Abstract
Remodeling underground structures requires careful construction planning, including consideration of costs and scheduling. Therefore, this study aims to analyze and compare the effects of four methods for vertically extending the underground spaces of an existing building under scheduling and cost constraints. The study considers the following extension methods: (1) bottom-up method, (2) normal top-down method after demolition, (3) normal top-down method in parallel with demolition, and (4) top-down method using double beams in parallel with demolition. Twelve illustrative examples are presented to investigate the constructability of these methods in terms of construction scheduling and costs. The construction durations and costs of each example is calculated and compared. We also analyze the structural stability of the examples using MIDAS Gen 2017. We conclude that the top-down method using double beams is the most efficient method in terms of costs and scheduling. The results and analysis process can help practitioners to select appropriate methods to expand underground spaces without demolishing entire existing buildings and efficiently manage costs and schedules. In future studies, these extension methods should be applied to real-world projects in various countries to validate and verify their actual effects on construction costs and scheduling.
Highlights
This study aims to analyze demolition work, retaining walls,construction pile work, percussion drills (PRDs), temand compareand thebackfill constructability, including costs and rotary scheduling, of the four porary underground post work, strut and excavation top-down excavation work, foundation work, vertical extension methodswork, in existing structures considering the amount of structural frame construction, finish work, inspection, and miscellaneous work
We analyzed the constructability of the four methods for vertically extending existing underground spaces of buildings, namely the bottom-up method, normal top-down method after demolition, normal top-down method in parallel with demolition, and top-down method using double beams in parallel with demolition
The top-down methods were more effective than the bottom-up method from both the cost and scheduling perspectives
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Urban area populations are growing rapidly worldwide and the availability of space in congested urban areas is decreasing [1]. Underground spaces beneath buildings are increasingly utilized [2,3,4,5]. To make use of such spaces, stable structures are often dismantled and reconstructed in the same location. Demolition and reconstruction of buildings incur enormous costs as well as leading to other problems such as environmental pollution and complaints [6]. Remodeling underground structures has more significant impacts in terms of the environment, costs, and scheduling than remodeling superstructures [5,7]
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