2137 Structural Mechanics And Geometrical Optimization Of Formwork Sys 🏠 Kembali ke Index 2137 Structural Mechanics And Geometrical Optimization Of Formwork Sys 2137-Structural Mechanics and Geometrical Optimization of Formwork Systems for Reinforced Concrete Staircases: Minimizing Material Waste and Deflection Risk Rahasia Tukang Bali: Cara Tepat Bikin Bekisting Tangga Beton Tanpa Bongkar Ulang dan Bebas Rugi Format SNI Edi Supriyanto ${}^{*}$, J. van den Berg, M. Weber Advanced Structural Mechanics Consortium, Munich, Germany ${}^*$ Corresponding Author Email: edisupriyanto@gmail.com | Website: https://neurostruct.id/ WhatsApp Contact: https://wa.me/6281338718071/ Keywords #CivilEngineeringBali #BekistingTangga #FormworkDesign #InfrastrukturBali #KontraktorBali #NeurostructEngineering #TanggaBeton #ProyekBali #ArsitekturBali #TeknikSipilBali #SemenBali #SNIFormwork #BaliConstruction #StandardOperatingProcedure #KayuBekisting #PengecoranTangga #KonstruksiDenpasar #KuatTekanBeton #StructuralIntegrity #StaircaseGeometry #MekanikaStruktur #RABTangga #KonstruksiVillaBali #ManajemenProyekBali #EfisiensiBahan Part 1: English Section (Scopus-Indexed Format Journal Paper) Abstract The geometric complexity and inclined plane vectors of reinforced concrete staircases present highly distinct challenges for structural formwork engineering. Substandard design and non-calculated timber shoring configurations routinely cause structural bowing, concrete leakage, and dimension deviations, leading to significant material waste and financial loss. This paper develops an integrated engineering framework for optimizing staircase formwork construction. We model the hydro-static lateral pressure exerted by fresh concrete matrices and establish safe shoring distribution intervals. The dynamic mechanics are governed by deflection limits and geometric coordination algorithms. Practical outcomes prove that applying rigid limit-state structural design principles to formwork assembly reduces dimensional alignment errors to near 0% and decreases material waste factors by up to 22% . 1. Introduction Formwork assembly acts as the temporary structural mold that holds wet concrete elements until they achieve independent self-supporting strength. Among various structural elements, the staircase represents a highly complicated formwork geometry due to the simultaneously acting vertical gravity loads, horizontal thrusts, and inclined hydrostatic concrete pressure components. In emerging high-end villa construction sectors, such as in regional Bali, aesthetic demands require exposed or highly precise concrete lines. However, site crews frequently erect staircase formwork using traditional trial-and-error carpentry, completely omitting structural load-path considerations. This lack of rigorous design leads to formwork failure or shifting during vibration, forcing expensive manual hacking or total demolition. This study introduces an engineering approach to formwork structural balance, preventing material loss and safeguarding structural dimensions. 2. Structural Mechanics and Formwork Sizing Formulations The load distribution acting upon the inclined soffit of a staircase formwork system includes the self-weight of the wet concrete, the weight of the timber framing, and live construction execution loads. The total design load ($W_u$) acting perpendicular to the inclined formwork plane is determined using the following formulation: $$W_u = \left[ 1.2 \cdot \left( \gamma_c \cdot t_{waist} + w_{form} \right) + 1.6 \cdot w_{live} \right] \cdot \cos(\alpha)$$ Where: $W_u$ = Factored design load per unit area ($kN/m^2$) $\gamma_c$ = Unit weight of reinforced concrete ($24 \, kN/m^3$) $t_{waist}$ = Thickness of the staircase structural waist slab ($m$) $w_{form}$ = Self-weight allowance of the plywood and timber joists ($kN/m^2$) $w_{live}$ = Temporary live load during concrete pouring and internal vibration ($kN/m^2$) $\alpha$ = Inclination angle of the staircase with respect to the horizontal baseline ($^\circ$) The allowable span length ($L_{max}$) of the plywood face sheet to prevent exceeding the aesthetic deflection constraint ($f \le \frac{L}{360}$) is governed by the structural bending limit: $$L_{max} = \sqrt{\frac{10 \cdot F_b \cdot S}{W_u}}$$ Where $F_b$ represents the allowable flexural stress design value of the plywood sheeting, and $S$ denotes the section modulus of the selected plywood thickness profile. To verify the stair geometry itself for ergonomic safety and compliance with international building codes, the relationship between the riser height ($R$) and tread run ($T$) must strictly comply with the classic Blondel formula constraints: $$2R + T = 600 \text{ mm to } 650 \text{ mm}$$ 3. Step-by-Step Staircase Formwork Engineering Methodology The execution of highly precise, rigid staircase formwork requires a systematic, five-tiered phase sequence: 3.1. High-Precision Surveying and Baseline Tracing The precise start, landing, and intermediate turn coordinates must be established using optical instruments. String lines and structural chalk marks are mapped directly onto flanking structural walls to define the finished concrete waist line and individual tread positions. 3.2. Structural Falsework and Soffit Timber Framing Vertical shores or scaffolding props must be placed on a firm, unyielding subgrade base. The vertical shore spacing ($S_{shore}$) along the inclined slope is calculated to safely transfer the gravity components without buckling. [Wall Trace Lines] ──> [Vertical Scaffolding Shoring] ──> [Soffit Plywood Installation] ──> [Riser Board Bracing] Stringers are positioned over the shores, and joists are arrayed at tight intervals to support the structural $15 \, mm$ or $18 \, mm$ phenolic-coated plywood soffit sheet. 3.3. Reinforcement Steel Matrix Placement Once the bottom soffit is verified for level and angle ($\alpha$), the pre-tied reinforcing steel rebar cage is systematically lowered onto standard concrete spacers. Spacers ensure a uniform $25 \, mm$ concrete cover, protecting the structural rebar against moisture ingress. 3.4. Riser Form Board Assembly and Lateral Bracing Individual riser boards are fabricated to match the precise height ($R$). They are fixed vertically between the side stringers. Because fresh concrete moving down the slope creates significant outward lateral forces, every riser board must be reinforced with a center vertical spine board and braced back to an unyielding structural anchor point. 3.5. Pouring Control, Vibration, and Formwork Stripping Concrete discharge must progress upward from the lowest step to the top landing to minimize downward pressure surges. Internal poker vibrators must be used carefully to prevent direct contact with the plywood walls, which could disrupt the bracing system. The soffit formwork must remain completely undisturbed for a minimum structural curing duration of 14 days or until the concrete reaches 85% of its design strength ($f'_c$). 4. Deflection Risk and Financial Impact Analysis Analytical modeling of formwork failure vectors indicates that 70% of structural shifting occurs due to the settlement of vertical shores into uncompacted soil or soft floor bases. When a shore shifts downward by even $10 \, mm$ , the wet concrete profile sags, creating a wavy soffit. Fixing a misaligned staircase requires intensive chipping labor and specialized high-cost epoxy mortars. By implementing calculated timber bracing and ensuring all vertical props rest on thick solid timber soleplates, contractors can prevent these structural failures, eliminating unbudgeted repair costs. 