Effect of Type of Earthquake Seismic Analysis of Concrete cube shaped Tanks Buried According to the Interaction of Soil Structure

Transcription

1 1 Effect of Type of Earthquake Seisic Analysis of Concrete cube shaped Tanks Buried According to the Interaction of Soil Structure R. Naderi 1, A. Yosefi Saangany, M. H. Talebpour 3 1 Assistant Professor, Shahrood University of Technology, Shahrood, Iran MSc Student, Departent of Civil Engineering,Islaic Azad University, Arak Branch, Iran 3 PhD. Student, Departent of Civil Engineering, Shahrood University of Technology, Iran Abstract Tanks are generally buried structures to store and aintain large aounts of fluids are used. Therefore play an iportant role in systes engineering and should play a vital arteries. Failure and failure of such structures after the earthquake, Various losses such as loss of econoic, environental, etc. This search has led the design and analysis of iportant reservoirs are buried. In this paper, the influence of earthquake tie history as the seisic behavior of buried tanks are considered. Thus the three diensional reservoir odeling concrete cube to the software Abaqus Effect of the Northridge earthquake, and Elcentro, Chi Chi Considering the interaction of soil and structure has been studied. The process for odeling the effect of soil structure interaction and wave propagation phenoena in the soil around the tank, and direct ethod of solving viscous absorbing boundary is used. Finally, draw diagras tank wall deforation and stress, the effect of the earthquake record has been evaluated. Key words: Tie history analysis, buried tanks, and soil structure interaction, cube shaped tanks. 1. Introduction Soe structures are repositories for storage and aintenance of various liquids such as water, oil products and cheicals are used. Such structures and place to suit the application used, in various fors such as cylindrical, cubic, etc., are produced. Status of deployent of tanks, buried three general groups, land and air are divided. Meanwhile, buried tanks at the refinery due to the use and urban water supply networks have a particular iportance. Therefore, failure of such structures due to lack of observation, the following general effects are irreparable. Buried oil tanks and daage caused cheical spill aterials and environental pollution, and soe fires are vast. Destruction of water caused the buried tanks destroyed a large part of their environent due to phenoena such as earth, etc. will be settlent. Therefore, the design and analysis of such structures is iportant and ust be given the ost iportant factors influencing, the reservoir during the service carried out. One of the is the earthquake force in the design and analysis of buried tanks should play an iportant role to play. This issue has caused in the past years, any researchers analyzed the effect of tanks buried under the earthquake forces are considered. The researchers one of the oldest Jacobsan [1] Is. After Jacobsan, Housner researchers also one of the oldest reservoirs in seisic analysis is. Housner In 1954 extensive research in the field of siple dynaical odel for the buried rectangular and cylindrical tanks start and noted []. Like other researchers after hi Lyser and Kuhleeyer Epstein [4] Kausel [5] Buried tanks and so the odeling was investigated. But always in the process odeling point of reflection for buried tanks, tank and surrounding soil Interaction of soil and the tank is. Aaron valuable inforation into action in the field of soil and structures related to previous researchers and their experients, the debate has gathered buried reservoir odeling [6] Most research in the field of soil structure interaction is based on the finite eleent analysis odels based on two-diensional tanks of various software are discussed [7-8] However, in soe cases, odeling is also considered [10-1]. In this paper, the seisic behavior of buried concrete cube shaped tanks, according to several earthquakes, such as Chi Chi, and Northridge Elcentro discussed. Reservoir analysis in the process of three-diensional odels have been used To a ore accurate assessent of earthquake-induced forces on the tank wall paraeters such as stress and deforation is achieved. For this purpose, the software ABAQUS The appropriate coputational capability based on finite eleent ethod has been used [13]. It is noteworthy that the present odeling of soil surrounding the reservoir is hoogeneous and to perfor analysis process, first under the environent of static force and the

