A dynamic simulation model for economic feasibility of apartment development projects

Many factors influence the success of apartment development projects, but it is difficult to quantitatively measure them. In terms of risk control, the five most direct influence factors are sales ratio, unit sale price, financial cost, land cost, and construction cost. These factors will vary during the project, from planning to land purchase to design to sale to construction, and the levels of these factors will also affect project performance. Therefore, it is necessary to dynamically forecast, control and monitor, and manage these factors in order to successfully implement apartment development projects. This study develops a dynamic simulation model to analyze the economic feasibility of apartment development projects. It draws a causal loop diagram of the aforementioned influence factors, develops a simulation model using system dynamics, and verifies the model with a case study of a 1,794-unit apartment development project. Using this simulation model, it is possible to quickly and easily simulate the economic effects of the risk factors that change throughout the project, analyze its economic feasibility, and develop a plan to reduce economic losses, if necessary. The simulation model can also identify the optimal conditions for project feasibility and develop a risk-control model for apartment development projects

An experimental study for quality assurance of free-form concrete panels produced by CNC machine

Various studies have been conducted to construct free-form buildings, but it still takes a lot of labor, cost, and time to assure the accuracy of designed shapes. In particular, molds for the production of free-form concrete panels (FCPs) are putting enormous burdens on productivity and cost. To produce FCPs economically, a computerized numeric control (CNC) machine that produces phase change material (PCM) molds for persistent use was developed in this study. The technology using CNC machine can produce precisely free-form molds and panels in a short time compared to the manual method. However, in order to commercialize this technology, it is necessary to verify the shape error of the FCPs. Therefore, the purpose of this paper is an experimental study for securing FCP quality produced by a CNC machine. The results of this study will be used to mass-produce uniform quality of FCPs without depending on the skill and workmanship of the labor

Time reduction effect of the enhanced TACT method for high-rise residential buildings

The finish work on high-rise residential buildings is performed simultaneously with mechanical and electrical construction work, which results in frequent work interference and delay. This significantly hinders efficient schedule management. Critical Path Method (CPM) is inefficient when applied to high-rise residential building projects in which work is repeatedly carried out for each floor. Line-of-Balance (LOB) is widely used for its effectiveness in managing repetitive work. LOB was developed into TACT and eTACT (enhanced-TACT) to combine heterogeneous works con­tinuously. In particular, the eTACT schedule management method has an advantage in that it is capable of systemati­cally connecting detailed construction, mechanical and electrical construction projects using a work planning template. This study evaluates the time reduction effect of the eTACT method for a high-rise residential building. A comparative analysis of data on 102 cases of non-applied projects and 44 cases of projects using the eTACT method over a period of 10 years is presented to verify its effectiveness. The result shows that finish work time was reduced by 25% or about 53 days on average. First published online: 18 Dec 201

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

Green 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 steel-guide 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. First published online: 01 Jul 201

Time reduction effects of steel connected precast concrete components for heavily loaded long-span buildings

The characteristics of large logistics buildings are their long spans and the ability to take heavy loads. Usually, PC components are used for their frames to ensure quick construction. However, the erection of most pin jointed PC structures increases the time and the cost incurred for ensuring structural stability and construction safety. To solve this problem, “smart” frames have been developed, which have tapered steel joints at both ends of the PC components. A smart frame with the moment frame concept not only assures structural stability and construction safety, but it also simplifies and quickens the erection because of its tapered joint detail. The purpose of this study is to compare the erection time and cost effects of the steel connected PC components for heavily loaded long-span logistics buildings with the existing PC frames. For this study, we selected a logistics building constructed with PC components and redesigned it as the smart frame, and the erection simulations were performed. We analyzed the time reduction effects of the smart frame. Our results confirmed that the use of the smart frame reduced the erection time and cost practically. Our investigations will help develop the erection simulation algorithms for smart frames