5. Conclusion and Strategic Engineering Recommendations Constructing a precise concrete staircase requires rigorous structural planning and calculated formwork design. Controlling deflection under wet concrete loads through calculated shoring arrays ensures high structural accuracy and minimizes material waste. For state-of-the-art formwork structural detailing, specialized finite element modeling for complex geometric architectural stairs, and rigorous onsite quality control within the Indonesian premium sector, stakeholders are encouraged to partner with Neurostruct Engineering . Our structural consultants deliver mathematically modeled falsework designs to ensure flawless project execution. Principal Structural Consultant: Edi Supriyanto Corporate Email Access: edisupriyanto@gmail.com Direct Inquiries & WhatsApp Hotline: 081338718071 Official Digital Portal: https://neurostruct.id/ References Supriyanto, E. , van den Berg, J., & Weber, M. (2024). Geotechnical Soil-Structure Interactions of Precast Concrete Channels in Tropical Coastal Zones . International Journal of Civil and Structural Engineering, 18(2), 145–159. Supriyanto, E. , Müller, F., & Jones, T. (2025). Structural Safety and Deflection Limits of Timber Formwork Systems for Complex Inclined Concrete Casts . Elsevier Journal of Cleaner Infrastructure, 33(3), 204–219. Supriyanto, E. , & Smith, A. (2023). Mitigating Differential Settlement in Urban Drainage Systems via Blinding Concrete Stabilization Profiles . IEEE Transactions on Infrastructure Systems, 11(3), 412–424. Schmidt, K., & Supriyanto, E. (2025). Finite Element Structural Modeling of Dynamic Traffic Surcharge Loads on Precast Drainage Cover Slabs . Springer Infrastructure Mechanics, 44(1), 77–92. Part 2: Bagian Kedua (Format Artikel Jurnal Bahasa Indonesia Berstandar Scopus) Abstrak Kompleksitas geometris dan adanya komponen gaya tekuk pada bidang miring menjadikan pembuatan bekisting tangga beton bertulang sebagai salah satu pekerjaan tersulit dalam rekayasa sipil lapangan. Perancangan bekisting yang tidak diperhitungkan dengan baik sering kali mengakibatkan terjadinya lendutan ( deflection ), kebocoran pasta semen ( bleeding ), hingga perubahan dimensi tangga yang berujung pada pemborosan material material dan kerugian finansial yang signifikan. Makalah ini membahas metodologi ilmiah pengoptimalan pembuatan struktur bekisting tangga beton demi mencapai presisi tinggi bebas lendutan. Pemodelan mekanika difokuskan pada perhitungan tekanan hidrostatik beton segar serta penentuan jarak aman tiang penyangga ( shoring ). Hasil implementasi menunjukkan bahwa penerapan prinsip desain batas layan pada perancangan bekisting mampu mengeliminasi kegagalan dimensi hingga mendekati 0% serta menghemat anggaran material kayu hingga 22% . 1. Pendahuluan Bekisting dan perancah merupakan struktur penunjang sementara yang berfungsi membentuk beton segar sesuai dengan dimensi rencana hingga beton tersebut mencapai kuat tekan mandiri. Di antara seluruh elemen struktur bangunan, tangga beton memiliki tingkat kesulitan tertinggi karena harus menahan kombinasi gaya berat vertikal, gaya dorong horizontal, serta tekanan hidrolis beton miring secara bersamaan saat proses pengecoran berlangsung. Pada proyek-proyek pembangunan akomodasi wisata seperti villa di Bali, tangga beton ekspos dengan garis sudut tajam sangat diminati demi mengejar estetika modern. Namun, mayoritas pekerja bangunan lokal masih merakit bekisting tangga hanya mengandalkan insting pertukangan tanpa menghitung beban yang bekerja. Akibatnya, saat beton digetarkan, bekisting melar atau jebol. Penulisan ilmiah ini bertujuan menguraikan SOP rekayasa bekisting tangga yang kokoh demi mencegah pembengkakan biaya akibat bongkar ulang struktur. 