SIMULATION OF CONSTRUCTION PROCESSES WITHIN

VIRTUAL ENVIRONMENTS

Alcínia Zita Sampaio and Pedro Gameiro Henriques

Technical University of Lisbon, Dep. Civil Engineering and Architecture, Av. Rovisco Pais, 1049-001 Lisbon, Portugal

Keywords: Didactic models, Education, Virtual reality, Visual simulation.

Abstract: Three-dimensional geometric models have been used to present architectural and engineering works,

showing their final configuration. But, when the clarification of a detail or the constitution of a construction

step in needed, these models are not appropriate because they do not allow the observation of the

construction activity. Models that could present dynamically changes of the building geometry are a good

support on education in civil engineering domain. Techniques of geometric modelling and virtual reality

were used to obtain interactive models that could visually simulate the construction activity. The

applications explain the construction work of a cavity wall and a bridge. The models present distinct

advantage as educational aids in first-degree courses in Civil Engineering. The use of Virtual Reality

techniques in the development of educational applications brings new perspectives to the teaching of

subjects related to the field of civil construction.

1 INTRODUCTION

Normally, three-dimensional (3D) geometric

models, which are used to present architectural and

engineering works, show only their final form, not

allowing the visual simulation of their physical

increasing. The models concerning construction

needs to be able to produce changes of the geometry

of the project. The integration of geometric

representations of a building together with

scheduling data related to construction planning

information is the bases of 4D (3D + time) models

(Fisher, 2000). In construction field 4D models

combine 3D models with the project timeline (Retik,

1997). In addition Virtual Reality (VR) technology

has been used to turn 4D models more realistic

allowing interaction with the environment

representing the construction place. VTT Building

Technology has been developing and implementing

applications based on this technique improving a

better communication between the partners in a

construction project (Leinonen, 2003).

The use of 4D models just linked with

construction planning software or with

virtual/interactive capacities, concerns essentially

economic and administrative benefits as a way of

presenting the visual simulation of the “real

situation” of the work in several step of its

evolution. Those models are created for each

particular project and are mostly manipulated by the

principal designer or contractor.

Developing didactic models for students

concerns technical tasks, at a level that could be

understood by undergraduate students, but also

pedagogical judgments. In the present study, two

engineering construction work models were created,

from which it was possible to obtain 3D models

corresponding to different states of their shape,

simulating distinct stages in construction processes

(Sampaio, 2006). In order to create models, which

could visually simulate the construction work and

allowing interact with it, techniques of virtual reality

were used. The developed applications make it

possible to show the physical evolution of the work,

the monitoring of the planned construction sequence,

and the visualization of details of the form of every

component of each construction. They also assist the

study of the type and method of operation of the

equipment necessary for these construction

methodologies (Sampaio and Henriques, 2004).

2 DIDACTIC VIRTUAL MODELS

The aim of the practical application of the virtual

models is to provide support in civil engineering

326

Zita Sampaio A. and Gameiro Henriques P. (2008).

SIMULATION OF CONSTRUCTION PROCESSES WITHIN VIRTUAL ENVIRONMENTS.

In Proceedings of the Third International Conference on Computer Graphics Theory and Applications, pages 326-331

DOI: 10.5220/0001099403260331

 SciTePress

education namely in those disciplines relating to

bridges and construction process both in classroom-

based education and in distance learning based on e-

learning technology. Specialist in construction

processes and bridge design were consulted and

involved in the execution of the models in order to

obtain efficient and accurate didactic applications.

The selected examples are two elementary situations

of construction works: an external wall is a basic

component of a building and the cantilever method

of bridge deck construction is applied frequently.

The pedagogic aspect and the technical

knowledge are presented on the selection of the

quantity and type of elements to show in each virtual

model, on the sequence of exhibition to follow, on

the relationship established between the components

of both type of construction, on the degree of

geometric details needed to present and on the

technical information that must go with each

constructive step. Further details complement, in a

positive way, the educational applications bringing

to them more utility and efficiency. Namely, the

model of the wall shows the information concerning

construction activity of interest for students

corresponding to the geometric stage displayed in

each moment and the bridge construction model

shows particularly the movement of the equipment

in operation during the progression.

