Plaxis Bulletin 35
Plaxis Bulletin 35
Plaxis Bulletin 35
Plaxis Bulletin
Issue 35 / Spring 2014
Ed
Comparison of Structural Elements Response in PLAXIS 3D and SAP2000
Page 4
of the finite element method in geotechnical
engineering practise and includes articles on the
practical application of the PLAXIS programs, 05 PLAXIS Expert Services:
case studies and backgrounds on the models 3D Modelling of a Building
implemented in PLAXIS.
Subjected to Earthquake
The bulletin offers a platform where users of
PLAXIS can share ideas and experiences with
Loading
each other. The editors welcome submission of
papers for the Plaxis bulletin that fall in any of 06 Comparison of Structural
Page 6
these categories.
Elements Response in PLAXIS
The manuscript should preferably be submitted 3D and SAP2000
in an electronic format, formatted as plain text
without formatting. It should include the title
of the paper, the name(s) of the authors and 12 Reliability of Quay Walls
contact information (preferably e-mail) for the
corresponding author(s). The main body of
Using Finite Element Analysis
the article should be divided into appropriate
sections and, if necessary, subsections. If any 16 3D Finite Element Analysis of
Page 12
Colophon
The Plaxis Bulletin is a publication of Any correspondence regarding the Plaxis For information about PLAXIS software contact
Plaxis bv and is distributed worldwide among Bulletin can be sent by e-mail to: your local agent or Plaxis main office:
Plaxis subscribers
bulletin@plaxis.nl Plaxis bv
Editorial board: P.O. Box 572
Erwin Beernink or by regular mail to: 2600 AN Delft
Ronald Brinkgreve The Netherlands
Martin de Kant Plaxis Bulletin
Arny Lengkeek c/o Annelies Vogelezang info@plaxis.nl
PO Box 572 www.plaxis.nl
Design: 2600 AN Delft Tel: +31 (0)15 251 7720
Jori van den Munckhof The Netherlands Fax: +31 (0)15 257 3107
Cover photo courtesy of CUR 211 (2013). Quay Walls, 2nd edition. Gouda
Editorial
The begining of 2014 was also the begining of The third users article describes the development
quite some new developments at Plaxis. We of a comprehensive three-dimensional finite
released the completely restyled PLAXIS 2D AE. element model for the Stata Center basement
Furthermore we are expanding our offices and are excavation (Cambridge, USA) using PLAXIS 3D
happy to announce the opening of the new branch 2012. The analyses highlight the effects of the
office in Houston TX, U.S.A., Plaxis Americas LLC. 3D excavation and support geometry on wall
You can read all about these and other news in the deflections and show a good agreement with
recent activities column. the measured response assuming undrained
conditions using the Mohr-Coulomb soil model.
Furthermore, in this 35th issue of the Plaxis
bulletin, we have again tried to compile interesting In addition there is a joint presentation about a
articles and useful information for you. In the project where Deltares and Plaxis worked together
New Developments column we will discuss some to set up a 3D non linear dynamic model of a
different developed features for applications in building interacting with the subsoil through its
rock in PLAXIS software over the last years, with pile foundation, for the assessment of the impact
a specific focus on the recent release of the new of man-induced earthquakes on infrastructures.
Swelling Rock Model. Plaxis provided assistance in setting-up the 3D
finite element model to evaluate the buildings
The first users article discusses the analysis of seismic performance under possible moderate
the response of a number of structural models seismic activity.
subjected to different loading conditions. The
goal of such a comparison is the assessment of We wish you an enjoyable reading experience and
the structural elements performance in PLAXIS look forward to receiving your comments on this
3D as compared to that obtained by the well- spring 2014 issue of the Plaxis bulletin.
known SAP2000, a widely used code for structural
analysis. An overall good match was obtained, The Editors
as such highlighting the possibility to use the
code PLAXIS 3D to perform both structural
and geotechnical calculations in soil-structure
interaction problems.
Starting as a finite element software package for geo-engineering applications in soft soil, PLAXIS has meanwhile evolved
to cover most geo-materials, ranging from soft soil to rock. This makes PLAXIS a convenient tool to analyse not only
embankments, foundations and excavations at shallow depths, but also applications in the deeper underground, like deep
tunnels and underground openings in hard soils and soft rocks as well as deep mining applications.