2 weight placed coponents Selected records earthquakes, the effect is given. Modeling software based on sex, body, floor and ceiling of reinforced concrete tank of the type of behavior is considered linear. Finally, draw diagras concrete tank wall deforation and stress, influence earthquake analysis process has been studied. 1. Seisic analysis of buried tanks Different ethods for seisic analysis of tanks, there are generally two categories, static and dynaic analysis are suarized. Meanwhile, the dynaic analysis of both spectral analysis and tie history analysis is expressed. Tie history analysis of two odes, one in Another tie doain and frequency doain is perfored on. In dynaic tie history analysis, the effect of ground otion acceleration tie history as a site to be deterined. In this ethod, structural coponents directly affected by horizontal and vertical acceleration of ground otion is placed. So history analysis When required Geotechnical seisic studies at the site until this basis for site earth oving target, based on analysis of earthquake ground response should be deterined. Based on analysis of earthquake ground otion profile can then records the required spectru and can be calculated. This process Generally a coplex process and requires knowledge of various paraeters is [14]. In this paper tie history analysis in frequency doain is used. Thus the equations of otion is expressed as follows: M U C U K U M U t g (1) In relation to the above M ass atrix, U oentu atrix syste, C atrix depreciation U syste atrix syste speed, K syste stiffness atrix, U the atrix displaceent and t acceleration oveent of the earth syste [15]. To solve the equations of otion, there are different ethods coonly associated with the daping factor is reoved. But for ost siulation odels with actual depreciation syste ust be considered. Therefore, the total daping atrix of the syste can be expressed as follows [1]: C M K CF i () In relation to the above CF n atrix eleent n, fluid viscous daping and is the nuber of fluid eleents. Daping atrix for the extraction fluid, the relationship between strain rate and shear stress changes in tie according to the viscosity coefficient is used. In relation () Coefficients can be and In the general case be calculated based on the following relationship: i j j i i (3) i j 1 j 1 i j In this regard i and j Two-ode frequencies, respectively, and the ain reservoir and i and j Daping is related to it. With a choice of two ain frequencies 1 and Modal of analysis and consider a fixed percentage of daping, can be related based on the following two equations (3) and obtain relations dynaic analysis: n1 1 (4) 1 (5) Finally, the above equation, we will: 1 (6) 1 (7) 1 But the point discussed above reflect on the soil around the tank directly in the equations of otion is not observed. Soil around the tank constantly earthquake force on the structure and distribution of U g

3 3 earthquake waves is effective. Therefore, the process ust be buried reservoir seisic analysis of soil aterial reservoir and the surrounding soil structure interaction is considered..1 Soil Structure Interaction Generally, soil structure interaction phenoena of two structural failure in adherence surrounding soil deforation and the effect on the structural dynaic otion around the soil is. Several ethods of analysis and interaction of soil and structure are the ost iportant of these ethods in three ain groups: Under structure ethods, and ethods of direct solution ethod to solve coplex is seen. The ost widely used ethods, the direct solving ethod based on finite eleent ethod forulation is based. In other words, this ethod of soil and structural finite eleent ethod odel to help and then are analyzed together. One of Basic weakness of this ethod is that the odeling of soil and structural finite eleent ethod requires the nuber of degrees of freedo are any. Another ethod of solving the ajor probles of direct, alost all odeling environent that is unliited [16]. In other words, the reservoir and environent odeling, Displaceent at infinity is zero and no energy reflected fro the infinite reservoir reflected waves induced by the reservoir there. But virtually infinite odeling environent based on finite eleent ethods and software is not possible. Therefore, the liit should be considered as infinite and Infinite boundary conditions established in the present odel thus like to be reality. For this purpose, the direct ethod of solving the energy absorbing boundaries are used and the echanis of energy dissipation by these boundaries are siulated. In this study, using spring and daper odeling, energy absorbing boundaries Extree environent for siulation has been done. Accordingly, the lateral boundaries given environent odel, each node of the three eleents in the spring - daper orthogonal three directions perpendicular disruption has been used [10] Thus the waves return to the tank in the desired odel lateral boundaries, to be aortized. Other iportant issues involved in odeling the effects of soil structure interaction, the use of nonlinear soil behavior odel that can siulate. The ost general odeling ethod considering the effect of surrounding soil and soil structure interaction and wave propagation in soil is Alastvplastyk odel. This odel Include nonlinear behavior and can subit criteria for soil based on the subission for on the page level stress - strain considered. In this paper behavioral odels have been used Dragr Pragr approxiate Colob the criteria in 195 and is presented by Dragr Pragr. Yield criterion function Dragr Pragr is defined as follows: F J J k 0 (8) 1 D In relation to the above J 1 First constant stress tensor and the ain J D The second constant is the stress tensor difference. Values and k In relation (8), are odel paraeters; based on soil adhesion and friction to describe relations are calculated: sin (9) 33 sin 6C sin k (10) 3 3 sin In relation to the above and C Internal friction angle and cohesion, respectively, the soil is. Based on these criteria provide the surface boundary, the approxiate law of the ohair colub Dragr Pragr as aended by the von Misz criteria for subission to the hydrostatic stress effect has been. Advantages of standard Dragr Pragr can not duplicate the pattern of answers that are suggested colub ohair, cited. Behavioral odels are revealing the syste can be detailed three-diensional odeling reservoirs buried in the soil based software ABAQUS With Adoption of soil and structure interaction can be described [17].. Syste odeling software ABAQUS In this paper, odeling tank and surrounding soil environent software ABAQUS Three-diensional for and two separate classification has been defined and esh. In this paper for odeling the reservoir odel, the overall eleent Solid Hoogeneous type is used. Gender setting specifications

