Chaeyeon Lim

A Dynamic Erection Simulation Model of Column-Beam Structures Using Composite Precast Concrete Components

An innovative column-beam structure called Green Frame (GF), which uses composite precast concrete (CPC) components, was developed to enhance constructability, economy, and environmental friendliness compared with the existing structural system. Unlike conventional precast concrete (PC), the CPC components of GF are connected using shaped steels, which results in a different working method and erection time. In addition, the components are produced within the crane working radius where only a limited quantity is supplied, which impacts the erection time. In turn, the erection time generates a dynamic problem that influences the total amount of production and time. According to case studies on the application of GF, erection time is more critical than production. Thus, information on the erection process of CPC components and the working time of each task should be analyzed to solve the dynamic scheduling issue between production and erection. The objective of this paper is to develop a dynamic erection simulation (DES) model of column-beam structures using CPC components produced within the working radius of cranes. The DES model can easily and quickly establish an erection schedule for GF in response to changes in the on-site production and erection conditions.

Economic Analysis of Korea Green Building Certification System in the Capital Area Using House-Values Index

Abstract Since 1980, there have been widespread efforts by international organizations, governments, and research centers to achieve sustainable development. In Korea, green building certification has been developed and adopted for various types of buildings. However, although research has been conducted regarding the economic benefits of the Korean green building certification system, no research efforts have compared the average house-values between green building certified and non-certified buildings. In addition, there is a lack of research concerning the impact of public transit on the average house-values in certified green buildings. The objective of this study is to investigate the economic benefits of green certified buildings using the average house-values index and to identify how proximity to public transit affects building values. According to the findings, house-values are higher for green certified buildings than for non-certified buildings. Furthermore, house values increase with proximity to bus stops. These results reflect the potential economic gain from a utilization of the Korean green building certification system (K-GBCS). In addition, by illustrating the economic benefits of the system, this study could encourage major stakeholders to use the K-GBCS.

Optimum Tower Crane Selection and Supporting Design Management

To optimize tower crane selection and supporting design, lifting requirements (as well as stability) should be examined, followed by a review of economic feasibility. However, construction engineers establish plans based on data provided by equipment suppliers since there are no tools with which to thoroughly examine a support designs suitability for various crane types, and such plans lack the necessary supporting data. In such cases it is impossible to optimize a tower crane selection to satisfy lifting requirements in terms of cost, and to perform lateral support and foundation design. Thus, this study is intended to develop an optimum tower crane selection and supporting design management method based on stability. All cases that are capable of generating an optimization of approximately 3,000 ˜ 15,000 times are calculated to identify the candidate cranes with minimized cost, which are examined. The optimization method developed in the study is expected to support engineers in determining the optimum lifting equipment management.

Cost Analysis of the Structural Work of Green Frame

The adoption of Green Frame is expected to provide economic benefits, since construction costs are reduced by the in-situ production of precast concrete column and beam. The cost reduction can ultimately be realized by saving transportation costs and the overhead and profit of PC plants. The cost structure of Green Frame, which is built up using composite precast concrete members, is similar to that of a bearing-wall structure, but the difference in construction process has resulted in some cost differences for a few items. In particular, production and installation is the principal work involved in Green Frame made by precast concrete members, while form and concrete work is the principal work for a bearing-wall structure. As such, the rental time and fee for a tower crane should be compared through time analysis. To verify reliability, this study focused on developed residential projects to estimate the construction costs. Through this analysis, it was found that the costs of Green Frame were 1.57% lower than the costs of bearing-wall structure. The results of this study will help in the development of a management plan for the structural work of Green Frame.

Health performance and cost management model for sustainable healthy buildings

The construction industry is a flourishing business. Demand for ‘sustainable healthy buildings’ is rapidly increasing with the growing population. As the population increases, problems associated with health impacts of a building would also increase. Addressing the health problems of buildings could require raising of construction cost. In order to maintain a reasonable cost, a construction project might possibly have to compromise health performance and cost, which thus illustrates the major dilemmas being faced in the construction industry. Proper building health management is obligatory to reduce and control health problems and to maintain comfort levels throughout a building’s life cycle. To achieve this, a health performance evaluation model has been proposed to measure the level of health performance throughout a building’s life cycle. However, detail solutions of cost issues are not within scope of this paper. The objective of this paper is to propose a health performance and cost management model to achieve satisfactory health performance level within the project budget. The main significance of this model is to establish a decision-making process for decision-makers to improve and identify problems that could affect the health performance of a building throughout a building’s life cycle, thus allowing stakeholders to resolve shortcomings and to apply advanced solutions for building upgrade.

