Ghang Lee

Parametric 3D modeling in building construction with examples from precast concrete

Buildings are complex products containing relatively large numbers of distinct parts that are collected in multiple assemblies for different design, analysis and production purposes. Modeling buildings in fully parametric 3D computer-aided design (CAD) systems offers numerous benefits in terms of productivity, the ability to rapidly generate design alternatives at different levels and elimination of errors that result from the disparity between different drawings in current practice. However, full realization of these benefits requires specialized functionality, including top-down modeling, objects with functional behavior, the ability to embed contextual design intent, automation of layout and detailing and appropriate management of similar objects. An effective system must provide such functionality while maintaining adequate response times. The requirements, features and performance have been examined as part of specification of a new 3D parametric CAD platform for the North American Precast Concrete Software Consortium (PCSC). They are described and discussed after a review of solid and parametric modeling, with examples from the domain of precast concrete construction.

Eliciting information for product modeling using process modeling

A product model is a formal and structured definition of product information. The most common procedure for defining a product data model is to first describe the business and/or engineering process in a formal process model, then to create a product data model based on the process model. However, there is a logical gap between process modeling and product modeling methods in the current ISO 10303 standard product modeling process. We propose a new formal approach, called Process to Product Modeling (PPM) in which process and product modeling can be logically linked. This paper focuses on the semantics and syntax for the Requirements Collection and Modeling (RCM) of PPM. The new RCM method aims to model heterogeneous business processes and their information flows. The major difference between the proposed method and traditional requirements collection methods is that it provides a theoretical linkage to integrate process models and a set of specific information items used in them. This theoretical linkage enables modelers to capture the contents, scope, granularity, and semantics of information used in activities, which are depicted in process models. A PPM method, called Georgia Tech Process to Product Modeling (GTPPM), has been developed and was deployed for the North American Precast Concrete Software Consortium; examples from this effort are presented. Experience to date indicates that the new RCM method and the GTPPM tool hold the potential to improve and expedite elicitation of information for product model development.

Usability principles and best practices for the user interface design of complex 3D architectural design and engineering tools

This study proposes usability principles for the user interfaces (UI) design of complex 3D parametric architectural design and engineering tools. Numerous usability principles have been developed for generic desktop or web applications. The authors tried to apply existing usability principles as guidelines for evaluating complex 3D design and engineering applications. However, the principles were too generic and high-level to be useful as design or evaluation guidelines. The authors, all with more than 10 or 30 years of experience with various CAD systems, selected and reviewed 10 state-of-the-art 3D parametric design and engineering applications and captured what they thought were best practices, as screenshots and videos. The collected best practices were reviewed through a series of discussion sessions. During the discussion sessions, UI design principles underlying the collected best practices were characterized in the line of existing UI principles. Based on the best practices and the derived common UI principles, a new set of refined and detailed UI principles were proposed for improving and evaluating 3D parametric engineering design tools in the future.

Strategies for Realizing the Benefits of 3D Integrated Modeling of Buildings for the AEC Industry

We explore the reasons why advanced information technology applications have not been adopted by the AEC industry. Within the industry, however, some sectors have made significant moves toward adoption of advanced IT. By examining these areas of success, we propose a framework for the incremental conversion of the AEC industry to fully incorporate advanced IT.

Avoiding design errors: a case study of redesigning an architectural studio

Abstract Most design problems have multiple interacting constraints and levels of analysis. Some designers are able to reduce errors by developing heuristics and rules of thumb that lighten the cognitive load that such design problems impose. In this study we explore these heuristics by studying three groups of experienced architects solving a one-hour design problem that involves issues of multiple levels of spatial organization. Only one group was able to solve the problem. A special coding scheme was developed to explore the use of several kinds of heuristics such as problem decomposition into design units, rules of thumb from domain knowledge and strategic design moves. The differences in heuristics were examined to identify possible causes for these errors.

Metrics for Quantifying the Similarities and Differences between IFC Files

Recently, several papers reported problems in data exchange using industry foundation classes (IFC). However, most comparisons were made based on a visual check, a manual count, and observation of properties that were selectively chosen. This study proposes a set of metrics for quantifying the similarities and differences between IFC files. The proposed metrics include the similarity rate, the matching rate, the globally unique identifier (GUID) preservation rate, the missing rate, and the addition rate. A long-term goal of this study is to develop a set of metrics for quantifying the information exchange rate between two IFC files. Automated identification of modified information versus newly generated information is an unsolved challenge. The proposed metrics were used in analyzing 88 IFC files generated from different systems to demonstrate the potential use of the proposed metrics.