4 4 and based on the required tank (concrete) and other reservoir paraeters is done. In this siulation, the type of concrete reinforced with a linear behavior is defined. For Modeling soil around the tank, the type of Hoogeneous Solid Eleents, but based on soil paraeters settings are used. Eleents of a Solid Hoogeneous eleents and eight knot is that each node there are three degrees of freedo. Based on these eleents can be treated Elasto plastic Drakr Pragr through dynaic characteristics such as soil cohesion and soil internal friction angle, can be defined for nonlinear behavior. Thus to odel the behavior, the actual behavior of the syste is near. Models of three-diensional finite eleent software ABAQUS For cubic tank in the following for is provided. Figure - Three-diensional view of the tank and surrounding soil ABAQUS Figure 1 - Reservoir odeling eleent Classification in ABAQUS Figure 4 - Borders agnification and soil structure in Figure (3) Figure 3 - Plan cubic tank in the vicinity of soil 3.1 Dissected speciens and odel tanks In this paper cubic tank odel ade of concrete, seisic analysis for the study based on soil structure 3 interaction is used. Specific weight of concrete used in all the odels 400 kg / And odulus and 9 Poisson's ratio for concrete Elastsite the odol sequentially 0. and.1 10 kg / Been considered. In a given odel, the tank diensions External height 5.6 Been considered. Middle colun diensions for the desired odel, as the square 1 1 Is assued. Thickness of floor, walls and ceilings of the tanks 0.3 Is considered. As a single layer of soil around the tank and the length and transverse diensions And the deep 40 Defined that 30 Below the floor level around the tank and alost 5 Located on the overhead tank. Modeling soil surrounding the tank ade of soft soil density 1900 kg / 3 Used. Angle of internal friction and adhesion for a given soil, respectively, against 6 and 1400 kg / Been considered. On the other hand odulus and Poisson ratio respectively equal to the soil 0.5 and kg / Is in order. Daping coefficient equal to 5 percent on selected odels and values and According to calculations, respectively, against 0.13 and Been considered.

5 5 On the soil bed is rocky and earthquake records fro the lower boundary is applied to the syste. Earthquake acceleration tie history records as a basis Elcentro earthquake acceleration records, Northridge, and what the odel of what actions will be given. Fors (5) to (7) of the earthquake acceleration records selected shows. Figure 5 - acceleration Elcentro earthquake records Figure 6 - acceleration Chi Chi earthquake records Figure 7 - Acceleration Northridge earthquake records Considering the tie being, and analysis of large odels, for the calculation of the area of severe fluctuations present earthquake record is used. This profile earthquakes and tie of choice in odeling software ABAQUS Table (1) is visible. Table 1 - Profile of earthquake actions Earthquake Year earthquake Tie Used Chi Chi s 6.5 s تا Elcentro s 0.4 s تا Northridge s 0.5 s تا

6 6 As can be seen in Table 1, for all tie used the oentu apping given by equal to copare the effect of earthquake actions, be provided. s Considered is thus 4. Analysis of seisic vessels After the reservoir based on analysis of seisic acceleration records of earthquakes, the results described diagras for (8) has been ade. The charts have been tried, stress and deforation values at specific points according to changes in the height of the reservoir, to be evaluated, thus changes in earthquake types for values Stress and deforation of the tank wall according to the soil structure interaction ust be exained. Thus the for (8) graph deforation and stress changes in the concrete tank wall according earthquakes, Chi Chi, Elcentro, Northridge shows. Figure 8 - Graph axiu deforation and axiu stress on the tank wall As the chart for (8) can be seen, stress and deforation in the wall of the tank based on what what other earthquake earthquakes are ore selective. The reason can be discussed in axiu acceleration and proposed for discussion. As you know the ain characteristics of ground otion in three Sector overall scope, frequency content and duration of otion is seen. Dynaic range of criteria coon ground, which is based on the axiu acceleration of research done in 1973 (Avkavtv) And 1975 (Brad and Tryfvnak) intensity earthquakes are related. As the oentu apping presented in fors (5), (6) and (7) is observed, the axiu acceleration in the acceleration of earthquake records fro the Chi Chi accelerated the other peak acceleration of the apping is ore selective. Of On the other hand grab the base period of earthquake records of other earthquakes of Chi Chi is ore selective. These factors caused the earthquake to effect what aounts of what the concrete tank wall deforation and stress of the other earthquakes are given ore. Ter basis in accordance with the definition, the first and last tie exceed a value Threshold acceleration is generally equal to the threshold oentu 0.05g Be considered. Of course, other definitions by different researchers, the debate ove the earth for long-ter basis are presented. After the Earthquake Chi Chi, Accelerated exaination given by the apping, which can receive a axiu acceleration of earthquake Northridge Elcentro earthquake is higher But the base period for the acceleration of earthquake records Elcentro Northridge earthquake is higher. This is due to the axiu deforation and axiu values of stress for the concrete tank wall Elcentro earthquake Northridge earthquake is higher. In other words, coparing the axiu aount of deforation and stress for the concrete tank wall and the Northridge earthquake Elcentro iportant issue can be realized for earth oving. Ter effects of earthquake otion has the effect of frequency. Many physical processes such as reducing hardness, strength and so the nuber of cycles applied load or stress during an earthquake depends. A short-ter ove, even if Scope and agnitude is the axiu acceleration ay cycle ties to achieve a sufficient nuber of structures is not the final level. On the other hand a range of otion and acceleration and axiu average long-ter loading cycle, can be considerable daage to the structures created. Research criteria for the effect of frequency in the earth oving is done. Mc Gyvr and Hanks in 1981 for a ter relationship and agnitude of earthquake ground otion are presented. According to this relationship, duration of strong ground otion with the third root of seisic oent are related. Therefore, with increasing