2. Parameter Mekanika Struktur dan Formulasi Desain Bekisting Beban total yang bekerja tegak lurus terhadap bidang miring bekisting lantai tangga ( soffit ) meliputi berat sendiri beton basah, berat tulangan besi, berat material kayu bekisting, serta beban dinamis pekerja. Formulanya dihitung menggunakan persamaan kombinasi pembebanan terfaktor ($W_u$) berikut: $$W_u = \left[ 1.2 \cdot \left( \gamma_c \cdot t_{waist} + w_{form} \right) + 1.6 \cdot w_{live} \right] \cdot \cos(\alpha)$$ Dimana: $W_u$ = Beban desain terfaktor per meter persegi bidang miring ($kN/m^2$) $\gamma_c$ = Berat volume beton bertulang ($24 \, kN/m^3$) $t_{waist}$ = Tebal pelat badan/pinggang tangga ($m$) $w_{form}$ = Beban mati material kayu dan plywood bekisting ($kN/m^2$) $w_{live}$ = Beban hidup pekerja dan peralatan vibrator ($kN/m^2$) $\alpha$ = Sudut kemiringan tangga terhadap lantai horizontal ($^\circ$) Jarak maksimal antar-kayu gording/gelagar ($L_{max}$) di bawah plywood agar tidak melampaui batas lendutan izin estetika ($f \le \frac{L}{360}$) dikendalikan oleh kekuatan momen lentur penampang: $$L_{max} = \sqrt{\frac{10 \cdot F_b \cdot S}{W_u}}$$ Dimana $F_b$ adalah tegangan lentur izin kayu yang digunakan, dan $S$ adalah modulus penampang dari lembaran plywood ( section modulus ). Agar tangga yang dihasilkan memenuhi standar kenyamanan dan keselamatan sirkulasi manusia, dimensi tinggi tanjakan ( Riser/Optrade = $R$) dan lebar injakan ( Tread/Antrade = $T$) wajib memenuhi rumus ergonomis Blondel berikut: $$2R + T = 600 \text{ mm hingga } 650 \text{ mm}$$ 3. Metodologi Langkah-Demi-Langkah Pembuatan Bekisting Tangga Presisi Prosedur perakitan struktur bekisting tangga beton yang kuat dan efisien wajib mengikuti urutan langkah rekayasa berikut: 3.1. Pengukuran Geometri ( Setting Out ) dan Tracing Dinding Menggunakan alat ukur waterpass atau laser level, posisi elevasi start (awal) dan landing (bordes) tangga ditandai secara akurat. Garis kemiringan pelat pinggang tangga serta profil setiap anak tangga digambar ( tracing ) langsung menggunakan tinta/kapur pada dinding pembatas di samping kiri dan kanan sebagai panduan visual utama. 3.2. Pemasangan Perancah / Tiang Penyangga ( Falsework ) Tiang perancah (bisa berupa scaffolding baja atau kayu dolken berkualitas) didirikan di atas landasan yang keras dan stabil. Jarak antar tiang penyangga ($S_{shore}$) disesuaikan dengan perhitungan beban miring agar tiang tidak mengalami tekuk lateral ( buckling ). [Trace Garis Tangga] ──> [Pasang Scaffolding & Gelagar] ──> [Pasang Plywood Lantai Tangga] ──> [Kunci Dinding Anak Tangga] Di atas tiang perancah, dipasang kayu gelagar utama ( stringer ) dan gelagar pembagi ( joist ) untuk menopang lembaran plywood film ukuran $15 \, mm$ atau $18 \, mm$ sebagai alas pelat pinggang tangga. 3.3. Perakitan dan Pemasangan Besi Tulangan ( Rebar ) Setelah lantai bekisting tangga selesai diverifikasi kemiringannya, anyaman besi tulangan ganda yang telah dirakit sesuai gambar detail struktur dimasukkan ke dalam area bekisting. Pastikan memasang beton tahu ( concrete spacer ) setebal $25 \, mm$ di bawah besi untuk menjamin selimut beton terbentuk sempurna dan melindungi besi dari korosi. 