Lifecycle Health Assessment Model for Sustainable Healthy Buildings

A system to analyze, assess and manage the health performance of resources and spaces throughout the project lifecycle shall be established to ensure sustainable healthy buildings. Decisions made in the planning, design, construction, and operation and management (OM the Lifecycle Health-performance Tree (LHT) module, which analyzes the hierarchy of spatial and health impact factors; the Health Performance Evaluation (HPE) Module; and the Lifecycle Health Management Module, which analyzes and manages changes in health performances throughout the lifecycle. The model helps ensure sustainable health performances of buildings.

A Health Performance and Cost Optimization Model for Sustainable Healthy Buildings

To construct a sustainable and healthy building, it is necessary to build a system capable of efficiently analyzing, assessing and managing health performance data over the life cycle of a building. To fulfill such needs, health-friendly resources database, life cycle health-performance tree, health performance evaluation and health management concepts were suggested. Such studies focused on health performance. Selecting building materials based only on their health performance while ignoring cost is likely to lead to not only rapid construction cost increases, but also higher maintenance costs. For cost-benefit management, the health performance and cost management model was proposed. However, while the model can be used in decision-making, it is unable to suggest an optimization solution. To supplement this need, this study proposes a health performance and cost optimization model for sustainable healthy buildings. The model proposed here is composed of simulation and optimization modules for health performance and cost using the concepts mentioned above.

Development of a steel-guide connection method for composite precast concrete components

AbstractGreen Frame is a column-beam structure formed by connecting a composite precast concrete beam with a steel connection on the column side. Similar to steel frame construction, the green columns cover 3 stories per unit, and generate vertical and horizontal eccentricities due to construction errors and the gravitational loads of beams. Such eccentricities make it difficult to install the upper floor beams and adjacent frames. This problem not only results in decreased productivity, but also in time delays and cost overrun. The objective of this study is to develop a new steelguide connection method for composite precast concrete (CPC) components after analysing the erection process and structural mechanism to resolve eccentricity issues. The connection mechanism developed in this study resolves these eccentricities and promotes efficient, accurate, and safe construction.

Automatic Rebar Estimation Algorithms for Integrated Project Delivery

Integrated project delivery is advantageous in that it can reflect the constructor′s expertise at the design phase. Furthermore, integrated project delivery allows project stockholders to promptly evaluate the financial performance of design decisions. However, there are many problems among existing quantity estimation processes, including human error, loss of information during data exchange and import-export, and time delays. These problems are major obstructions to the application of integrated project delivery. In particular, when it comes to rebar in structural works, errors generated during the drafting process of structural design information have a direct impact on estimation and construction. Such errors can be resolved by employing automatic quantity estimation software that uses the structural design information. In this regard, the present study proposes an automatic rebar estimation algorithm for use in integrated project delivery, the purpose of which is to further develop the software necessary for integrated project delivery. Continued development of additional algorithms for other types of resources as well as software capable of integrating these tools will lead to excellent decision-making support tools for project stockholders, including architectural designers.

Embodied Energy and CO2 Emission Reduction of a Column-Beam Structure with Enhanced Composite Precast Concrete Members

Abstrct Green Frame is a column-beam system that uses composite precast concrete members. Previous studies have proven this system to be not only structurally safe, constructible, and economically feasible, but also environmentally friendly. However, the column and beam of the frame need to be improved further in terms of structural performance in order to reduce the CO2 emissions. To this end, a more enhanced structural system than the existing Green Frame has been developed. The aim of this paper is to analyze the embodied energy and CO2 reduction effect of a column-beam structure with enhanced CPC members. An apartment building project was selected as a case study, and the CO2 reduction effect was compared between the existing and enhanced Green Frame. It was found that the improved system would result in a 3% reduction in CO2 compared with the existing one.