In addition, the use of techniques of virtual

reality on the development of these didactic

applications is helpful to education improving the

efficiency of the models in the way it allows the

interactivity with the virtual activity. The virtual

model can be manipulated interactively allowing the

teacher or student to monitor the physical evolution

of the work and the construction activities inherent

in its progression. This type of model allows the

participant to interact in an intuitive manner with the

simulated environment, to repeat the sequence or

task until the desired level of proficiency or skill has

been achieved and to perform in a safe environment.

Therefore, this new concept of VR technology

applied to didactic models brings new perspectives

to the teaching of subjects in the area of civil

engineering.

3 3D MODEL OF THE WALL

One of the developed applications corresponds to the

model of a masonry cavity wall, one of the basic

components of a standard construction. To enable

the visual simulation of the construction of the wall,

the geometric model generated is composed of a set

of elements, each representing one component of the

construction. The selection of elements and the

degree of detail of the 3D model configuration of

each component had the support of teachers and

specialist in construction. Using the EON Reality

system (EON, 2003), a system of virtual reality

technologies, specific properties were applied to the

model of the wall in order to obtain a virtual

environment.

3.1 Geometric Modelling of the

Construction Elements

The definition of the 3D model of an exterior wall of

a conventional building comprises the structural

elements (foundations, columns and beams), the

vertical filler panels and two bay elements (door and

window). Every element was modelled using the

AutoCAD system.

The structural elements of the model were

created with parallelepipeds and were connected

according to their usual placement in building

works. Because this is an educational model, the

steel reinforcements were also defined. In the model,

the rods of the reinforcements are shown as tubular

components with circular cross-section (

Figure 1).

Figure 1: 3D models of the wall components.

The type of masonry selected corresponds to an

external wall formed by a double panel of

breezeblocks, 11 cm, wide with an air cavity, 6 cm,

wide (

Figure 1). Complementary to this, the vertical

panels were modelled, comprising: the thermal

isolation plate placed between the brick panels; the

plaster applied to the external surface of the wall; the

stucco applied on the internal surface; two coats of

paint both inside and out and the stone slabs placed

on the exterior surface. Finally, two usual bay

elements, a door and a window, were modelled.

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3.2 Programming the Virtual

Construction

The completed model was then transferred to the

virtual reality system EON (as a design file with 3ds

extension). In this system, the visual simulation of

the building process of the wall, following a realistic

plan of the construction progress, was programmed.

For this effect, 23 phases of construction were

considered. The order in which components are

consecutively exhibited and incorporated into the

virtual model, represent realistically the physical

evolution of the wall under construction (Figure 2).

Figure 2: Exhibition of phases in building evolution.

During the animation, the student can control the

length of time that any phase is exhibited and

observe the model using the most suitable camera

and zoom positions for a correct perception of the

details of construction elements. It is possible to

highlight the component incorporated at each

new phase and to examine it in detail (Figure 3).

Figure 3: Elements displaced from the global model of the

wall.

Included, under the window in which the virtual

scene is exhibited, is a bar, which shows the

progress of the construction. Throughout the

animation, the bar is filled, progressively, with small

rectangles symbolizing the percentage built at the

time of the viewing of that particular phase, in

relation to the completed wall construction (Figure

3). Symbolically, it represents the bar diagrams

normally used on construction plans.

Simultaneously, with the visualization of each

phase, a text is shown (in the upper right corner of

the window, Figure 4), giving data relating to the

stage being shown, namely, its position within the

construction sequence, the description of the activity

and the characterization of the material of the

component being incorporated.

Figure 4: Presentation of text describing the exhibited

phase.

The development of the model was supported by

engineer specialist in construction activity. So this is

a guarantee that the model shows the construction

sequence in a correct way and the configuration of

each component was defined with accuracy. In this

educational application, it is important to include

details such as: bar showing the construction

progress; text with information concerning the stage

observed; the possibility to highlight elements from

the model; the accuracy of the reinforcements and

the way then connect inside the structural elements;

the details of the configuration of vertical panels and

components of the window and the door.

