Design and Implementation of an Integrated Structural Design System.pdf

Design and Implementation of an Integrated Structural Design System

Chee Kyeong Kim 1 , Si Eun Lee 2

1 Professor, Sunmoon University

2 Professor, Baekseok College

Abstract

Rational data modeling is prerequisite to the computerization of design works and the use of design

information in the following works such as cost estimation and construction. Particularly, structural design of

buildings consists of a long series of unit steps and it is non-procedural and data-intensive comparing with

structural analysis problem which is procedural and computation-intensive. Hence, there is a need to

investigate characteristics of the problem and to properly structure design information to effectively manage

it in the structural design process. This paper discusses modeling concepts to manage design information

efficiently and to support the design process effectively. TLG object modeling is the conceptual backbone of

the model of this study and provides a consistent modeling of structural components including not only

primitive members such as beams and columns but also composite ones such as floors, frames, and even

whole buildings.. An integrated structural design system for buildings has been developed based on these

modeling concepts and brief discussion about how the object model works throughout the whole structural

design process in the integrated structural design system is given at the end of this paper.

Keywords : Structural Design, Data Modeling, Computer-Aided Engineering

1. Introduction

In construction industry, information technology is

extending its range toward the integration of all the

activities and CIC (computer-integrated construction)

or construction CALS are among them. Design

information is at the heart of these digital integrations.

Digitalized design information is to CIC or CALS

what blueprint drawings are to the traditional

construction. Therefore, rational digitalization of

design information and computerization of design

process to generate digitalized design information are

prerequisite and essential to higher-level integration.

Structural design is one of the major design

activities for buildings. In the structural engineering, it

has been long continued to use computer for structural

analysis which is procedural and

computation-intensive. Recently, there have been

many researches for the computerization of design

problems. Design problems have their own

characteristics which are matters out of consideration

in the procedural and computation-intensive problems

which have been regarded as suitable ones for

computerization. Structural design consists of a long

series of unit processes and a large amount and various

kinds of data are generated and used throughout the

process. In many cases, they are generated, used and

changed non-procedurally and there are more

dependencies between them comparing with structural

analysis problems. It means that structural design has a

data-intensive characteristic. Therefore, rational data

management is a key to the successful development of

a structural design system.

In this research, an integrated structural design

system has been developed. It can assist engineers

throughout all the structural design process for

buildings from the initial planning to the final detail

design of members. This system involves numerous

data including not only the final design information

but also temporary data used in the process of design.

This paper discusses an object-oriented data model

which is a part of the system. The model serves both

the final design information and temporary data

required in each unit process. This paper presents only

the overall framework and some important concepts

because the whole model is so large to describe the

details in a paper

2. Concept of TLG Object Modeling

From the information management aspect, the

repetition of same type of structural components

should be managed efficiently without information

redundancy. This repetition results from the grouping

of structural components. The components can be

primitive members such as beams and columns, or

composite ones such as floors, frames, and column

lines. In a building, several girders would be grouped

Contact Author: Chee Kyeong Kim, professor, Dept. of

Architectural Engineering, Sunmoon Univ., Asan-si,

Chungnam, 336-708, Korea

Tel: +82-41-530-2321 Fax: +82-41-530-2839

e-mail: ckkim@sunmoon.ac.kr

1112 CTBUH 2004 October 10~13, Seoul, Korea

as “G1” and it means all the girders have same section

properties. It is an example for the primitive member

level grouping. In addition, it is possible to group

several floors into a floor type named “Typical Floor

Plan” if they have same shape and member lay-out. It

is an example for the composite component level

grouping.

To model efficiently these repetitions in structural

design information, TLG object modeling and

reference domain concept was devised. In TLG

modeling, a structural component is defined into three

objects. They are type object, local instance object, and

global instance object each defined in type, local, and

global domain respectively.

Figure 1 (a), (b), (c) show how a column can be

defined into three objects. They are SSColumnT type

object defined in type domain of figure 1 (a),

SSColumnL local instance object defined in local

domain of figure 1 (b), and SSColumnG global

instance object defined in global domain of figure 1 (c).

In the name of objects, the prefix SS means that it is a

structural component object. The suffix T, L, G means

type, local instance, and global instance, respectively.

The component name is located between the prefix and

suffix.

