. 6 are trongly dependent of the magnitude of the applied load. Uing the method No. 1, footing ettlement were predicted by the addition method, and then the modulu of ubgrade reaction wa calculated (eq. 1). Modulu i obtained directly from

8 67 the definition of Winler theory. On the other hand, the other method are approximation from which the modulu i calculated uing the other oil and footing propertie. Therefore, method No. 1 i aumed to be the tandard with which the other method can be compared in order to determine it accuracy. The difference between each method and Winler (method No. 1) i calculated from the next equation:,i,1,1 1% (17) Difference Δ wa calculated for each one of the oil and for each one of loading cae (5 N, 1 N and N), applying the different calculation method. The unified Δ value for each oil i obtained calculating average of the obtained value in each loading cae. Finally average Δ value for one-layered oil (A and B) and average Δ value for multi-layered oil (C and D) were obtained. The comparion analyi of thee final Δ reult i preented in Fig. 5. Δ, % Method No. Δ, % Method No. Fig. 3 Method comparion with No.1 (Winler ) method for one-layered A and B geologie (left diagram) and for multi-layered C and D geologie (right diagram) In Fig. 3 it can be noticed that the cloet reult to Method 1 are obtained with method No. 8 (Autode Robot) and No. 5 (J. Bowle). In the cae of one-layered (A and B) oil thee method are very precie. Difference Δ reach 6 % and 8 %, repectively. In the cae of multi-layered (C and D) oil, Δ i more coniderable: for both i about 1 %. A far a thee two mentioned method (No. 8 and No. 5) are the mot exact path to obtain, it i recommended to apply them in the deign of building foundation. Alo in Fig. 3 it can be een that when the layer influence factor i in the calculation of multi-layered oil i introduced, accuracy (Δ) value change (in comparion with the cae of one-layered oil). For ome method (No. 5 and 8) the difference Δ grow about 5-8 %. In other cae (method No. 3, 4, 6 and 7), the difference Δ decreae up to 1 % (in thi cae, the introduction of influence factor i increae the accuracy of the reult). In method No., Δ remain imilar: it jut increae for multi-layered oil up to %. Broadly peaing, uing any calculation method, the value of Δ between one-layered and multi-layered oil do not differ more than 1 %. Therefore, the ue of layer influence factor i i jutified. Structural analyi wa carried out, uing program Autode Robot. The goal wa to explore the change of internal force in the tructure, uing modulu of ubgrade reaction obtained by different method. There were three method ued in the analyi: Bowle equation (uing influence factor for multi-layered oil) (method No. 5), calculation with Autode Robot (method Contructional analyi

9 68 No. 8) and Winler method (method No. 1). After the analyi, it wa noticed that the value of the internal force obtained from the different three method were very imilar: the difference were up to 1%. A a reult, further in thi wor, only the internal force obtained uing the modulu of ubgrade reaction calculated by method No. 5 will be hown. Calculation cheme i repreented in Fig. 4. The modelled tructure i a two-toried building. The height of the firt torey i 3 m. The ditance between the floor of the firt torey and the bottom chord of the tru i 3 m. The firt floor ha five 6 meter long pan. The pan of the econd floor i 3 m. In the calculation, the tranvere frame i being analyed. It tep in the longitudinal direction of the building i 6 meter. Fig. 4 Calculation cheme The reditribution of internal force wa explored in the tranvere frame of the tructure. Three different geological ituation were aumed in order to carry out the analyi: a) Situation No. 1: abolutely rigid oil under all the upport of the building. b) Situation No. : relatively wea oil (oil ) under all the upport of the building. c) Situation No. 3: relatively trong oil (oil F) under upport S1 and S; relatively wea