Build-up Virtual Laboratory for Reinforced
Concrete Structures to Enhance Understanding
Design Requirements
Hwang, Young Kwang
Deressa, Adeba Abera
Dept. Civil and Environmental Engineering
Yonsei University
Seoul, Korea
Dept. Civil and Environmental Engineering
Yonsei University
Seoul, Korea
Bolander, John E.
Lim, Yun Mook
Dept. Civil and Environmental Engineering
University of California Davis
Davis, USA
Dept. Civil and Environmental Engineering
Yonsei University
Seoul, Korea
yunmook@yonsei.ac.kr
Abstract—In this paper, we are trying to provide a simulation
tool to find the different failure behavior of reinforced concrete (RC)
structures with various design conditions. For example, design code
asked designers/students to make distribution of re-bars for several
numbers rather than one re-bar in the designed beam. Students can
estimate the total amount of reinforcement cross sectional area by
simple calculation, but students have to distribute the total amount
area of re-bars to several numbers of re-bars with small diameter. In
this requirement of the code, the students who learn RC structure
design at the beginning stage are not easy to understand from
theoretical point of view. However, they can easily learn, if they have
hands on experience like real experiments or numerical simulations.
Here, the real experiments for RC structures are required a lot of
time and cost. Therefore, if a realistic simulation tool, so-called
‘Virtual RC Structure Lab’, is provided for engineering educational
purpose, students could have a chance to learn from virtual hands on
experience for RC structure design.
show them all about why the design requirements are asked. So,
it is the main reason why the experimental work for
engineering studies are essential curriculum in undergraduate
courses.
Keywords—virtual laboratory; RC structures; failure behavior; hands
on experience learning
In this paper, we are trying to provide such a RC structure
laboratory virtually to educate undergraduate engineering
students to have hands on experience rather than to learn from
the literature. It is the main purpose of ‘Virtual RC Structure
Lab.’ to provide not only table top calculation but also figuring
out with hands on experience. This time, we are going to
provide an example for the differences of failure behaviors of
RC beams. They are going to be tested under bending loads
with and without following requirements for the distributing rebars.
I.
INTRODUCTION
For civil engineering field, design requirements are one of
the main subject to study, but they are not easy to understand
for the beginning at early undergraduate engineering students.
Reinforced concrete structure design is one of these types of
studies in civil engineering. Designed procedure is not difficult
to the students, but some of design requirements are asked to
follow the rules suddenly at the end of design procedure.
Sometimes, the requirements are hard to understand because
they come into the design requirements according to empirical
results of studies. In Korea, old wisdom tells us that “Watching
a fact once is much better to understand compared to hear
hundred times.” That is the same word in education
methodology. Experience is the best learning method in the
education. If students made RC structures with and without to
meet design requirements, then the test results of the structures
However, it is hard to make experiments in some cases in
RC structure design class because it takes a lot of time and cost.
For example, one simple experiment for a RC beam needs at
least one and half month for preparing and curing before the
test as well as 2,000 USD for the material and labor cost.
However, these are only for the preparing specimens before the
loading tests. Also, the test set-up and technicians for the
loading tests are the other essential part of the experiments. If
we are trying to make a test for group of students, we need a lot
of time and money. Therefore, it is not easy to provide good
experimental environment to the students especially for
developing countries.
II.
NUMERICAL MODEL FOR SIMULATION
A. RBSN(Rigid-Body-Spring Network)
For concrete simulation, RBSN (Rigid-Body-SpringNetwork) model, one of random lattice models, was adopted.
In this model, concrete is considered as a collection of rigid
cells, so-called Voronoi cells. Between the cells, there is a
978-1-4799-8706-1/15/$31.00 ©2015 IEEE
20-24 September 2015, Florence, Italy
Proceedings of 2015 International Conference on Interactive Collaborative Learning (ICL)
(a) Generated point
(b) Delaunay
triangulation
(c) Voronoi diagram
Fig. 1. Mesh construction process [2].
Fig. 3. The process of virtual laboratory experiment.
Fig. 2. Reinforcing element within a two-cell assembly of a lattice
model [2].
spring set and it expresses the overall behavior of concrete [1].
General mesh generation process is described in figure 1.
B. Semi-discrete reinforcement
The re-bars of this simulation are modeled by semi-discrete
method ([2], [3]). The re-bar can be generated independent of
mesh configuration. The re-bar crosses facets of Voronoi
diagram and it contributes to the stiffness of the RBSN
elements. This semi-discrete method adds no additional
degrees of freedom to the system. Therefore, simulation can be
run more efficient way. Figure 2. shows the reinforcing
element within a two-cell assembly of a lattice model.
visualization of meshes. Then, users utilize these preprocessing information and set boundary conditions and
material properties to run analysis program. After analysis,
users can see the results (deformation, fracture, loaddisplacement curve, etc.) by simple post-processing program
with visualization capacity. These whole processes can be
easily executed by the users through the providing guideline.
In this study, we adopted the geometry and basic information
from the previous technical literatures for four points bending test
of RC beam ([4], [5]).
We simulated RC beam for three cases having same amount
of reinforcement area but different number of reinforcement (1, 3,
and 6, respectively).
Table I. shows the properties of concrete and re-bar used in
this simulation.