3. Type Objects defined in type domain

Some properties of a structural component can be

defined within the scope of the component itself

regardless of the whole scope and shared with many

other components of the same type. For example, the

sectional properties of the column, marked by ① in

figure 1 (c), can be described separately apart from

other parts of the building as shown in figure 1 (a), and

shared with any other 11 columns of the building given

in figure 1 (c) because they have same sectional

properties. In this case, it is an efficient way of

managing information to define the shared properties

only once and let all the components refer to it. A type

object is what consists of only this kind of attributes

and are referred to. A type domain means a space in

which the type objects can be described, and it is

inside of the component itself regardless of the whole

scope.

(A) Type Domain

• Domain Scope : column itself

• Domain where type objects are defined

• Column Object Name : SSColumnT

• Sample Attribute : sectional properties

500

(B) Local Domain

• Domain Scope : floor plan type

• Domain where local instance objects are defined

• Object Name : SSColumnL

• Sample Attribute : Location in the plan

Typical Floor

Roof Floor

Typical Floor

• Domain Scope : whole building

• Domain where global instance object are defined

• Object Name : SSColumnG

• Sample Attribute : Member Forces

Typical Floor

Figure 1. TLG Object Modeling

CTBUH 2004 October 10~13, Seoul, Korea 1113

Figure 1 (b) shows another example for type object.

It is a floor type object named “Typical Floor”, and is

referred to 3 times by floors from 1st to 3rd. In this

case, the detailed shape and member layout is

described only once as a type object and all the actual

floors of that type refer to it. Like this, type object can

be defined not only for primitive components but also

composite components such as floors, frames, and

even buildings. The type domain for floors may be a

horizontal plane in which each member is located

shown in figure 1 (b).

4. Local Instance Objects defined in Local domain

A type object of a composite component consists of

many primitive components or lower-level composite

components. The “Typical Floor” floor type object in

figure 1 (b) has 4 columns of type “C1” and a slab. In

this case, all 4 columns have same sectional properties,

but their location in the floor plan is different from

each other. It means that some attributes of a

component should be described in the scope of a

higher-level type object. A local instance object is what

has only this kind of attributes and is a part of

higher-level type object. A column local instance

object has the location information in a floor plan type

as one of its attributes. In general, a local instance

object refers to a type object to keep its type

information. All 4 column local instance objects,

which are assembled into “Typical Floor” floor type

object, refer to “C1” column type object. A local

domain means a space in which the attributes of local

instance objects can be described. A local domain for

local instance objects is the type domain for

higher-level type object. The type domain for “Typical

Floor” floor type object is the local domain for the

columns.

This relationship of lower-level local instance

objects and a higher-level type object may exist

between composite components recursively.

Considering the building in figure 1 (c) as a building

type object, it has 4 floor local instance objects. One of

them is “Roof Floor” type located on roof floor, and 3

+m_CompoT

SSBuildingL

(fro m SCFM )

+m_CompoL

SSBuildingG

(fro m S CFM )

Building

Object

1..*

SSBuildingT

(fro m S CFM )

+m_W holeObject

1..*

+m_Com poT

SSFloorL

(fro m S CFM )

+m_CompoL

SSFloorG

(fro m S CFM )

Floor

Object

0..*

1..*

SSFloorT

(fro m S CFM )

+m_W holeObject

0..*

+m_Com poT

SSBeamL

(fro m S CFM )

SSBeamG

(from S CFM )

+m_CompoL

0..*

1..*

SSBeamT

(fro m S CFM )

0..*

+m_CompoT

SSColumnL

(fro m S CFM )

+m_Com poL

SSColumnG

(from S CFM )

0..*

1..*

SSColumnT

(fro m S CFM )

0..*

Member

Object

+m_Com poT

SSWallL

(fro m S CFM )

+m_CompoL

SSW allG

(fro m S CFM )

0.. *

1..*

SSWallT

(fro m SCFM )

0..*

+m_CompoT

SSSlabL

(fro m S CFM )

+m_CompoL

SSSlabG

(from S CFM )

1..*

0.. *

SSSlabT

(f ro m SCF M)

Type Object

Local Instance

Object

Global Instance

Object

LEGEND

Cl a s s N ame

(f rom PackageName)

+Role

Multiplicity

Class

Aggregation

Association

Unidirectional

Association

Figure 2. TLG Modeling of a Building

1114 CTBUH 2004 October 10~13, Seoul, Korea

1..*

0..*

1..*

0..*

1..*

0..*

1..*

0.. *

1..*

0.. *

LEGEND

+Role

Cl a s s N ame

(f rom PackageName)

Multiplicity

Class

Aggregation

Association

Unidirectional

Association

of them are “Typical Floor” type from 1st floor to 3rd

each. Like this, the relationship of lower-level local

instance objects and a higher-level type object can be

formed recursively between more complex composite

components.