For the assessment of the impact of man-induced earthquakes on infrastructures, Deltares and Plaxis worked together to
set up a 3D non linear dynamic model of a building interacting with the subsoil through its pile foundation. Plaxis provided
assistance in setting-up the 3D finite element model to evaluate the buildings seismic performance under possible moderate
seismic activity. The main challenge of this project was the rather short time frame within which such FE analyses needed to be
carried out. Thanks to PLAXIS Expert Services, Deltares managed to deliver FEA results in an efficient and timely manner.
In this paper the response of a number of structural models subjected to different loading conditions is analysed with the
codes PLAXIS 3D and SAP2000. The goal of such a comparison is the assessment of the structural elements performance in
PLAXIS 3D as compared to that obtained by the well-known SAP2000, a widely used code for structural analysis. An overall
good match was obtained, as such highlighting the possibility to use the code PLAXIS 3D to perform both structural and
geotechnical calculations in soil-structure interaction problems.
Figure 3: Model M1: response of beam 6-7 under loading Figure 4: Model M1: response of beam 3-7 under loading
condition C2 in PLAXIS 3D and in SAP2000
Distributions of shear, bending moment and
condition C1 in PLAXIS 3D and in SAP2000
inflection for beams 6-7 (relative to loading
conditions C1 and C3) and 3-7 (for loading
condition C2) as calculated by the two codes are
In this example, defined model M1, as in the A linear-elastic constitutive law was adopted for shown in Figures 3, 4 and 5. This latter figure also
following ones, beams and columns are modelled these elements, whose parameters were selected reports the horizontal displacements along x
as one-dimensional elements of frame-type in consistently with the assumed reinforced concrete direction of column 1-2 under loading condition
SAP2000 and beam-type in PLAXIS 3D. This latter material (Table 1). C3.
element, differently from the frame type, is not
able to react to torsional actions. Both elements All the six displacement components were It is possible to note that the results calculated by
allow for deflections due to shearing as well as restrained at the base of the model in SAP2000. In SAP2000 and PLAXIS 3D are fairly coincident in
bending. an interaction problem, this condition simulates terms of shear, bending moment and inflection,
Figure 5: Model M1: response of beam 6-7 and column 1-2 under loading condition C3 in PLAXIS 3D and in SAP2000
The numerical model of this structure (model
M2) is coincident to model M1 in terms of beams,
columns and constraint conditions at the base.
of the necessary reduction of the moduli to match The diagonal elements of the frame were
the reference results obtained by SAP2000 is equal modelled in order to make them equivalent
to 10%, as such the adopted parameters are Ey = 1 to a building infill panel, adopting a simplified
GPa; Gyz= 416.7 MPa. version of a formulation proposed in the literature
(Panagiotakos and Fardis, 1996; Fardis, 1997). The
The same loading conditions previously analysed width of the cross bracings, bw, was defined with
for model M1were considered, namely C1 (taking reference to the expression of Mainstone (1971):
also into account the floor slab weight), C2 and C3.
bw = 0.175 ( h hw ) 0.4 dw (1)
The finite element mesh used for this model in where: d w is the diagonal length of the panel, hw is
PLAXIS 3D is similar to that defined in model the panel height and the parameter h is equal to:
M1; in SAP2000, on the contrary, the mesh of the
Ew t w sin( 2 )
model with isotropic slab was modified to make h = 4
(2)
it roughly equivalent to that defined in PLAXIS 4 Ec Ic hw
3D. This expedient is related to the fact that in where Ew and Ec are the Youngs moduli of the infill
SAP2000 the load of the floor slab is transferred to panel and of the reinforced concrete structural
the beams in correspondence of the mesh nodes, elements surrounding the panel, respectively;
therefore a similar finite element discretisation is is the angle formed by the diagonal of the infill
required in order to obtain consistent results by panel with respect to the horizontal axis; t w is the
the two different codes. panel thickness; Ic is the moment of inertia of the
columns adjacent to the infill panel. The values of
Figures 8, 9 and 10 show the comparison between these parameters are summarised in Table 3.
models M1 and M2 in terms of shear, bending
moment and inflection for beam 3-7 under loading The cross bracings were modelled as weightless
conditions C1, C2 and C3, respectively. Figure 10 one-dimensional elements reacting only to axial
also shows the horizontal displacements of column stress (denoted as truss elements in SAP2000 and
1-2 along x-axis. node-to-node anchor elements in PLAXIS 3D),
characterised by an axial stiffness equal to
Results demonstrate the good agreement K = Ew * bw * t w = 450000 kN. An elastic-plastic
between the structural responses obtained by constitutive law was selected for the elements to
the two different numerical codes. In general, it introduce a limit value of the tensile strength equal
is possible to observe an equivalent response to zero, aimed at neglecting tensile stresses for
of beam 3-7 under loading conditions C1 and the cross bracings.