TABLE I.
Material
III.
VIRTUAL RC STRUCTURE LABORATORY
Our research team is performing a research that developing
RC structure analysis program for educational purpose. Now,
we are starting five years government funded project, EDISON,
to build the Virtual Laboratory. The general process of virtual
laboratory is described in Figure 3. This system can be opened
for the students and public. Students can access to the website
providing virtual laboratory platform from anywhere. The
Graphic User Interface (GUI) environment and guidelines will
be provided.
At the beginning of virtual experiments, users specify the
geometry of the specimens and this information used as input
in mesh generation process, so-called pre-processing including
Concrete
PROPERTIES OF MATERIALS
Property
Tensile strength, ft
3.29 MPa
Elasticity, Ec
25.4 GPa
Fracture energy, Gf
81.1 N/m
Poisson’s ratio, Ɗ
Re-bar
Magnitude
0.19
Elasticity, Es
186.0 GPa
Yield stress, fy
350.0 MPa
Figure 4. shows RC structure configuration, boundary
condition and its cross section which has different number of
re-bar. The total amount reinforcement area (As) is about 398
mm2. There are three simulation cases.
978-1-4799-8706-1/15/$31.00 ©2015 IEEE
20-24 September 2015, Florence, Italy
Proceedings of 2015 International Conference on Interactive Collaborative Learning (ICL)
Fig. 4. RC structure and boundary conditions (unit: mm).
Fig. 6. Fractrue configurations from the virtual experiment: a) with
single re-bar; b) with three re-bars; c) with six re-bars
Figure 6. shows how the students can check the analysis
results. The red colored surfaces and cells stand for fractured
surfaces and damaged cell during the loading test. The students
can check the state of virtual experiment even during analysis
running by using real time updated output files from analysis
program as like a real test. So, they can have hands on
experience from this experiment. Therefore, they can learn
from the simulation results what is the effects of re-bar
distribution and why design code asks such a requirement.
Fig. 5. RC beam mesh configuration: a) without re-bar; b) with single
re-bar (case 1); c) with three re-bars (case 2); d) with six re-bars (case 3)
At case 1, the diameter of a reinforcement is 22.52 mm and
the number of reinforcement is one. At case 2, the diameter of
a reinforcement is 13.00 mm and the number of reinforcement
is three. At case 3, the diameter of a reinforcement is 9.19 mm
and the number of reinforcement is six. Therefore, the total
reinforcement area is same for all cases, having different
number of re-bar.
After geometry of specimen is determined, the user can
make mesh configuration (figure 5.). Then, user uses this mesh
information as input to analysis program. Also, the properties
of specimen (Table I.) and boundary conditions (figure 4.) are
set before running the program.
IV.
CONCLUSION
In this study, we discussed the developing virtual
laboratory platform to help the understanding of students who
take RC design class. The RC beam test was conducted and the
results are what we expected. If the re-bars are distributed, the
damage also distributed wide manner. Therefore, students can
understand the reason why design code required to make rebars distribution in RC beam.
It is the first year of five year project for the ‘Virtual RC
Structure Lab.’ development for civil engineering students. It
will be implemented into a server which can be opened for
students and public step by step. So, students can access from
anywhere through the website and use the virtual experimental
978-1-4799-8706-1/15/$31.00 ©2015 IEEE
20-24 September 2015, Florence, Italy
Proceedings of 2015 International Conference on Interactive Collaborative Learning (ICL)
program at the end of 2015. So, they can experience and learn
from the simulated behavior of their own designed RC beam
intuitionally.
The effects of this developed ‘Virtual RC Structure Lab.’ in
terms of educational aspects could not provide this time
because it is not open to students. In near future, we might
provide a positive results for the assessment of the ‘Virtual RC
Structure Lab.’ for engineering educational purpose.
REFERENCES
[1]
[2]
[3]
[4]
ACKNOWLEDGMENT
This research was supported by the EDISON (Educationresearch Integration through Simulation On the Net) Program
through the National Research Foundation of Korea (NRF)
funded by the Ministry of Science, ICT & Future Planning
(2014M3C1A6038855)
[5]
J. Bolander, and S. Saito, “Fracture analyses using spring networks with
random geometry,” Engineering Fracture Mechanics, vol. 61, pp.569591, 1998.
M. Yip, J. Mohle, and J. E. Bolander, “Automated modeling of threedimensional structural components using irregular lattices,” ComputerAided Civil and Infrastructure Engineering, vol. 20, pp. 393-407, 2005.
K. Kim, J. Bolander, Y. M. Lim, “Failure simulation of RC structures
under highly dynamic conditions using random lattice models,”
Computer and Structures, vol. 125, pp. 127-136, 2013.
K. Kim, “Development and Application of Nonlinear Interface Link
Elements Within a Three-Dimensional Random Lattice Model,” Maters
thesis, Yonsei University, South Korea, 2005.
H. Lee, “Evaluation of structural performance and strengthening of
corrosion deteriorated reinforced concrete members,” ph.D. thesis,
Tokyo University, Japan, 1997.
978-1-4799-8706-1/15/$31.00 ©2015 IEEE
20-24 September 2015, Florence, Italy
Proceedings of 2015 International Conference on Interactive Collaborative Learning (ICL)