4 3D MODEL OF THE BRIDGE

The second model created allows the visual

simulation of the construction of a bridge using the

cantilever method. Students are able to interact with

the model dictating the rhythm of the process, which

allows them to observe details of the advanced

equipment and of the elements of the bridge (pillars,

deck and abutments). The sequence is defined

according to the norms of planning in this type of

work.

The North Viaduct of the Bridge Farm, in

Madeira, Portugal, was the case selected for

representation in the virtual environment (GRID,

1997). In cross-section, the deck of the viaduct

shows a box girder solution and its height varies in a

parabolic way along its three spans. The most

common construction technique for this typology is

the cantilever method of deck construction. This

Phase 5

Cementing the lintel

and foundation

Description:

Cement B30

Dimension of the

foundations:

100x80x40cm3

Dimensions of the

lintel cross section:

25x40cm2

Total volume of

cement:

0.98cm3

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328

method starts by applying concrete to a first segment

on each pillar, the segment being long enough to

install on it the work equipment. The construction of

the deck proceeds with the symmetrical execution of

the segments starting from each pillar. The

continuation of the deck, uniting the cantilever

spans, is completed with the positioning of the

closing segment. The support of specialist in bridge

designs was essential to obtain an accurate model,

not only on the geometry definition of components

of the bridge and devices, but also on the

establishment of the progression sequence and of the

way the equipment operates.

4.1 Geometric Modelling of the

Construction Environment

A computer graphic system which enables the

geometric modelling of a bridge deck of box girder

typology was used to generate, 3D models of deck

segments necessary for the visual simulation of the

construction of the bridge. Geometric description

can be entered directly into the deck-modelling

program. To achieve this, the developed interface

presents diagrams linked to parameters of the

dimensions, so facilitating the description of the

geometry established for each concrete case of the

deck. Figure 5 shows the interface corresponding to

the cross-section of the deck of the example.

The description of the longitudinal morphology

of the deck and the geometry of the delineation of

the service road, serving the zone where the bridge

is to be built is carried out in the same way. The

configuration and the spatial positioning of each are

obtained with a high degree of accuracy. Using the

data relating to the generated sections, the system

creates drawings and three-dimensional models of

the deck. To obtain the definition of the deck

segment models, consecutive sections corresponding

to the construction joints are used. The configuration

presented by the segment models is rigorously exact.

Figure 5 shows one of the segments of the deck.

To complete the model of the bridge, the pillars

and abutments were modelled using the AutoCAD

system. Then followed the modelling of the

advanced equipment, which is composed not only of

the form traveller, but also the formwork adaptable

to the size of each segment, the work platforms for

each formwork and the rails along which the

carriages run (Figure 6).

Figure 5: Interface to describe cross-sections and the 3D

model of a deck segment.

Figure 6: 3D models of the scaffolding and the advanced

equipment.

As, along with the abutments, the deck is

concreted with the false work on the ground, the

scaffolding for placement at each end of the deck

was also modelled (Figure 6). Terrain suitable for

the simulation of the positioning of the bridge on its

foundations was also modelled.

4.2 Programming the Construction

Animation

The attribution of virtual properties to the model of

the bridge was implemented by using the virtual

reality system EON Studio (EON, 2003). Once all

the 3D models of the construction environment had

been generated, they were transposed, in 3ds

extension data file format, to the virtual reality

system. The definition of the construction sequence

is based on a counter, which determines the next

action when a mouse button is clicked. The first

action consists of the insertion of the pillars in the

first scenario, which is composed solely of the

landscape. The next step is to place one of the

segments on the top of each pillar. After this, a form

SIMULATION OF CONSTRUCTION PROCESSES WITHIN VIRTUAL ENVIRONMENTS

329

traveller is placed on each segment. The

construction of the deck is defined symmetrically in

relation to each pillar and simultaneously (Figure 7).

For the simulation of the first cantilever segment

(in each span), the four form travellers, the

corresponding work platforms and the formwork

components are included in the scenario. Once the

first segments have been concreted, the construction

of the cantilevered deck takes place. In each phase,

two pairs of segments are defined.