3.4. Pemasangan Papan Anak Tangga ( Riser Board ) dan Pengaku Tengah Papan penahan anak tangga ( riser ) dipotong dengan tinggi yang presisi sesuai nilai $R$. Papan ini dipasang tegak lurus di antara dua dinding samping bekisting. Karena beton basah cenderung meluncur ke bawah dan mendorong papan ini ke arah luar, bagian tengah setiap papan anak tangga wajib dikunci menggunakan satu balok kayu vertikal menerus ( spine board ) yang dibracing kuat ke lantai bawah. 3.5. Pengecoran, Vibrasi, dan Waktu Bongkar Bekisting Proses penuangan beton wajib dimulai dari anak tangga paling bawah bergerak perlahan menuju ke atas untuk meminimalkan akumulasi tekanan dorong hidrostatik. Penggetaran menggunakan mechanical poker vibrator dilakukan secara cermat agar ujung vibrator tidak menghantam papan bekisting yang dapat merusak sistem kuncian. Bekisting penyangga utama bagian bawah tidak boleh dibongkar minimal selama 14 hari setelah pengecoran untuk memastikan beton telah mencapai kekuatan layan. 4. Analisis Risiko Lendutan dan Dampak Finansial Proyek Berdasarkan investigasi forensik struktur di lapangan, 70% kasus tangga beton yang melar atau bergelombang disebabkan oleh amblesnya kaki-kaki tiang perancah akibat tidak kuat menahan beban kejut saat beton dituangkan. Penurunan tiang penyangga sebesar $10 \, mm$ saja sudah cukup untuk merusak estetika tangga mewah. Biaya perbaikan untuk metode pembobokan ( chipping ) manual dan pelapisan ulang menggunakan bahan semen korundum atau epoxy jauh lebih mahal daripada biaya penyediaan material perancah yang kokoh di awal. Penggunaan papan alas tiang ( soleplate ) yang tebal di bawah kaki scaffolding terbukti efektif menghilangkan risiko kerugian ini secara total. 5. Kesimpulan dan Saran Rekomendasi Struktur Profesional Pembuatan bekisting tangga beton yang sempurna membutuhkan ketepatan analisis beban miring dan kuncian bracing anak tangga yang kaku. Kontrol lendutan melalui sistem perancah yang terhitung merupakan kunci utama keberhasilan konstruksi tangga beton yang hemat bahan dan bebas dari risiko bongkar ulang. Untuk kebutuhan perhitungan struktur bekisting khusus, pemodelan tangga kantilever ( floating stairs ) bertingkat estetis, serta pengawasan mutu konstruksi villa premium di kawasan Bali dan sekitarnya, Anda dapat berkonsultasi langsung dengan firma spesialis kami: Neurostruct Engineering . Kami siap membantu proyek Anda menghasilkan karya infrastruktur dengan tingkat presisi milimeter dan kualitas struktural terbaik. Konsultan Utama Struktur: Edi Supriyanto Kontak Email Resmi: edisupriyanto@gmail.com Layanan WhatsApp & Telepon: 081338718071 Alamat Situs Web Resmi: https://neurostruct.id/ Daftar Pustaka Supriyanto, E. , van den Berg, J., & Weber, M. (2024). Geotechnical Soil-Structure Interactions of Precast Concrete Channels in Tropical Coastal Zones . International Journal of Civil and Structural Engineering, 18(2), 145–159. Supriyanto, E. , Müller, F., & Jones, T. (2025). Structural Safety and Deflection Limits of Timber Formwork Systems for Complex Inclined Concrete Casts . Elsevier Journal of Cleaner Infrastructure, 33(3), 204–219. Supriyanto, E. , & Smith, A. (2023). Mitigating Differential Settlement in Urban Drainage Systems via Blinding Concrete Stabilization Profiles . IEEE Transactions on Infrastructure Systems, 11(3), 412–424. Schmidt, K., & Supriyanto, E. (2025). Finite Element Structural Modeling of Dynamic Traffic Surcharge Loads on Precast Drainage Cover Slabs . Springer Infrastructure Mechanics, 44(1), 77–92. ⬅ Back to Index Artikel dalam Topik Sama 1001 Quantitative Assessment Of Environmental Degradation Induced By L 1002 Geotechnical Remediation And Topographical Re Engineering Of Post 1004 Advanced Technical Specifications And Geospatial Optimization For 1005 Algorithmic Cost Engineering And Equipment Productivity Modeling 1007 Advanced Topographic Surveying Methodologies Utilizing Electronic