5. Global Instance Objects defined in Global domain

Lastly, some properties of structural components

should be defined in the whole building. Considering

the 3 columns at the left bottom corner between the 1st

floor and the 3rd, they are of same type and share the

“C1” column type object. In addition, they are at the

same location in the floor plan and share a local

instance object defined in “Typical Floor” floor type

object. However, the member forces of them are

different from each other, and they should be described

respectively. It means that some properties of a

component should be described in the scope of the

whole building. A global instance object is what has

only this kind of attributes. A column global instance

object has the member force information as one of its

attributes. The final structural design information

which consists of member layout with their section

properties can be represented only by type and local

instance objects without global instance objects. More

detailed will be given in the next section. However,

global instance objects hold a more important position

in the construction and maintenance stage because

each component should be treated individually

contrary to the design stage. In general, a global

instance object refers to a local instance object to keep

its additional information which is managed by local

instance object and type object. Twelve column global

instance objects are assembled into the whole building

as shown in figure 1 (c). Global instance objects are

same ones that exist in the real world. A global domain

means a space in which the attributes of global

instance objects can be described. It is exactly the real

world space and there is only one global domain

contrary to type domain or local domain.

6. Basic Approach to TLG Modeling for a Building

Figure 2 shows how a building object can be

modeled based on TLG object modeling concept. It is

not the exactly same one of this study because it is

simplified to explain the concept of TLG object

modeling and relationships between them. Aggregation

associations are used to represent that a higher-level

type object consists of many lower-level local instance

objects of various kinds of components, and

unidirectional associations are used to represent that

local instance objects and global instance objects refer

SSBuildingT_Sample

m_TID = 1

m_Name = SSBuildingT_Sample

m_DesignCode = ACI02

m_NumStories = 3

m_Location = Seattle, WA

m_Usage = Office

m_Analysis = ETABS

SSFloorT_Roof

m_TID = 2

m_Name = Roof Floor

m_W idth = 8000

m_Height = 6000

SSFloorT_Typical

m_TID = 3

m_Name = Typeical Floor

m_W idth = 8000

m_Height = 6000

SSColumnT_C1

m_TID = 4

m_Name = C1

m_W idth = 500

m_Depth = 500

m_Rebar = 8-#9

SSSlabT_S1

m_TID = 5

m_Name = S1

m_Thick = 150

m_Rebar = #9@200

+m_CompoT = 2

+m_W holeObject = 3

+m_CompoT = 3

+m_CompoT = 4

SSColumnL_LB

m_LID = 5

m_X = 0

m_Y = 0

+m_W holeObject = 2

+m_CompoT = 5

SSFloorL_Roof

m_LID = 4

m_Name = Roof Floor

m_FloorNum = 4

m_Height = 11000

+m_W holeObject = 1

SSColumnL_RB

m_LID = 6

m_X = 8000

m_Y = 0

SSFloorL_3rd

m_LID = 3

m_Name = 3rd Floor

m_FloorNum = 3

m_Height = 7500

SSColumnL_LT

m_LID = 7

m_X = 0

m_Y = 6000

SSFloorL_2nd

m_LID = 2

m_Name = 2nd Floor

m_FloorNum = 2

m_Height = 4000

SSColumnL_RT

m_LID = 8

m_X = 8000

m_Y = 6000

SSFloorL_1st

m_LID = 1

m_Name = 1st Floor

m_FloorNum = 1

m_Height = 0

+m_SlabLs

SSSlabL_ROOF1

m_LID = 10

m_X1 = 0

m_X2 = 8000

m_Y1 = 0

m_Y2 = 6000

SSSlabL_TYP1

m_LID = 9

m_X1 = 0

m_X2 = 8000

m_Y1 = 0

m_Y2 = 6000

Figure 3. Development Diagram of Type and Local Instance Object

CTBUH 2004 October 10~13, Seoul, Korea 1115

to a type object and a local instance object,

respectively. In this model, one building type object

(SSBuildingT) consists of floor local instance objects

(SSFloorL) located on each floor. This aggregation

association is realized by a m_WholeObject attribute

of part objects which is SSFloorL in this case. Each

floor local instance object has attributes which

describe their position within the building type object,

and are associated to floor type object (SSFloorT) by

m_CompoT attribute.

Each floor type object is composed of several

member local instance objects (SSBeamL,

SSColumnL, SSWallL, SSSlabL) located within the

corresponding floor type object. The association

relationship between floor type object and member

local instance objects is also realized by

m_WholeObject attribute. Each member local instance

object has attribute about their position in floor type

object, and is associated to the member type object

which contains the full detail by m_CompoT attribute.

Type objects and local instance objects of each level

including member, floor, and building, are enough to