Query Performance of the IFC Model Server Using an Object-Relational Database Approach and a Traditional Relational Database Approach

Most previous industry foundation classes (IFCs) servers were developed based on relational databases (RDBs), and many studies reported performance problems. This study developed the object-relational IFC (OR-IFC) server using the object-relational database (ORDB) approach to improve query performance by simplifying the mapping process of the inheritance structure and the aggregation concepts. In addition to the OR-IFC server, a RDB-based IFC server was also developed using mapping rules on the same database-management system as that on which the OR-IFC server was implemented to compare the performance of the ORDB- and RDB-based systems. The performance of the OR-IFC server and the RDB-based IFC server was evaluated using the Benchmark of Universal or Complex Kwery Ynterfaces benchmark method, and two test-case models with different sizes were used. The benchmark results clearly showed the query- performance improvement of the suggested OR approach. The OR-IFC server far outperformed the RDB-based server in every query related to object-oriented features such as inheritance, collection-type data, and referencing. DOI: 10.1061/(ASCE)CP.1943-5487.0000256.

Life-Cycle Cost Analysis on Glass Type of High-Rise Buildings for Increasing Energy Efficiency and Reducing CO 2 Emissions in Korea

As the heights of high-rise buildings increase, their building area and elevation area also increase, consequently increasing their yearly energy consumption. Energy efficiency has become an even more important issue, especially when glass is used for a buildings exterior. In this study, the life-cycle cost (LCC) of the exterior glass of high-rise buildings was analyzed from the perspective of energy efficiency and CO2 emissions. First, the LCC was analyzed according to changes in the selected types of glass. Reflective + Low-E (Type 1), double Low-E + Argon (Type 2), and triple Low-E + Argon (Type 3), which satisfy green building certification criteria and were used in the past for high-rise buildings in Korea, were selected as the exterior glass types. These types of exterior glass were applied to a case building and compared with the Low-E glass that was the existing glass type of a case building. The economic benefit of selected glasses for 40 years was greater in the order of Type 1, Type 3, and Type 2 compared to the existing glass. Second, these types of glass were applied to each orientation of the building. By changing the glass according to building orientation it is shown that in the east, west, and north, Type 1 was most economical, whereas Type 3 was most economical in the south. The results of this study will contribute to the improvement of energy efficiency, CO2 emissions reduction, and cost efficiency of future high-rise buildings. DOI: 10.1061/(ASCE)CO.1943-7862.0000502.

Quantification of construction waste prevented by BIM-based design validation: Case studies in South Korea

Waste generated in construction and demolition processes comprised around 50% of the solid waste in South Korea in 2013. Many cases show that design validation based on building information modeling (BIM) is an effective means to reduce the amount of construction waste since construction waste is mainly generated due to improper design and unexpected changes in the design and construction phases. However, the amount of construction waste that could be avoided by adopting BIM-based design validation has been unknown. This paper aims to estimate the amount of construction waste prevented by a BIM-based design validation process based on the amount of construction waste that might be generated due to design errors. Two project cases in South Korea were studied in this paper, with 381 and 136 design errors detected, respectively during the BIM-based design validation. Each design error was categorized according to its cause and the likelihood of detection before construction. The case studies show that BIM-based design validation could prevent 4.3-15.2% of construction waste that might have been generated without using BIM.

Concept-Based Method for Extracting Valid Subsets from an EXPRESS Schema

An EXPRESS schema is a data schema defined in EXPRESS, an international standard language for defining product data schemas. This technical paper proposes and formally defines a set of conditions for generating a minimum valid subset of an EXPRESS schema corresponding to a concept, where a concept is a general idea and a subset is a partial model of a data schema. We introduce a notion of “minimal set” to define the relationships between a subset and other subsets, and also between a subset and concepts. A minimal set is the smallest complete subset of a schema that corresponds to a concept. Using IFC, an international standard data model for the architecture, engineering, and construction industry, the proposed conditions have been implemented in a software application developed for extracting subsets from the IFC schema matching the concepts. A number of examples are demonstrated. DOI: 10.1061/ ASCE 0887-3801 2009 23:2 128 CE Database subject headings: Computation; Computer software; Data processing; Standardization.