oil (oil ) under upport S3, S4, S5 and S6. Now the oil wa choen to be different from the oil ued in the previou chapter. The oil in thi chapter wa choen with the purpoe to give potentially extreme difference of internal force. The elatic behaviour of the oil i modelled introducing pring in the ituation No. and No. 3. The elatic modulu of thoe pring i the modulu of ubgrade reaction of the conidered oil and F. The propertie of oil and F are hown in Table. Thoe characteritic have been obtained by evaluating geological borehole from the ame contruction ite. In pite of their proximity, their characteritic are coniderably different. The bending moment diagram under the three different decribed ituation are hown in Fig. 5. Note: boxe of internal force of column have olid line. Boxe of internal force of beam have dahed line. Value of bending moment in Fig. 5 are divided by 57,67 in beam and by 161,7 in column (maximum value). In Fig. 5, it can be noticed that, when the pring are introduced (ituation No. ) intead of rigid upport (ituation 1), bending moment in the beam increae up to 43 %. The maximum increae of bending moment can be noticed in beam B1 and B5, in the place, where thoe beam are connected to column C1 and C6 repectively. However, the value of bending moment in everal beam decreae. The bigget decline of bending moment i noticed in the place, where beam are connected to column C and C5. In thee place the value of bending moment de-

10 69 Layer No. Soil H l, m q c, MPa, MPa c, Pa φ, γ, N/m 3 ν Soil Table Characteritic of layer of oil and F 1 Sand,1 3, 9-3 1,,5 Coare and 1, 6, ,, 3 Coare and 1,1 3, ,5, 4 Coare and,8 11, 33 1, 37 1,, 5 Sandy ilty clay 1, 6, 6 7, 6 3,,3 Soil F 3 Sand with ome gravel 1, ,5,5 4 Sand with ome gravel 1, ,,5 5 Coare and, ,5, 6 Coare and, ,, 7 Sandy ilty clay 1, ,,3 where: H l layer thicne; q c cone tip reitance; deformation modulu; c effective coheion; φ oil friction angle; γ weight; ν Poion coefficient. Fig. 5 Diagram of bending moment creaed by up to 1 %. There are alo ignificant difference of bending moment in the column. Bending moment increaed by up to 41 % at the top of the column C1 and C6. Cae Maring Note 1. Situation No. 1. Situation No. Introducing different type of oil (ituation 3. Situation No. 3 No. 3) and comparing it to the reult obtained from ituation No., where there i only one type of oil, change are alo noticeable. The maximum increae of bending moment, 7 %, can be noticed in beam B1, in the place where thi beam i connected to column C. Comparing the latter ituation, there i a coniderable decreae of bending moment in ome tructure. For example, the bending moment in the midpan of beam B1 wa up to 1 %. Although the change of bending moment in column are not o ignificant, they hould alo be evaluated. The mot noticeable decreae, 3 % occurred at the top of column C1. The increae of bending moment in column i not coniderable. Table 3 Legend of the diagram

11 7 Diagram of axial force under three type of oil rigidity ituation are repreented in Fig. 6 Thoe ituation are repreented in Table 3. Note: Value of axial force in Fig. 6 are divided by the value of maximum axial force - 78,76. Fig. 6 Diagram of axial force Maximum and minimum axial force in column were obtained. However, under all of thoe ituation tenion did not occur and the difference of axial force are very low. A a conequence, maximum axial force are more relevant and only the change of maximum axial force will be dicued. In the column C1 there are no large difference of axial force under the three ituation of oil rigidity. In thi column there i no difference between the reult obtained from ituation No. and No. 1. There are ignificant change under the ituation No. 3, when axial force decreae by 5 %. In the column C the change of axial force under ituation No. decreae 6 % in comparion to ituation No. 1. Under the ituation No. 3, axial force increae by up to 1 %. Axial force in column C3 under ituation No. 1 and No. are imilar. However, in the ituation No. 3 the axial force of thi column decreae by 15 %. There are no coniderable change of the axial force in column C4 and C6. Axial force in column C5 only diverge under the ituation No. 1. Under the elatic ituation (No. and 3) the value of axial force decreaed by 6 % in comparion to ituation No. 1. Diagram of lateral force under three type of oil rigidity cae are repreented in Fig. 7. Thoe cae are repreented in Table 3. Note: Value of lateral force in Fig. 7 are divided by 38,63 in beam and by 73,5 in column (maximum value). Fig. 7 Diagram of hear force