manage the final design information of a whole

building. The final design information is mainly about

the layout of each member and their section properties.

A building type object is exactly the whole building

itself. Even though, global instance objects, which

have one-to-one correspondence to each real

component, are needed yet to manage the information

which should belong to each member respectively.

Member forces are a good example and they are

managed by global instance object in the structural

design process. In addition, it is sure that most of

information in after-design works such as construction

or maintenance should be managed by global instance

objects because these kinds of information should be

assigned respectively to each real component. Figure 3

shows the development diagram of type and local

instance objects for the sample building shown in

figure 1 (c).

Conclusively, in TLG modeling, a structural

component is defined into a type object in type domain,

a local instance object in local domain, and a global

instance object in global domain according to the

scope required for the description of attributes. This

modeling concept is applied not only the primitive

members but also the composite components such as

floors, flames, and even buildings recursively.

Defining recursively higher-level type objects which

consist of lower-level local instance objects, the

information redundancy resulted from the repetition of

same types of components can be managed efficiently

in a consistent manner.

7. Implementation and Applications

An integrated structural design system for buildings

has been developed based on the object model

described in this paper. The system serves all the

structural design process from initial planning to the

detail design of member sections. This chapter briefly

discusses how the object model works throughout the

whole structural design process in the system. The

focus of this chapter remains on the information

modeling aspects, rather than on system

implementation issues. The system provides all the

function required to write out a structural design report

which is one of the final products of structural design

work. The system consists of three parts: (i) integrated

database for data management, (ii) class libraries for

doing structural engineering works, and (iii) user

interface for interaction between the system and

engineers. The proposed object model was

implemented and included into class library part.

Figure 4 shows a series of user interfaces selected

from the system while it is doing the design of a RC

building. At the right side, it also describes the

generation of objects, the assignment of their attributes,

and the brief of information flow throughout all the

structural design process focused on building, floors,

and some kinds of member. It can be seen that even a

structural component is expressed by several kinds of

objects including type object, local instance object, and

global instance object for its final design information.

In addition, some kinds of process dependant objects

such as initial modeling objects, load objects, analysis

objects, and section design objects are generated and

used to perform the design process.

8. Conclusions

Digitalization of design information and

computerization of design process to generate

digitalized design information are critical for

higher-level integration in construction industry. A

rational data model of design information should be an

integral part of structural design systems and more

integrated construction systems because most

engineering activities in construction are executed

based on design information included in design

document such as drawings. This paper has presented

some modeling concepts and their application to

structural design of buildings. TLG object modeling

concept is introduced to formalize the grouping of

structural components in structural design of buildings.

Concept of core and extended object classification is

proposed in order to serve not only the final design

information but also process dependent temporary one.

Foundation and application object concept is used for

the extensibility and the reusability of the model.

Building object is designed so that it supports the

structural design process effectively and its

composition is described in detail.

An integrated structural design system for buildings

has been developed and the object model takes a part

of the system. The resulting model and system

demonstrates that the concepts discussed in this paper

fit well for the development of structural design

system. The successful development of the system also

shows that these concepts have the potential to be

1116 CTBUH 2004 October 10~13, Seoul, Korea

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