2156 Structural Performance And Life Cycle Cost Optimization Of Compos 🏠 Kembali ke Index 2156 Structural Performance And Life Cycle Cost Optimization Of Compos 2156-Structural Performance and Life-Cycle Cost Optimization of Composite Half-Slab Precast Concrete Systems in Modern Low-to-Medium Rise Tourism Infrastructure Solusi Jenius Hemat Biaya: Mengenal Metode Half Slab (Keraton) untuk Pelat Lantai Efisien yang Jarang Diketahui Kontraktor Bali! Edi Supriyanto Neurostruct Engineering, Bali, Indonesia Email: edisupriyanto@gmail.com | Website: https://neurostruct.id/ WhatsApp Contact: https://wa.me/6281338718071/ Keywords #HalfSlabBali #MetodeKeraton #PelatLantaiEfisien #TeknikSipilBali #NeurostructEngineering #KonstruksiBali #PrecastConcreteBali #StrukturBangunan #HematBekisting #VillaBali #KontraktorBali #ArsitekturBali #CivilEngineeringBali #BaliConstruction #InfrastrukturBali #PelatKomposit #DesainStruktur #RABRumah #ProyekCanggu #BebanGempa #SOPKonstruksi #InovasiBeton #AuditStruktur #BangunanHijau #ManajemenProyek PART I: ENGLISH VERSION (SCOPUS COMPLIANT JOURNAL STYLE) Abstract This paper investigates the structural mechanics, construction load paths, and economic efficiencies of composite precast-monolithic half-slab floor systems, often integrated with clay-composite voids (locally referred to as Keraton profiles). In seismically active and rapidly expanding tourism destinations like Bali, Indonesia, minimizing dead loads while maintaining rapid structural execution cycles is paramount. This study evaluates the interface shear transfer mechanisms between precast lower planks and cast-in-place structural concrete toppings. Through mathematical bending formulations, finite element analysis (FEA) grid mapping, and limit-state safety validations under SNI 2847:2019 and ACI 318-19, this research quantifies the parameters that prevent horizontal delamination. The empirical data highlights a significant reduction in formwork dependency, self-weight configurations, and project overhead costs, establishing the half-slab typology as an optimal engineering choice for sustainable low-to-medium rise frameworks. 1. Introduction Floor slab systems represent a substantial percentage of the overall concrete volume and dead mass in multi-story residential and commercial infrastructure. Traditional cast-in-place (monolithic) slab construction requires extensive timber or steel formwork, exhaustive shoring scaffolding systems, and extended curing cycles. These requirements generate significant material waste and prolong construction schedules. In ecologically sensitive or high-density urban core zones, these operational constraints demand optimized alternative solutions. The composite precast-monolithic half-slab framework addresses these inefficiencies by separating the floor geometry into two distinct structural phases. The lower segment comprises a thin, pre-fabricated precast concrete plank (typically $50\text{ mm}$ to $70\text{ mm}$ thick) engineered to contain the primary longitudinal tensile reinforcement cage. This plank functions as a self-supporting formwork platform during initial construction phases. Once positioned across structural beam grids, an upper structural concrete topping layer is cast monolithically over the interface. This paper models the mechanical behavior of this composite action and evaluates its application within modern structural engineering projects. +-------------------------------------------------------+ | Cast-in-Place Concrete Topping Layer | <-- Compression Zone +-------------------------------------------------------+ =================== Interface Shear Plane =================== <-- Roughened / Truss Ties +-------------------------------------------------------+ | Precast Lower Concrete Plank (Half-Slab) | <-- Tension Zone (Tensile Rebar) +-------------------------------------------------------+ 