C2 for model M2 too. As expected, the different
Figure 8: Model M2: response of beam 3-7 under loading assumption concerning the behaviour of the floor The response of model M3 was assessed by
condition C1 in PLAXIS 3D and in SAP2000 slab (i.e. isotropic or anisotropic) plays an essential considering the structural elements weight (beams
role in the intensity and distribution of shear, and columns) and a force of 20 kN applied at
bending moment and inflection. node 2 along x-axis (loading condition C4). Figure
12 shows a perfect match among the results of
In the anisotropic case, the structural element 3-7 the two models in terms of normal stress acting
is one of two main beams of the floor slab and it in column 3-4 and diagonal element 2-4; shear,
results to be more heavily loaded as compared to bending moment and inflection in beam 2-3;
what observed in the isotropic model, where all horizontal displacement in column 3-4.
the beams were equally loaded per unit of length.
Modelling a Spatial 3-Storey Frame with and
On the contrary, the different mechanical without Cross Bracings: Models M4(I) and M4(II)
hypotheses seem to have a barely relevant In this section the responses of two 3-storey
influence on the horizontal displacement of the frame structures subjected to horizontal loads
column: this should be due to the fact that in both are compared, the structures differing only for
isotropic and anisotropic cases the relevant shear the presence of cross bracings (Fig. 13). The inter-
stiffness Gxy assumes the same value, leading storey height is 4 m and the beams length is equal
to a similar head restrain acting on the column, to 4 m in x direction and 5 m in y direction.
therefore resulting in a correspondingly similar
displacement pattern. The numerical models of the open-frame structure
and that of the structure with diagonal elements
Modelling a 2D-Frame with Diagonal Elements: are denoted as M4(I) and M4(II). In the models
Model M3 beams and columns are represented by one-
The simple structure shown in Figure 11 is a dimensional elements (frames and beams in the
single-bay plane frame with cross bracings. two codes) and, for sake of simplicity, the floor
These elements are commonly adopted in slabs are modelled as linear-elastic-isotropic
numerical studies to account for infill panels (e.g.: elements of shell-type in SAP2000 and plate-type
Panagiotakos and Fardis, 1996). Those latter, in PLAXIS 3D. For both models the mechanical
although being non-structural components, properties of columns, beams and floor slabs
significantly contribute to the overall structural are those listed in Tables 1 and 2; the usual rigid
response in the in-plane horizontal direction, constraint conditions are assumed at the base of
leading to a generally stiffer behaviour as the frames.
compared to open-frame ones.
The equivalent width dw of the cross bracings,
In the corresponding numerical model, defined as modelled as node-to-node anchor and truss
model M3, the structural elements (i.e. beam and elements in PLAXIS 3D and SAP2000 respectively,
columns) are represented by frames and beams was defined using Eq. (1) and the same elastic-
in SAP2000 and PLAXIS 3D, respectively, and are plastic constitutive law assumed for model M3 was
characterised by the material properties listed in selected in this case.
Figure 9: Model M2: response of beam 3-7 under loading Table 1. The base of the frame is constrained as in
condition C2 in PLAXIS 3D and in SAP2000 all the other models. Both models were analysed under gravity loading
Conclusions
In the paper the response of a number of
structural models subjected to different loading
conditions was analysed by the finite element
codes PLAXIS 3D and SAP2000. The main Figure 10: Model M2: response of beam 3-7 and column 1-2 under loading condition C3 in PLAXIS 3D and in SAP2000
outcomes resulting from the comparison, carried
out in terms of stress and displacements, can be
summarised as follows:
beams and columns can be modelled with
frame elements in SAP2000 and beam elements
in PLAXIS 3D. The main difference in the ele-
ment formulations resides in the inability of
beam elements to react to torsional actions.