7 7 duration of receiving strong ground otion, earthquake effects increase. It is worth noting however that other factors like the frequency content of the earthquake and its effects are involved. 5. Conclusion axiu acceleration of ground otion generally used to describe doain Gzfth be an effective ipact on the extent and effects of earthquakes, according to the other ain characters are strong ground otion. The base period usually is defined based on the acceleration threshold, the role and effects of the earthquake is. Effects of a large range of otion with a short ter uch of an average range of otion, but with enough tie, is less. dynaic response of buried tanks in addition to structural profile, the actions will depend on factors such as earthquake, priarily based on the ain characteristics of ground otion (aplitude, duration and frequency content) is described. dynaic response of buried tanks in the soil, any dependent on site characteristics and soil around the tank, so it is recoended in the seisic analysis of buried tanks, and soil structure interaction effects are considered. 6. References 1. Jacobsan,L.S, (1949), Ipulsive Hydrodynaic of Fluid Inside a Cylindrical Tanks and of Fluid Surrounding a Cylindrical Pier, BSSA.. Housner, G.W. (1954), Earthquake Pressures on Fluid Containers, Eighth Technical Report, Office of Naval Research, Contract N6 onr-11, Project Designation NR Lyser, J. and Kuhleeyer, R. (1969), Finite Dynaic Model for Infinite Media, Journal of Eng. Mech. Div. ASCE, EM4, pp Epstein, H. I. (1976), Seisic Dynaic of Liquid Storage Tanks, Journal of Structural Engineering Division, ASCE, Kausel, E. (1988), Local Transitting Boundaries, Journal of Eng. Mech. Div. ASCE, 114(6), pp Haroun, M. A. (1980), Dynaic Analyses of Liquid Storage Tanks, EERL, pp Rahi Zadeh, F.. And Khwaja Ahed Attari, N.., (138), "Evaluation of seisic behavior of buried tanks," Proceedings of Sixth International Conference of Civil Engineering, Isfahan University, Isfahan, Iran, May. 8. Khwaja Ahad Attari, N.., Rahi Zadeh, F.. And palate Verde, N.., (1383), "Study of dynaic pressure cap into the reservoir buried in the landslide phenoena and considering friction between soil and wall structure," Proceedings of The First National Congress of Civil Engineering, Sharif University, Tehran, Iran, May Mhdylv Trkany, H.. And Bastai, M.., (1388), "Effect of fluid type on seisic behavior of buried tanks," Proceedings First National Conference Engineering and infrastructure anageent, technical school capus Tehran University, Tehran, Iran, 5-7 Nov. 10. Shushtari, or. And the Taliban, AS., (1386), "Evaluation of seisic behavior of buried tanks," Proceedings Third National Congress of Civil Engineering, University of Tabriz, Tabriz, May. 11. Rahi Zadeh, F.. And Anshayyan, AS., (1387), "Study of three diensional seisic paraeters of the buried concrete tanks," Proceedings of Fourth National Congress of Civil Engineering, Tehran University, Tehran, May. 1. Mahin village, Reza. And Jacob, M.., (1387), "static and dynaic response of sei-buried tanks with soil aterial," Proceedings of Fourth National Congress of Civil Engineering, Tehran University, Tehran, May. 13. Abaqus, Analysis User's Manual Volue II, Analysis.

8 8 14. Kraer, S.L. (1996), Geotechnical Earthquake Engineering, First ed, Prentice Hall, New jersey. 15. Chopra, A. K., (1995), Dynaic of Structures, Theory and Applications to Earthquake Engineering, PRENTICE HALL, Englewood Cliffs, new jersey. 16. Geyer, W. B, and Wisuri, J. (000), Handbook of Storage Tank Syste codes, Regulations, and Design, Marcel Dekker Inc, Newyork. 17. Helwany, S. (007), Applied Soil Mechanics with ABAQUS Applications, First ed, John Wiley & Sons, Canada.