For each new segment the following steps are

established: aising the form traveller; moving the

rails in the same direction as the construction

(relocating them on the latest segment to have been

concreted); moving the form traveller on the rails,

positioning it in the zone of the next segment to be

made; concrete the segment. Finally, the zone of the

deck near the supports is constructed, the false work

resting on the ground (Figure 8).

Figure 7: Placing the initial pillars and the advanced

equipment.

Moving the camera closer to the model of the

bridge and applying to it routes around the zone of

interest, it is possible to visualize the details of the

form of the components involved in the construction

process. In this way, the student can interact with the

virtual model, following the sequence specifications

and observing the details of the configurations of the

elements involved.

Figure 8: Movement of the advanced equipment and

concreting above the false work near the abutment.

In a real construction place of a bridge, for

security reasons, the student stays far from the local

were bridge is under construction, so they can’t

observe in detail the way of operation and the

progression of the construction. Interacting with the

model of the bridge in class or using their personal

computers they better understand what is going on

there in the construction zone.

5 LEARNING ASPECTS

The models are actually used in face-to-face classes

of disciplines of Civil Engineering curriculum:

Technical Drawing (1

year), Construction Process

year) and Bridges (5

year). The traditional way

to present the curricular subjects involved in those

virtual models are 2D layouts or pictures. Now, the

teacher interacts with the 3D models showing the

sequence construction and the constitution of the

modelled type of work. Essentially, the models are

used to introduce new subjects.

As in Technical Drawing, students have to define

and draw structural plants over the architectural

layouts, the virtual model of the wall helps to

explain the connection between the architectural

drawings and the structural solutions needed to

support the house configuration. Some indication

must be assumed when choosing a structural

solution in order to minimize the unpleasant visual

appearance in the interior of a house when structural

elements (beams, columns, ...) are included in it. The

students are 1

year degree, so they have some

difficulty to understand the spatial localization of the

structural elements and how they must be built and

located almost inside the walls. The relationships

between the architectural configurations and the

structural elements in a building are well explained

following the exhibition of the virtual construction

of the wall.

In the discipline of Construction Process, in

order to prepare students to visit real work places,

the teacher shows the construction animation and

explains some aspects of the construction process of

the wall. Namely, the way the net of irons is defined

inside a beam or a column and specially the

complexity of the relationship between the distinct

types of irons near the zone where the structural

elements connect each other (

Figure 9).

In order to clearly explain this issue related to the

structural elements, the iron nets were created as 3D

models with distinct colours, and they appear on the

virtual scenario following a specific planned

schedule. The type, sequence and thickness of each

vertical panel that composes a cavity wall are well

presented in the virtual model showing step by step

the relationship between each other. The

configuration detail of each element of a complete

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wall can be clearly observed manipulating the virtual

scenario of the construction.

Figure 9: Complex relationship between reinforcements in

the join zones of the structural elements.

The construction model of a bridge particularly

shows the complexity associated to the concrete

work of the deck bridge that is done in a symmetric

way. The model also shows in detail the movement

of the advanced equipment. In class, the professor

must explain way the process must follow that

sequence of steps and the way the equipment

devices operates. When the student, of the 5

year,

goes to the work place he can observe the

complexity and the sequence of construction

previously explained.

The students can also interact with those models.

For that, the models were posted on the Internet

pages of undergraduate courses in Civil Engineering.

The student will be able to interact with the

application EonX, which can be accessed at:

http://download.eonreality.com.

6 CONCLUSIONS

It has been demonstrated, through the examples

presented here, how the technology of virtual reality

can be used in the elaboration of teaching material of

educational interest in the area of construction

processes. The pedagogical aspects and the technical

concepts are attended on the elaboration of both

models.

The applications generated represent two

standard situations of constructions. The student can

interact with the virtual model in such a way that he

can set in motion the construction sequence

demanded by actual construction work, observe the

methodology applied, analyze in detail every

component of the work and the equipment needed to

support the construction process and observe how

the different pieces of a construction element mesh

with each other and become incorporated into the

model.

These models are used in disciplines involving

construction in courses in Civil Engineering and

Architecture. They can be used in classroom-based

education and in distance learning supported by e-

learning technology.

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