In fact, the release of torsional constrains in
SAP2000 produces perfectly matching results;
the floor slab can be modelled in SAP2000 by a
shell element or using a diaphragm constraint
combined with some additional vertical forces
at the top of the columns to simulate the effect
of the slab weight. In the first case an isotropic
behaviour is obtained, while in the latter a more
realistic response is reproduced, as it allows to
account for the higher stiffness observed in the
warping direction. A plate element is instead
available in PLAXIS 3D. The use of an isotropic
formulation allows to nicely reproduce the
response of the shell element, while an aniso- Figure 11: 2D frame with cross bracings
tropic model should be selected to fit, after
a careful calibration of its elastic parameters,
the response of the more advanced scheme of
SAP2000;
infill panels can be modelled in a simplified
manner as cross bracings, whose characteristics
were obtained using the formulation proposed References
by Mainstone (1971). Truss and node-to-node 1. M.N. Fardis, 1997. Experimental and numeri-
anchor elements were used respectively in cal investigations on the seismic response of
SAP2000 and PLAXIS 3D, leading to perfectly RC infilled frames and recommendations for
consistent structural responses. code provisions. Report ECOEST-PREC8 No. 6.
Prenormative research in support of Eurocode
This study should be considered as a preliminary 8.
step towards more complex soil-structure 2. R.J. Mainstone, 1971. On the stiffnesses and
interaction problems, which indeed require a strengths of infilles frames. Proc. Inst. Civil.
good level of confidence in the use of structural Engineers, iv 7360s: 59-70.
elements in 3D analyses with PLAXIS. 3. T.B. Panagiotakos and M.N. Fardis, 1996.
Seismic response of infilled RC frames struc-
Acknowledgements tures. 11th World Conference on Earthquake
Special thanks to Ph.D. Eng. Francesco Tucci for Engineering, Acapulco, Mxico, June 23-28.
his helpful support during this research activity. Paper No. 225.
Figure 12: Model M3: responses of column 3-4, beam 2-3, and diagonal element 2-4 under C4 load condition in PLAXIS 3D and
in SAP2000
Figure 14: Models M4(I) and M4(II): comparison between horizontal displacements obtained in PLAXIS 3D and in SAP2000 with
(on the right) and without (on the left) cross bracings.
Authors: H.J. Wolters, K.J. Bakker and J.G. de Gijt, Delft University of Technology. The Netherlands
During the last years the Finite Element Method (FEM) is increasingly applied in the design of quay walls. Especially in
case of quay walls with relieving floors and bulk-storage as surcharge load, sub-grade reaction models are limited in their
accuracy of modelling the situation. The Finite Element Method often is the only option to more detailed design calculations
of quay walls. In the recent years the introduction of Eurocode and the increasing use of Finite Element analysis for design
calculations has triggered the update of the CUR Quay walls handbook CUR 211. The latter second edition has recently been
published. In advance of this second edition it was decided to look into more detail into the combination of FEM analysis in
combination with the Eurocode which lead to the study that is described in this article. In order to infer a more fundamental
base for the design method with FEM, two quay walls were examined to check the applicability of the existing FEM design
method of the Dutch Handbook Sheet Pile structures (CUR 166) on quay walls with relieving floor. Furthermore, it was checked
whether the current partial safety factors needed to be adapted. This research is done by performing probabilistic FEM
calculations. The First Order Reliability Method is incorporated in the software Prob2B (Courage & Steenbergen, 2007) to
perform the calculations. It appeared that using the design method of CUR 166 for quay walls with relieving floor leads to an
underestimation of the reliability of the structure. Therefore it is advised to adapt the design method. Furthermore, differences
in partial safety factors are proposed to reach the required reliability index.
Fig. 2: Horizontal shear forces due to bulk-storage, that will increase the anchor force, are
difficult to model with sub-grade reaction model Fig. 3: Quay wall with relieve platform, modelled in PLAXIS
that is used to obtain the reliability indices and the main focus is on this second analysis. The description of the unloading behaviour of the soil
partial safety factors and compares the results model is based on the quay wall from Fig. 1. The behind the wall and gives a description of the
from these calculations with the 2003 edition of quay wall is anchored by a double anchor that soil deformations under the relieving platform.
