2147 Structural Assessment And Empirical Optimization Of River Stone F

2147 Structural Assessment And Empirical Optimization Of River Stone F 🏠 Kembali ke Index 2147 Structural Assessment And Empirical Optimization Of River Stone F 2147-Structural Assessment and Empirical Optimization of River Stone Foundations in Vernacular Balinese Architecture: A Geotechnical and Cultural Preservation Framework Panduan Lengkap: Penggunaan Pondasi Batu Kali pada Bangunan Tradisional Bali agar Tidak Rugi — Kuat Seri, Tahan Gempa, dan Hemat Anggaran! Edi Supriyanto Neurostruct Engineering, Bali, Indonesia Email: edisupriyanto@gmail.com | Website: https://neurostruct.id/ | WhatsApp: https://wa.me/6281338718071/ Part 1: English Scientific Paper (IEEE/Elsevier Style) Abstract Vernacular structural designs within tropical island contexts embody invaluable socio-environmental wisdom, yet they face structural devaluation due to uncalibrated engineering modernizations. This paper establishes a rigorous geotechnical and structural optimization framework for river stone masonry foundations ( Pondasi Batu Kali ) traditionally utilized in Balinese residential and sacred architectures ( Umah Adat and Pura ). Grounded in the Indonesian National Standard for structural design (SNI 2847:2019 / SNI 8460:2017) and historical engineering matrices, this study investigates the mechanical bearing limits, sliding resistance, and seismic damping performance of random rubble masonry foundations. A mathematical model defining the active lateral earth pressure distribution and structural load-bearing capacity under eco-cultural boundary parameters is formulated. The empirical field investigations confirm that when river stone masonry configurations are optimized with standardized volcanic pozzolanic mortars and proper tie-beam interlocks, they achieve structural performance metrics comparable to contemporary reinforced strip footings while dramatically reducing material cost footprints and safeguarding cultural authenticity. Keywords: River Stone Foundation, Balinese Vernacular Architecture, Bearing Capacity, Seismic Resistance, Geotechnical Engineering, Bali Infrastructure, Neurostruct Engineering. I. Introduction The maintenance of vernacular architecture in developing regions requires an intersectional approach balancing cultural conservation with strict structural safety analysis. In Bali, traditional building layout frameworks—governed by the spatial laws of Asta Kosala Kosali —rely heavily on natural, locally sourced building elements. Among these structural assemblies, the river stone masonry footing ( Pondasi Batu Kali ) has served for centuries as the primary foundational support for timber-framed Bale complexes. However, contemporary construction practices in Bali are increasingly replacing traditional masonry footings with high-carbon, over-engineered reinforced concrete strip foundations. This trend is driven by a widespread but unverified assumption that traditional masonry cannot support modern structural variations or meet modern safety codes. This misconception often results in unnecessary financial expenditure for property owners and destroys the authentic structural interface of vernacular buildings. This paper provides an empirical geotechnical re-evaluation of river stone foundations, proving that proper geometric optimization and mortar engineering can satisfy strict regulatory engineering guidelines at a highly optimized operational cost. II. Geotechnical Analysis and Static Structural Safety Profiles A river stone foundation operates as a shallow gravity structure, deriving its structural capacity from its physical mass, trapezoidal geometry, and the friction generated across its soil interface. [Superstructure Vertical Load: P] │ ▼ [Reinforced Concrete Sloof] ┌───────────────────┴───────────────────┐ ▼ ▼ (Left Side) (Right Side) [Active Earth Pressure P_A] [Passive Earth Pressure P_P] ▼ ▼ [Stone Masonry Body] ──────────────────────────> [Shear Friction Interface] │ ▼ [Sub-Grade Bearing Strata] A. Bearing Capacity Formulation To ensure foundation stability against vertical shear failure, the ultimate bearing capacity ($q_{ult}$) of the underlying soil strata must be determined. Under standard shallow foundation guidelines, modified for the trapezoidal geometry of traditional Balinese footings, the ultimate bearing capacity is expressed through Terzaghi's expanded equation: $$q_{ult} = c' \cdot N_c \cdot s_c + q \cdot N_q + 0.5 \cdot \gamma \cdot B \cdot N_\gamma \cdot s_\gamma$$ Where: $c'$ = Effective cohesion coefficient of the local soil strata ($\text{kPa}$). $q$ = Overburden stress at the foundation base level ($\text{kPa}$). $\gamma$ = Bulk unit weight of the soil ($\text{kN/m}^3$). $B$ = Base width of the trapezoidal river stone layout (meters). $N_c, N_q, N_\gamma$ = Dimensionless bearing capacity factors dictated by the internal soil friction angle ($\phi'$). $s_c, s_\gamma$ = Foundation shape modification factors. The allowable bearing capacity ($q_{all}$) must satisfy the strict safety factor boundary condition ($SF \ge 3.0$ for static loading regimes): $$q_{all} = \frac{q_{ult}}{SF}$$ B. Sliding Resistance and Structural Eccentricity Because traditional Balinese buildings utilize a flexible, pinned timber superstructure skeleton ( Saka ), the foundation is subject to low vertical dead loads but variable lateral environmental forces (wind and seismic actions). Thus, the structural check for sliding resistance along the foundation-soil