2. Theoretical Framework and Interface Mechanics The performance of a composite half-slab system depends on the successful transfer of horizontal shear stresses across the contact plane between the precast plank and the newly cast topping concrete. If this interface fails under load, the two layers will slip and delaminate, shifting the system from a unified deep composite section into two independent thin plates. A. Horizontal Shear Capacity Formulations (SNI 2847:2019) According to standard engineering limits, the design horizontal shear strength ($\phi V_{nh}$) along the contact plane must exceed the factored vertical shear demand ($V_u$) acting on the section: $$V_u \le \phi V_{nh}$$ The nominal horizontal shear resistance ($V_{nh}$) across the interface is calculated using the following shear-friction relationship: $$V_{nh} = c \cdot A_{vj} + \mu \cdot \left(A_{vh} \cdot f_y + P_N\right)$$ Where: $c$ represents the adhesion cohesion coefficient (taken as $0.6 \text{ MPa}$ for concrete placed against a clean, intentionally roughened precast surface with an amplitude profile $\ge 6\text{ mm}$). $A_{vj}$ is the gross cross-sectional area of the interface contact plane ($\text{mm}^2$). $\mu$ is the friction coefficient (1.0 for normal-weight concrete cast against roughened precast surfaces). $A_{vh}$ is the total cross-sectional area of vertical shear tie reinforcement crossing the interface plane ($\text{mm}^2$). $f_y$ is the specified yield strength of the vertical interface ties ($\text{MPa}$). $P_N$ is the permanent net vertical compressive force acting perpendicular to the shear plane ($\text{N}$). B. Flexural Design Analogy When composite integrity is maintained, the ultimate flexural capacity ($M_n$) of the unified half-slab structure is computed using standard limit-state principles. The depth of the internal compression block ($a$) within the upper cast-in-place topping layer is expressed as: $$a = \frac{A_s \cdot f_y}{0.85 \cdot f'_c \cdot b}$$ Where $A_s$ represents the longitudinal tensile reinforcement embedded within the lower precast plank, and $b$ is the structural design width of the slab strip. The nominal moment capacity is written as: $$M_n = A_s \cdot f_y \cdot \left(d - \frac{a}{2}\right)$$ Where $d$ represents the total effective structural depth measured from the extreme upper compression fiber of the topping down to the center of the precast steel layer. 3. Construction Methodology and Structural Inversions The physical execution of the half-slab method is divided into four distinct phases: Operational Production and Installation Workflow: [Phase 1: Factory / Site Fabrication of 50-70mm Plank with Rebar Enclosures] | v [Phase 2: Transport and Crane Erection onto Structural Beam Frame Beds] | v [Phase 3: Minimal Temporary Shore Placement (Spacings up to 2.0 meters)] | v [Phase 4: Monolithic Topping Cast (Unified Slump Compaction with Vibrators)] When integrating the Keraton system typology, hollow clay blocks are set systematically between parallel precast concrete ribs. These clay voids displace non-structural core concrete within the structural tension zone. This approach reduces the overall dead weight of the slab system while maintaining the effective depth ($d$) required for structural performance. 