CUR 211. must guarantee a top displacement of less than In contrast to the normal design procedure, here
50 mm. The combi-wall consists of tubular piles for the probabilistic analysis, mean values of the
Quay Walls and Failure Mechanism with 1420 mm diameter and 18 mm wall thickness. parameters where used. Normally, characteristic
The research is done for two different types of In between the piles there are three sheet-piles values would need to be applied, according to
quay wall, modelled in Plaxis. To begin with, an with profile AU20. The wall is excavated till NAP -19 the Eurocode. The difference between mean
anchored sheet-pile with two different sheet-pile m which implies 24 m retaining height. A bollard values and characteristic values was discounted
lengths (21m and 23m) was analysed. The sheet- force of 70 kN/m and a surcharge load of 40 kN/m2 for afterwards when partial safety factors where
pile is anchored 2 m below ground level (ground behind the quay wall are taken into account. The derived.
level is NAP) and has an AZ36-700N profile. The level of the top of the quay wall is NAP +5,0 m.
wall is excavated till NAP -12 m and a surcharge The soil configuration is based on Maasvlakte As a starting point for the analysis the FEM
load of 30 kN/m2 is present. The upper sand layer conditions. The upper sand layer reaches till procedures, as described in CUR 166, were
reaches till NAP -10 m. Below there is a clay layer NAP -8,50 m. Below there is a clay layer till taken. The analysed failure mechanisms of these
till NAP -15 m followed by another sand layer. The NAP -11,0 m, a sand layer till NAP -19,0 m, another structures are anchor failure in tension (ULS), wall
soil and structural parameters can be found in clay layer till NAP -22,0 m and Pleistocene sand. failure in bending (ULS), soil mechanical failure
the report of Wolters (2012, pp. 83-84). This first The soil and structural parameters can be found in (ULS) and excessive deformations (SLS).
configuration was used to check the method. the report of Wolters (2012, pp. 137-138). For each failure mechanism a reliability function is
defined of the form:
Secondly, a heavier quay wall with relieving The PLAXIS Hardening Soil model was used to Z = Resistance(R) Solicitation (S),
floor was modelled; see Fig. 3. In this article model the soil, because this enables a better which implies that failure is assumed for Z<0. The
dx
i
From the derivatives for each variable an
influence coefficient, i, can be determined by:
dZ
dui
i = 2 The sum of i2 is equal to 1.
dZ
dxi
For each parameter a possible design point
value can be determined by:
Fig. 4: Example of a plastic point plot in the design point of wall failure in bending (Red: Mohr-Coulomb point, Green: Hardening
X i = i i x ,i point, Blue: Cap and Hardening point)
This procedure is repeated by iterating with
the new obtained parameter values instead of
the initial mean values. After some iterations, From the output of Prob2B partial safety factors Output
convergence may be found and the design can be derived using the formulas: For each FORM calculation output is generated
point and corresponding and i can be by the software. Table 1 is an example of the
1 + 1.64Vi
determined. For the failure mechanisms the Z k ,S = (load) and output for the limit state function of wall failure
1 i Vi
function should approach zero. in bending. The table includes the variation
1 1.64Vi coefficients (input) the influence factors, design
This FORM procedure is incorporated in Prob2B. k ,R = (resistance), point values and the failure probability (reliability
1 i Vi
However, not all stochastic parameters can be index). When implementing the design values
included. Variations in surcharge loads, water The coefficients of variation for the soil variables a plastic point plot can visualize the failure
levels and bottom level (dredging depth) need to and their correlations with other variables are mechanism.
be made manually. With these manual variations derived from a database of Rotterdam Public
dZ/dx is calculated and from there the uncertainty Works, containing 3000 tri-axial tests and added An example of such a plot is given in Fig. 4. In this
in those parameters can be incorporated in the by information from the Dutch national annex to plot it can be seen that wall failure occurs due to
reliability index and influence factors can be NEN-EN 1997 (former NEN 6740). For the structural failure of the soil elements at the lower part of
derived. variables the prescriptions of the Joint Committee the piles. This soil failure leads to a reduced fixing
on Structural Safety (2002) are followed. moment which causes an increase in the maximum
relatively high prescribed target reliability in CUR Finally, the uncertainty in anchor parameters can
calculated CUR 211 211 (Wolters, 2012 pp. 170-174). contribute significantly to the anchor failure.
