BIM 4D modeling for structural works scheduling: Case study of Gedung Pelayanan Arsip Universitas Negeri Yogyakarta

Abstract

Conventional construction scheduling relies on S-curves representing progress through cumulative cost-weighted percentages, concealing activity dependencies and producing inaccurate duration estimates. BIM 4D addresses this by linking a three-dimensional structural model to an explicit, activity-based schedule, making sequencing constraints visible before construction begins. This study develops a BIM 4D schedule for Gedung Pelayanan Arsip Universitas Negeri Yogyakarta, comparing its duration against the conventional S-curve and measuring how far both schedules deviate from the actual duration recorded on site. The research workflow integrates structural modeling and quantity take-off in Tekla Structures, activity duration calculation in Microsoft Excel using AHSP CK 2023 coefficients, the

standard in force when the project was executed in 2024, scheduling in Microsoft Project, and four- dimensional simulation in Autodesk Navisworks through TimeLiner. The structural model

comprises 541 cast units, a concrete volume of 1,148.50 m3, reinforcement weight of 143.74 tons, and formwork area of 5,406.98 m2, organized into 155 tasks across 37 pour phases and 14 zones. The BIM 4D method produced a structural duration of 127 working days, against 102 days from the conventional S-curve. The actual duration derived from the site weekly reports was about 132 working days. The BIM 4D estimate deviated by five days out of 132, a 3.8 percent error, whereas the S-curve underestimated it by 30 days out of 132, a 22.7 percent error. Formwork was identified as the rate-limiting resource of the concrete structure, a constraint the S-curve cannot reveal. BIM 4D yields a longer but more transparent and accurate schedule.