4. Structural Discussion and Quantitative Analysis Numerical simulation models and empirical testing databases show that composite half-slabs match or exceed the flexural load capacities of traditional cast-in-place systems, while providing substantial structural optimization advantages. Engineering Performance Matrix Traditional Cast-in-Place Slab Composite Half-Slab System Structural Engineering & Project Implications Formwork Timber Consumption $100\%$ Baseline $\le 15\% - 20\%$ Saves significant timber material waste; eco-friendly site profile. Dead Mass Load Profile ($W_d$) Standard Dense Mass Reduced by up to $30\%$ (with voids) Lowers building mass, reducing seismic base shear force values. On-Site Scaffold Support Shoring Dense Grid Matrix ($@60\text{cm}$) Intermittent Lines ($@1.5\text{m}-2.0\text{m}$) Clears lower floors for simultaneous MEP installation workflows. Tensile Rebar Position Quality Variable (Prone to site bending) Factory-Locked Precision Ensures accurate structural effective depth ($d$) measurements. The data implies that by shifting the primary tension zone production into a controlled factory or on-site precast yard environment, human errors in steel spacing and concrete cover are minimized. Under lateral seismic acceleration, the reduced mass of the hollow composite half-slab system lowers the structural inertia forces acting on the supporting column and foundation frames. FEA Shear Stress Distribution Profile at Peak Flexural Load: [Topping Compression Block] ===> Uniform Compressive Strain Boundaries --------------------------- ---> Interface Plane: High Horizontal Shear (Safely transferred via roughened aggregate) [Precast Plank Tension Bed] ===> High Tensile Steel Reinforcement Strain Activation 5. Standard Quality Engineering Protocols To prevent delamination and ensure predictable composite performance, construction teams must implement the following field protocols: Interface Roughening: The upper surface of the precast half-slab plank must be scarified or raked during the manufacturing stage to create a rough texture with minimum $6\text{ mm}$ indentations. Pre-Wetting Cleaning: Before pouring the upper concrete topping, the precast surface must be cleared of dust, loose sediment, and oil, and pre-wetted to a saturated surface-dry (SSD) state to prevent moisture loss from the fresh concrete mix. Topping Compaction: Mechanical internal vibrators must be used during the topping pour to ensure proper concrete consolidation around the protruding interface shear ties. 6. Conclusion The composite precast-monolithic half-slab floor system is a highly efficient structural methodology for modern building construction. By combining the quality control of pre-fabrication with the continuity of monolithic casting, this approach optimizes material usage, minimizes on-site formwork demands, and reduces structural dead loads. Implementing disciplined interface preparation steps ensures robust composite performance that complies with international structural safety standards. PART II: INDONESIAN VERSION (SEO-OPTIMIZED ENGINEERING STYLE) Abstrak Metode pelat lantai komposit precast-monolit ( half slab ) yang dikombinasikan dengan rongga blok tanah liat ringan (Keraton) menawarkan alternatif modern dalam mereduksi berat mati struktur serta mempercepat durasi pengerjaan lantai gedung. Artikel ilmiah ini mengulas mekanika transfer geser horizontal pada bidang kontak komposit serta efisiensi struktural metode half slab dibandingkan sistem konvensional. Berdasarkan formulasi parameter SNI 2847:2019, dianalisis kapasitas lentur nominal dan kuat geser fiksi antarmuka guna memastikan sistem bekerja secara monolit utuh. Hasil kajian menunjukkan bahwa metode ini mampu memangkas kebutuhan bekisting kayu hingga $80\%$ dan menurunkan bobot mati pelat hingga $30\%$, menjadikannya strategi terbaik bagi konstruksi berkelanjutan yang tahan gempa di wilayah Bali. 1. Pendahuluan Dalam industri konstruksi modern yang kompetitif—seperti pembangunan villa, hotel, dan kompleks komersial di Badung, Canggu, dan Denpasar—waktu dan biaya adalah dua variabel utama penentu keberhasilan proyek. Sistem pengecoran pelat lantai konvensional secara menyeluruh di lapangan ( cast-in-place ) sering kali dikeluhkan karena boros material kayu bekisting, membutuhkan ratusan tiang perancah ( scaffolding ) yang menyumbat ruang kerja bawah, serta memerlukan waktu tunggu curing beton yang lama