12 71 When the pring are introduced (ituation No. ) intead of rigid upport (ituation No. 1), the lateral force in the beam increae by up to 7 %. Thi maximum increae i noticed in beam B1 and B5, in the connection to column C1 and C6. The decreae of lateral force in ome of the beam i alo coniderable. Maximum decreae i noticed in beam B, in the connection to column C. Thi maximum decreae reache 6 %. When comparing ituation No. to ituation No. 1, it can be een, that lateral force increae in all of the column of the firt floor (column C1 to C6). The maximum increae, up to 38 %, occur in column C1 and C6. Comparing the value of the lateral force obtained from ituation No. 3 to the reult obtained from ituation No. 3, ignificant change can be noticed. The maximum increae of lateral force occur in beam B, in it connection to column C. The value obtained in ituation No. 3 are 1 % larger than in ituation No.. The maximum decreae i alo in beam B. Thi decreae i noted at the place where the beam B i connected to the column C3. The value obtained in ituation No. 3 decreae 18 % in comparion to ituation No.. While comparing the change of lateral force in column under ituation No. 3 to ituation No., the maximum increae, up to 8 %, can be noticed in column C4 and C5. The maximum decreae alo occur in the ame column. It i poible becaue there are many load combination. Thi lead to the fact that there are diagram on both ide of the column. Lateral force increae on one ide and decreae on the other ide. 1 The comparable analyi of calculation method of the modulu of ubgrade reaction wa performed. When analying it wa aumed that the mot realitic reult are obtained with the firt method (Winler ). The accuracy of other method wa determined by comparing thoe method with the method No. 1 in calculating the difference Δ. The cloet reult to firt method were derived from calculation method No. 5 (Bowle) and No. 8 (Autode Robot) where the difference Δ doe not exceed 1 %. Applying method No., 4 and 6 the value difference Δ ocillate vary from 1 % to 5 %. The larget difference from the firt method i obtained calculating by method No. 3 (implified Veic equation) and No. 7 (Selvadurai) when the difference Δ reache 48 %. Mot of the conidered method are dedicated to homogenou oil. However, in practie often occur that the oil i conited of many layer, which have different propertie. In order to calculate the modulu of ubgrade reaction of uch oil, it i propoed to ue the layer influence factor i. By ome method (method No. 5 and 8) the difference of method increaed in one-layer cae by 5 %. The difference Δ of other method remained imilar or even le than Δ of thee method in one-layer cae. The difference Δ, while calculating the coefficient by the ame method for one-layered and multi-layered oil, never differed more than 1 %. Therefore, the application of the coefficient i i adviable and rational in the determination of the modulu of ubgrade reaction of a multi-layered oil. 3 When the analyi of conidered building wa performed, it wa determined that evaluation of the modulu of ubgrade reaction ha coniderable influence for the internal force of the tructure. Reditribution of internal force occurred with particular intenity when there were modelled different bae ground tiffne (ituation No. 3) under upport S1 and S. Reditribution of bending moment wa the mot relevant: under ituation No. 3 it increaed more than 7 %. Moreover, there wa a coniderable variation of hear force in the column. valuating the bae ground tiffne (ituation No. ) and comparing it with the internal force of the cae where the upport are rigid (ituation No. 1), the increae reached even 4 %. In beam coniderable change of hear force were determined introducing the different type of oil (ituation No. 3). It exceeded %. The change of axial force were not uch coniderable (up to 1 %). However, the evaluation of thoe change i eential. 