Zhandos Y. Orazalin, Ph.D. Candidate, Department of Civil & Environmental Engineering, Massachusetts Institute of Technology, Cambridge, USA
Andrew J. Whittle, Professor of Civil & Environmental Engineering, Massachusetts Institute of Technology, Cambridge, USA
This article describes the development of a comprehensive three-dimensional finite element model for the Stata Center
basement excavation (Cambridge, USA) using PLAXIS 3D 2012. The project involved a complex sequence of berms, access
ramps and phased construction of the concrete mat foundation. Lateral wall movements and building settlements were closely
monitored throughout construction, while photos from a network of webcams located around the open-plan site provided
a detailed time history of the construction processes. The analyses highlight the effects of the 3D excavation and support
geometry on wall deflections and show a good agreement with the measured response assuming undrained conditions using
the Mohr-Coulomb soil model.
The measured performance during the actual BBC (Lower) MC (UD) -17.0 19.3 61 - 93 - 75 0.3 0.6
excavation exceeded the allowable wall Glacial Till MC (D) -29.0 22.0 - 43 385 0.3 1.0
deformations (38mm) prescribed at the start of
the project with maximum lateral movements Table 1: Soil properties (*D = drained, UD = undrained)
east sides, at the depth of 1.8 m. A typical subsurface profile documented - it was constantly photographed,
2. two levels of corner bracing, and underlying the Stata Center in the middle of the monitored, and described in daily field logs, as
3. two levels of raker supports on the north side. site would consist of 3.4 m of fill, 1.8 m of organics, well as recorded on webcams located around the
Tiebacks were installed at an angle of 20 degrees 4.3 m of sand, 26 m of clay, and 4.6 m of glacial construction site. Using these data, it was possible
from the horizontal at El. 3 m, El. 0.3 m, and El. 3 till (Figure 2). The principal stratum is the marine to create a full three-dimensional numerical model
m and preloaded from 498 to 569 kN. Two levels of clay (Boston Blue Clay), which can be sub-divided of the actual excavation with respect to the time
corner bracing consisting of 91-cm-diameter pipe into an upper overconsolidated clay crust and a frame of construction sequence.
struts were installed at El. 3 and El. 3 m. lower lighly-overconsolidated unit. The clay has
low hydraulic conductivity and is modeled as an Olsen (2001) developed a series of 3D geometric
The City of Cambridge prohibited the installation Undrained Elastic - Perfectly Plastic (EPP) material models to represent the construction process by
of tiebacks beneath the Vassar Street such that with the undrained shear strength that ranges reconciling daily field reports, photographs and
two levels of inclined raker bracing (at El. 3 and from a minimum value, su = 60kPa at El. -16m to time-lapse of the project. Figure 4 illustrates the
El. 3 m) were used along the North side of the a maximum, su 90kPa at the base of the clay. process of converting the geometric information
excavation. The raker bracing consisted of 91 cm The other layers are also represented by the EPP into Phases used in the development of the 3D
in diameter pipe struts extending from embedded (Mohr-Coulomb) model. Table 1 illustrates soil finite element model. Project data from project
plates in the diaphragm wall to kicker blocks properties based on the subsurface exploration drawings were initially used to construct a CAD
embedded in the concrete mat foundation (Figure program. model of the support system. This information
1). was then used to create a base case model within
Model Description PLAXIS 3D. The excavated surface geometry is
Site Characterization and Soil Properties The excavation for the Stata Center has a complex obtained from the models reported by Olsen
The site is located at the eastern part of the geometry and variety of structural support (2001) that are converted into a set of tetrahedral
MIT campus in Cambridge, Massachusetts. The systems which makes the project challenging to elements using mesh tessellation operators in the
ground surface is approximately level at El. +6 m, model. However, the uniqueness of this project CAD program. These are then imported into Plaxis
and the groundwater table is in the overlying fill is that the excavation process was very well 3D as soil clusters that represent the excavation
Figure 5: Output of the phase April 25, 2001 in PLAXIS3D (vertical displacements) and corresponding photo of the construction site
planes that intersect at the wall center (Figure 7). corner. Nevertheless, the base case results are in element analysis can be effectively used for such
particularly good agreement with wall deflections complex excavation projects.