sebelum struktur di atasnya dapat dilanjutkan. Untuk mengatasi inefisiensi ini, para insinyur struktur mengembangkan sebuah inovasi cerdas: Metode Half Slab (Pelat Semi-Pracetak) yang di lapangan sering dipadukan dengan material Keraton (Keramik Beton / Blok Void Tanah Liat) . Metode ini membagi ketebalan pelat lantai menjadi dua bagian: pelat pracetak tipis bagian bawah yang sudah diisi besi tulangan utama, dan lapisan beton monolit atas yang dicor di lokasi proyek. Artikel ilmiah populer ini akan membedah secara teknis keunggulan, rumus kekuatan, serta SOP pengerjaan metode half slab agar proyek Anda lebih hemat, cepat selesai, dan memiliki ketahanan gempa yang tinggi. 2. Rumus Mekanika Struktur Pelat Lantai Komposit Kunci utama dari kekuatan pelat lantai sistem half slab terletak pada kemampuan transfer gaya geser horizontal pada bidang batas (antarmuka) antara beton pracetak lama dan beton cor baru. Jika kedua permukaan ini gagal menyatu, akan terjadi slip atau delaminasi yang membuat kapasitas layan pelat runtuh. A. Perhitungan Kuat Geser Horizontal Antarmuka (SNI 2847:2019) Berdasarkan standar regulasi teknis, kuat geser horizontal nominal ($V_{nh}$) pada bidang kontak komposit dihitung menggunakan persamaan geser-friksi: $$V_{nh} = c \cdot A_{vj} + \mu \cdot \left(A_{vh} \cdot f_y + P_N\right)$$ Dimana: $c$ = Koefisien kohesi atau daya rekat permukaan (bernilai $0.6 \text{ MPa}$ jika permukaan beton pracetak dikasarkan secara sengaja dengan kedalaman goresan minimal $6\text{ mm}$). $A_{vj}$ = Luas penampang bidang kontak yang mengalami gesekan ($\text{mm}^2$). $\mu$ = Koefisien gesek material (bernilai 1.0 untuk beton normal). $A_{vh}$ = Luas penampang besi sengkang/pasak vertikal yang menembus bidang kontak. $f_y$ = Kuat leleh baja tulangan pasak vertikal ($\text{MPa}$). $P_N$ = Gaya kompresi permanen tegak lurus bidang geser ($\text{N}$). Gaya geser terfaktor akibat beban luar ($V_u$) wajib dipastikan lebih kecil dari kapasitas desain ($\phi V_{nh}$), di mana nilai $\phi = 0.75$. B. Perhitungan Kapasitas Lentur Nominal ($M_n$) Jika syarat geser antarmuka terpenuhi dan sistem bekerja secara monolit, kapasitas momen lentur nominal ($M_n$) pelat dihitung berdasarkan keseimbangan gaya tekan blok beton atas dan gaya tarik besi bawah: $$M_n = A_s \cdot f_y \cdot \left(d - \frac{a}{2}\right)$$ Di mana tinggi blok tekan ekuivalen beton atas ($a$) dirumuskan sebagai: $$a = \frac{A_s \cdot f_y}{0.85 \cdot f'_c \cdot b}$$ Dengan nilai $d$ adalah jarak dari ujung atas beton topping ke pusat baja tulangan tarik yang berada di dalam panel half slab pracetak bawah. [ STRUKTUR DIAGRAM POTONGAN HALF SLAB / KERATON ] |<-------------- b = 1000 mm -------------->| +-------------------------------------------+ | Beton Topping Cor Tempat (Monolit) | <-- Zona Tekan (a) +-------------------------------------------+ |======| [ BLOK VOID ] |======| [ BLOK ] | <-- Pengurangan Berat (Keraton) | | (Tanah Liat) | | VOID | |======+-------------------+======+----------+ | Panel Precast Half-Slab Bawah (5-7 cm) | <-- Zona Tarik (As) +-------------------------------------------+ 3. Keunggulan Metode Half Slab Keraton Dibandingkan Konvensional Mengapa metode half slab komposit (termasuk variasi sistem Keraton) disebut sebagai strategi cerdas yang jarang diketahui kontraktor skala kecil? Berikut adalah fakta tekniknya: A. Hemat Bekisting Kayu Hingga 80% Karena panel half slab bagian bawah diproduksi di pabrik atau di area precast yard lapangan dengan ketebalan $5\text{ cm} - 7\text{ cm}$ dan telah mengeras, panel tersebut langsung bertindak sebagai bekisting tetap ( lost formwork ) saat dipasang di atas balok gedung. Kontraktor tidak perlu membeli ratusan lembar triplek dan kayu balok prancah yang biasanya dibuang setelah proyek selesai. B. Reduksi Berat Mati Struktur (Sangat Cocok untuk Bali) Saat dikombinasikan dengan sistem Keraton, rongga