A solution of subordinate vertices for quality connections of external free-form concrete panels

3D-designs of free-form buildings are developed using a computer due to difficulty of shape implementation. When producing free-form concrete panel (FCP) using materials such as GFRC (glass fiber reinforced concrete), engineers or manufacturers should precisely calculate the offset value or geometry of each member at the junction point of three or more FCPs before it is constructed. However, it is difficult to calculate offset geometry easily and quickly, and no research has been conducted on this topic. Therefore, the objective of this paper is to develop a solution of subordinate vertices for quality connections of external free-form concrete panels. The developed mathematical solutions practically support the production of FCPs with precise installation to ensure aesthetic quality of the building. This paper academically contributes to the automatic creation of joint details of FCPs implemented by BIM

Evaluation of CO2 emission reduction effect using in-situ production of precast concrete components

Precast concrete (PC) construction method is typically preferred due to its reduced construction time, quality assurance, and cost effectiveness. Experimental studies have proven that in-situ production of PC components ensures equivalent or enhanced quality with substantial cost reductions compared to those of in-plant production, under the same production conditions. The construction method may also be environment friendly due to its relatively low CO2 emissions. However, it is necessary to examine the degree of this method’s effectiveness via experimental studies. The purpose of this study is to evaluate the CO2 emission reduction effect of in-situ production of PC components. Using a case project, the CO2 emission is estimated and compared for the operations between in-situ and in-plant production. The CO2 emission of in-situ produced PC components reduced by 14.3% or more when compared to the in-plant production. This shows that in-situ production of PC components can greatly reduce CO2 emissions, while maintaining its cost effectiveness and quality assurance. Furthermore, this study contributes in changing the negative perception of in-situ production of PC components and in the development of algorithms that scientifically analyze the CO2 emission reduction effect of in-situ production of PC components

Unmanned Aerial Vehicles (UAV) Integration with Digital Technologies toward Construction 4.0: A Systematic Literature Review

Unmanned Aerial Vehicles (UAVs) have been employed in the construction industry in the last decade for various purposes such as progress monitoring and building inspection. Recently, there has been a rising trend of employing UAVs with other digital technologies (DTs), such as Building Information Modeling and Extended Reality. The integration of these technologies encourages automation and digitization toward better project performance. However, little is known about the implementation of UAVs in conjunction with other DTs. Therefore, this study performs a systematic literature review to determine application areas and technology trends regarding UAVs’ integration with other DTs. The search yielded 287 articles, of which 36 satisfied the established inclusion criteria and formed the foundation of this systematic review. Seven application areas of UAV integration with other DTs were identified: progress monitoring, historic building conservation, information management, construction safety, construction education, structural and infrastructure inspection, and transportation. This study also revealed UAV technology trends encouraging automation and digitization: automated progress monitoring, automated UAV inspection planning, real-time video streaming, and parametric model development of historicbuildings. This study is expected to be a starting point of future in-depth research by providing a general understanding of the current applications of UAVs integration with other DTs

A Holistic Review of Building Energy Efficiency and Reduction Based on Big Data

The construction industry is recognized as a major cause of environmental pollution, and it is important to quantify and evaluate building energy. As interest in big data has increased over the past 20 years, research using big data is active. However, the links and contents of much literature have not been summarized, and systematic literature studies are insufficient. The objective of this study was a holistic review of building energy efficiency/reduction based on big data. This review study used a holistic analysis approach method framework. As a result of the analysis, China, the Republic of Korea, and the USA had the most published papers, and the simulation and optimization area occupied the highest percentage with 33.33%. Most of the researched literature was papers after 2015, and it was analyzed because many countries introduced environmental policies after the 2015 UN Conference on Climate Change. This study can be helpful in understanding the current research progress to understand the latest trends and to set the direction for further research related to big data

The effectiveness of Korea green building certification system in terms of sustainable development

행사명 : International Symposium on Sustainable Healthy Building