Figure 6 presents comparisons between the along the tieback-supported South wall and in
computed and measured wall deflections for the close agreement with maximum deflections at the References
11 inclinometers located around the perimeter center of the raker-supported North wall. 1. Hewitt, R. D., Haley, M. X., Kinner, E. B. (2003).
(Figure 1) at 4 stages of construction (spanning Case History of Deep Excavation on an Urban
the period from mid-January to June 2001). The Conclusions Campus. Proc., 12th Panamerican Conf. on Soil
inclinometers can be sub-divided into sections The application of a full 3D analysis in PLAXIS Mechanics and Geotechnical Engineering, Soil
where the wall is supported by tieback anchors 3D 2012 to the Stata Center excavation project Rock America. Boston.
(SC-10, SC-08, SC-07, and SC-04), corner bracing has been demonstrated. In order to capture the 2. Olsen, M. B. (2001). Measured Performance of
(SC-11, SC-09, SC-06, SC-05 and SC-03) and raker 3D effects of soil and support system responses a Large Excavation on the MIT Campus. SM
supports (SC-02, SC-01). from a non-uniform excavation process, complex Thesis, Department of Civil and Environmental
shapes of soil volumes were extruded based on Engineering, Massachusetts Institute of
In general, the patterns of measured wall the photographs and excavation plans using Technology, Cambridge, MA.
deflections are very well described by the base CAD. The non-uniform soil excavation resulted 3. Orazalin, Z. Y. (2012). Three-Dimensional Finite
case finite element model. The results are within in the three-dimensional effects which were Element Analysis of a Complex Excavation
5-10mm of the measured maximum and toe well-captured by the 3D model predictions. The on the MIT Campus. SM Thesis, Department
deflections of the diaphragm wall at the end of analysis results show a good agreement with the of Civil and Environmental Engineering,
construction (Phase 35), with the noted exception measured data and provide keys to explain many Massachusetts Institute of Technology,
of conditions at the NW and NE corners of the features of the observed performance including Cambridge, MA.
site (SC-11, SC-01 and SC-03), where measured the differences in diaphragm wall deformations 4. Orazalin, Z. Y., Whittle, A. J., & Olsen, M.
maximum wall deflections are 20mm higher associated with sections supported by tieback B. (2014) Three-dimensional analyses of
than the numerical predictions. The most likely anchors, raker beams and corner bracing. The excavation support system for Stata Center
causes influencing the results are the ground usage of a relatively simple constitutive soil model basement on MIT campus, in review ASCE
loss during construction of the wall panels and (within the undrained conditions) was sufficient Journal of Geotechnical and Geoenvironmental
lack of preloading of the 2nd level corner bracing due to the overconsolidated state of the marine Engineering.
prior to final excavation of berms in the NE clay. The study has shown that the full 3D finite
Phase 3: Phase 3:
Excavation EL. -4.3m Excavation EL. -6.4m
Product updates: PLAXIS 2D AE time-dependent anisotropic swelling of rocks. In improvements by grout injection, comparing
Early 2014 the PLAXIS 2D Anniversary Edition was the new developments column at the beginning solutions obtained with FE and analytical analyses.
released. The user interface of PLAXIS 2D AE has of this bulletin you can read more about this new The Notable prize went to Jasper Sluis for his
been restyled to follow the flexible and easy to use model. validation of the 2D embedded pile row feature.
workflow of the PLAXIS 3D program. In this new His article was already available in the previous
graphical user interface the geometric modelling A look back: European Plaxis Users Meeting 34th edition of the Plaxis Bulletin. You can look
and staged construction is integrated allowing The European Plaxis Users Meeting 2013 was back at all our issues of the Plaxis Bulletins over
for quick and easy switching between input held in Karlsruhe, Germany. Not only was it the the years on our site at www.plaxis.com/bulletin.
(geometry) and calculation phases. 20th edition of the meeting, Plaxis bv was also The last article by Christian Elescano will be
celebrating its 20th Anniversary. For this reason included in an upcoming bulletin, so keep an eye
Other new and improved features include; we had extra social activities including some food out for it.