4 The analyi of tructure wa performed evaluating the different modulu of ubgrade reaction in everal cae: Bowle method (No. 5), Winler method (No. 1) and Autode Robot method (No. 8). Obtained internal force were compared in all cae. Calculating the tiff- Concluion

13 7 ne with method No. 5 (uing the influence factor for multi-layered oil i ) and comparing it with the other choen method, inconiderable difference were obtained (up to 1 %). A a conequence, it i obviou that reult obtained from method No. 5 are accurate, and that influence factor i i reliable and appropriate to ue in the analyi of multi-layered oil. Reference N (7) (nglih): urocode 7: Geotechnical deign - Part : Ground invetigation and teting. Bowle, J.. Foundation Analyi and Deign. 5th ed. New Yor: Mc Graw-Hill; Bjerrum L. Contribution to the dicuion. Sect. 6, 6th.C.S.M.F.., 1963; Wiebaden; vol. : Gorbunov-Poadov M.I., Maliova T. A., Solomin V. I. Calculation of tructure of elatic bed. Mocow: Stroyizdat; Polhin D.., Toar R. A. Maximum allowable non-uniform ettlement of tructure. 4th I.C.S.M.F.., 1957; London; Vol. 1: Rowe, R. K. Geotechnical and Geoenvironmental ngineering Handboo. 1 t ed., New Yor, Springer cience + Buine Media, 1. Sadrearimi, J. Comparative tudy of method of determination of coefficient of ubgrade reaction. lectronic Journal of Geotechnical ngineering, 9, Vol. 14, Bund.. Schleicher, F. Zur theorie de baugrunde [The theory of oil]. Bauingenieur, 196; 7: , Selvadurai, A.P.S. The flexure of an infinite trip of finite width embedded in an iotropic elatic medium of finite extent. Int. J. Numer. Anal. Meth. Geomech., 1984; 8: Sempton A. W., McDonald D. H. Allowable ettlement of building. Proc. I.C., 1956; London; Vol 5: Šližytė, D., Medzvieca, J., Macevičiu, R. Pamatai ir pagrindai [Foundation and ground]. Vilniu: Technia; 1. Veic, A. B.Beam on latic Subgrade and the Winler Hypothei. Proceeding of 5th International Conference of Soil Mechanic, 1961; Pari: Terzaghi, K. V. valuation of Coefficient of Subgrade Reaction, Geotechnique,1955; 5(4): Ziaie-Moayed, R., Janbaz, M. ffective Parameter on Modulu of ubgrade Reaction in Clayey Soil. Journal of Applied Science, 9; 9 (): Zhemochin B. N., Sinityn A. P. Practical method of calculation for beam and lab on elatic foundation without uig the Winler hypothei. Mocow: Gotroyizdat; About the author IGNACIO VILLALON FORNS Mater degree tudent Kauna Univerity of Technology, Department of Building Structure. Main reearch area Calculation and analyi of building tructure Adre Studentu t. 48, LT-51367, Kauna, Lithuania Tel.: mail: naxo. villalon@gmail.com DIVIDAS MARTINAVIČIUS Mater degree tudent Kauna Univerity of Technology, Department of Building Structure. Main reearch area Calculation and analyi of building tructure Adre Studentu t. 48, LT-51367, Kauna, Lithuania Tel.: mail: deivida. martinaviciu@tu. edu MINDAUGAS GRICIUS Mater degree tudent Kauna Univerity of Technology, Department of Building Structure. Main reearch area Calculation and analyi of building tructure Adre Studentu t. 48, LT-51367, Kauna, Lithuania Tel.: mail: mindauga. griciu@tu.edu ŠARŪNAS KLPŠA Lecturer Kauna Univerity of Technology, Department of Building Structure Main reearch area Reinforced concrete. Structural analyi. Addre Studentu t. 48, LT-51367, Kauna, Lithuania Tel.: mail: aruna. elpa@tu.lt MINDAUGAS KASIULVIČIUS Director JSC Smailui liauta Main reearch area Timber tructure. Structural analyi Adre Piliaalnio t. 3, LT-464 Kauna, Lithuania Tel.: mail: mindauga aiuleviciu@ yachoo.com