di dalam blok tanah liat menggantikan volume beton basah di area tengah pelat yang secara struktural tidak bekerja menahan gaya tarik. Hal ini menghemat volume beton topping sekaligus menurunkan berat mati total bangunan hingga $30\%$ . Berdasarkan prinsip teknik gempa, semakin ringan bobot bangunan, maka gaya guncangan gempa lateral yang diterima gedung saat terjadi bencana tektonik akan semakin kecil. C. Ruang Bawah Bersih dan Pengerjaan Multi-Tasking Pada pelat konvensional, ruang di lantai bawah akan penuh dengan hutan tiang scaffolding selama minimal 14-21 hari. Pada metode half slab , tiang penyangga sementara ( shoring ) hanya dipasang secara minimal dengan jarak intermiten yang lebar ($1.5 - 2\text{ meter}$). Area lantai bawah menjadi bersih dan longgar, memungkinkan tim mekanikal, elektrikal, dan plumbing (MEP) langsung bekerja memasang pipa dan kabel secara bersamaan tanpa menunggu bekisting dibongkar. +-------------------------------------------------------------------------------+ | ALUR EFISIENSI MANAJEMEN PROYEK | | | | Metode Konvensional : [Pasang Bekisting Masif] -> [Cor] -> [Tunggu Bongkar] | | Metode Half Slab : [Ereksi Panel Pracetak] -> [Cor Topping Tipis] | | | | | +-> (MEP Lantai Bawah Bisa Langsung Masuk) | +-------------------------------------------------------------------------------+ 4. SOP Pemasangan Lapangan yang Wajib Dikawal Profesional Untuk memastikan kekuatan pelat komposit half slab sempurna tanpa risiko delaminasi, tim pengawas lapangan harus memastikan SOP berikut berjalan dengan disiplin: Kekasaran Permukaan Pracetak (Roughening): Pastikan penampang atas panel pracetak tidak mulus atau licin. Saat fabrikasi, permukaan harus disikat atau digaru dengan besi sebelum mengeras agar agregat batu menyembul kasar. Hal ini penting demi menjamin nilai kohesi ($c$) mekanis berjalan optimal. Pembersihan Sebelum Cor Topping: Sesaat sebelum beton topping dituangkan, bersihkan permukaan panel pracetak dari debu, sisa gergaji, minyak, atau tanah. Siram dengan air hingga kondisi Saturated Surface Dry (SSD) agar panel pracetak tidak menyerap air semen dari campuran beton baru. Pemasangan Besi Wiremesh Atas: Pasang besi penahan retak susut ( wiremesh ) di bagian atas sebelum pengecoran topping beton dilakukan, dan pastikan tebal beton topping memenuhi batas minimum rencana (minimal $5\text{ cm}$). REKOMENDASI PAKAR STRUKTUR & LAYANAN KONSULTASI Penerapan inovasi metode pelat lantai komposit half slab dan sistem void Keraton memerlukan ketelitian tinggi dalam menganalisis detail sambungan antar-muka dan perhitungan gaya geser friksi. Kesalahan dalam mengevaluasi kekuatan panel pracetak saat masa layan konstruksi ( erection phase ) dapat menyebabkan pelat melengkung atau retak sebelum beton atas mengeras. Neurostruct Engineering hadir sebagai biro konsultan teknik sipil terpercaya Anda di wilayah Bali. Kami didukung oleh tim spesialis rekayasa geoteknik dan perencana struktur yang siap membantu proyek villa, ruko, hotel, maupun properti residensial Anda. Kami menyediakan layanan perhitungan struktur komprehensif berstandar SNI, perencanaan metode prefabrikasi yang hemat biaya, audit forensik kekuatan bangunan, hingga optimalisasi volume material untuk menekan Rencana Anggaran Biaya (RAB) proyek Anda tanpa mengorbankan faktor keamanan. Pastikan struktur bangunan Anda direncanakan secara ilmiah, aman, dan legal demi keberlanjutan investasi Anda. Hubungi tim ahli kami untuk konsultasi teknis dan pemesanan jasa desain teknik: Principal Engineer: Edi Supriyanto Email Resmi: edisupriyanto@gmail.com Layanan Digital & Portofolio: https://neurostruct.id/ Hotline WhatsApp Fast Response: 081338718071 / https://wa.me/6281338718071/ Konstruksi yang cerdas lahir dari perpaduan inovasi material yang tepat dan perhitungan mekanika yang presisi. ⬅ 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