Command Line and Commands Runner, borehole and drinks to commemorate the occasion. We
wizard for soil modelling, CPT import, Remote also announced the winners of the master thesis All in all it was a great moment to look back at 20
Scripting API with python wrapper, Phases competition. The committee members were years of Plaxis bv and an even longer history of our
Explorer and Phases Window, and much more. Erjona Engin, MSc. (Plaxis bv) Dr. Claire Heaney software. You can also check out the video on the
Furthermore we also deliver a conversion tool, (Cardiff University), Dr. Bert Schdlich (TU Graz), evolution of PLAXIS software on our website.
which proved to be very versatile. In case you run Dr. Nallathamby Sivasithamparam (NGI), and Dr.
into a conversion issue, please let us know and we Phil Vardon (TU Delft). Plaxis Americas LLC
will update this conversion tool accordingly. A big step for our North American operations was
The winner was Zhandos Orazalin with his the formation of a US based company by Plaxis,
There are also two new user defined soil models research on the use of 3D FE analyses in PLAXIS Plaxis Americas LLC. This new company makes
available. The first is an update for the Visco- 3D to simulate ground deformations, pore doing business with Plaxis easier and faster, and
Elastic Perfectly Plastic Model. It is a simple and pressures, and diaphragm wall deflections. In underlines the commitment of Plaxis to the North
robust model which can be used to model time- this issue of the Plaxis Bulletin you can read his American geotechnical community. Sales and
dependent behaviour (creep and relaxation) of article entiteled 3D Finite Element Analysis backoffice activities for all US and Canadian clients
various materials. The second is the new Swelling of a Complex Excavation. The Runner-up was are now coming from this new Houston based
Rock Model, which can be used to simulate the Christian Elescano with his study on soil ground company.
Hong Kong
PLAXIS AsiaPac in association with our Hong
Kong agent, Solution Research Centre, conducted
a series of Entry and training workshops in
March 2014. This series of modular training
The past fall and winter saw Plaxis exhibit at a for our North American courses (which stacks with workshops offered greater flexibility and allowed
variety of national and regional geotechnical VIP discount) so make sure to register early to get our valued users to subscribe to a structured
events this illustrates the diverse geotechnical the best price! training program. Module HKG 1 on the topic of
sectors in which Plaxis is being used (e.g. DFI, Dam Introduction to PLAXIS 2D was held on 23 rd of
Safety). At CGSs GeoMontreal a lot of interest in News from Plaxis Asia-Pacific February. This was followed by Module HKG 3
PLAXIS came from existing and potential users Plaxis AsiaPac started the year by conducting a which is on the topic of Geotechnical Modelling.
from all across Canada. And more recently, at series of technical seminars and workshops in Asia.
ASCEs Geo-Congress, the new PLAXIS 2D AE We will be back in the second quarter of the year
version was demonstrated to numerous engineers. India to conduct these modules again with the addition
Well continue to visit and exhibit at events In association with our Indian agent, Ramcaddsys, of advanced application modules.
across North America in 2014, so check the list of we conducted a series of lectures on the
upcoming events at www.plaxis.com/events to see modelling of Geotechnical problems. Singapore
when and where you can meet us in person. We PLAXIS AsiaPac in association with Norwegian
look forward to meet you! In collaboration with the Civil and Ocean Geotechnical Institute conducted a one-day
Engineering Departments from IIT-Madras, seminar on Offshore Geotechnical Modelling
The upcoming months will see two educational two seminars were conducted on the 11th and using FEM on the 1st of April 2014. The seminar
opportunities: a standard course in New York 12 th February 2014. The seminars were on the was well received and attended by users from the
in June, and an advanced course in Houston in application of PLAXIS 2D and 3D programs. Offshore industry. This is the first of our annual
October. These well-balanced courses are led The seminars centered on the modelling seminar on the subject of Offshore Geotechnics.
by a course leader from Plaxis and have in-depth of excavations, foundations, tunnelling and We look forward to conducting this event in 2015.
contributions from American professors. And for earthquake analysis.
the first time we are offering early bird discounts
www.plaxis.com
Plaxis bv Computerlaan 14 Plaxis AsiaPac Pte Ltd 16 Jalan Kilang Timor Plaxis Americas LLC 2500 Wilcrest Drive, St. 300
Tel: +31 (0)15 2517 720 2628 XK Delft Tel: +65 6325 4191 #05-08 Redhill Forum Tel: +1 (650) 804 4729 Houston TX 77042
info@plaxis.com The Netherlands asiapac@plaxis.com 159308 Singapore americas@plaxis.com U.S.A.