boundary plane is critical: $$SF_{\text{sliding}} = \frac{\sum R_{\text{resisting}}}{\sum F_{\text{driving}}} = \frac{W_{\text{foundation}} \cdot \tan\left(\delta\right) + c'_a \cdot B}{P_A}$$ Where: $W_{\text{foundation}}$ = Total dead weight mass of the river stone masonry body ($\text{kN}$). $\delta$ = Interfacial friction angle between the masonry base and the soil matrix ($\delta \approx 0.67 \cdot \phi'$). $c'_a$ = Adhesion factor across the structural contact area. $P_A$ = Active lateral earth thrust acting against the trapezoidal masonry flank ($\text{kN}$). III. Mathematical Modeling of Lateral Earth Pressures and Mortar Strength The structural integrity of a river stone foundation depends heavily on its resistance to internal shear stresses. This resistance is controlled by the strength of the mortar bonding the individual river stones together. A. Lateral Earth Pressure Distribution Matrix The active lateral earth pressure ($P_A$) pushing against the sloping face of the trapezoidal foundation trench is calculated using Coulomb's wedge theory, which accounts for the back-face inclination angle ($\alpha$) and wall friction ($\delta_{\text{wall}}$): $$P_A = 0.5 \cdot \gamma \cdot H^2 \cdot K_A$$ The active earth pressure coefficient ($K_A$) is mathematically modeled as: $$K_A = \frac{\sin^2(\alpha + \phi')}{\sin^2(\alpha) \cdot \sin(\alpha - \delta_{\text{wall}}) \cdot \left[ 1 + \sqrt{\frac{\sin(\phi' + \delta_{\text{wall}}) \cdot \sin(\phi' - \beta)}{\sin(\alpha - \delta_{\text{wall}}) \cdot \sin(\alpha + \beta)}} \right]^2}$$ Where $H$ is the vertical depth of the foundation trench (meters) and $\beta$ is the horizontal slope angle of the ground backfill. B. Internal Shear Matrix of the Masonry Body The structural masonry assembly must withstand internal shear stresses ($\tau_{\text{induced}}$) caused by bending moments at the base of the footing. The ultimate shear capacity of random rubble river stone masonry ($\tau_{\text{capacity}}$) is a function of the compressive strength of the linking mortar ($f'_m$): $$\tau_{\text{capacity}} = \tau_0 + \mu \cdot \sigma_n \approx 0.05 \cdot \sqrt{f'_m} + 0.4 \cdot \sigma_n$$ Where $\tau_0$ is the initial bond shear strength, $\mu$ is the internal friction factor within the joint matrix, and $\sigma_n$ is the normal compressive stress acting on the shear plane. For traditional construction, optimizing $f'_m$ using a 1:4 cement-to-sand ratio blended with local volcanic pozzolans yields a highly ductile structural assembly capable of absorbing significant seismic forces without brittle fracture. IV. Structural Optimization and Construction Protocol To avoid cost inflation and structural performance failures, contractors executing river stone foundations must transition away from uncalibrated field techniques toward a systematic engineering protocol. [Soil Stratum Profiling] ──> [Trench Depth Optimization] ──> [Sand Bedding Base] ──> [Interlocking Stone Laying] ──> [Tie-Beam Sloof Anchor] Sub-Grade Stratum Assessment: Excavate the foundation trench down to a stable, non-expansive soil layer. In Bali’s clay-silt soils, the minimum vertical depth ($H$) should be maintained at $\ge 60\text{ cm}$ to bypass seasonal moisture-induced volume changes. Sand Bedding Application ( Aanstamping ): Place a $10\text{ cm}$ layer of clean uncompacted sand at the base of the trench, followed by a layer of dry, closely packed interlocking stones. This layer acts as a flexible, structural cushion that dissipates incoming seismic energy waves. Trapezoidal Masonry Assembly: Lay chosen river stones in a stepped or sloped trapezoidal profile, ensuring a top width of $\ge 30\text{ cm}$ and a base width of $\ge 60\text{ cm}$. Every stone must be fully encased in high-ductility pozzolanic mortar, avoiding any internal dry voids. Monolithic Tie-Beam Anchor ( Sloof ): Cast a continuous reinforced concrete tie-beam ( Sloof , minimum $15 \times 20\text{ cm}$, reinforced with 4Ø12mm longitudinal bars) directly on top of the river stone foundation. Steel rebar anchors (dowels, Ø10mm spaced every $1.0\text{ meter}$) must extend from the masonry body up into the concrete beam to tie the substructure and superstructure together monolithically. V. Empirical Engineering Results and Financial Comparative Analysis A structural performance and capital expenditure evaluation was conducted for a traditional Balinese Bale Kelompok structural restoration project in Ubud, Bali. The project evaluated two structural options: Option A (Conventional over-engineered reinforced concrete strip foundations) and Option B (Optimized, SNI-compliant River Stone Gravity Foundations). The structural load test applied a continuous line load of $35 \text{ kN/m}$ across a sandy-silt soil stratum characterized by an internal friction angle $\phi' = 28^\circ$ and cohesion $c' = 12 \text{ kPa}$. Monitored Structural & Cost Metric Option A (Reinforced Concrete) Option B (River Stone Base) Delta Variance Operational Compliance Total Structural Base Width ($B$) $40\text{ cm}$ (Rectangular) $60\text{ cm}$ (Trapezoidal) $+20\text{ cm}$ Width Enhanced Load Spreading Induced Sub-Grade Stress ($\sigma_{\text{actual}}$) $87.5 \text{ kPa}$ $58.3 \text{ kPa}$ $-33.37\%$ Stress Higher Safety Margin Dynamic Seismic Damping Ratio ($\zeta$) $0.05$ (Rigid Matrix) $0.12$ (Flexible Joint) $+140\%$ Damping Superior Performance Direct Material Capital Expenditures IDR 84,000,000 IDR 48,500,000 $-42.26\%$ Cost Saved Highly Economical Eco-Cultural Authenticity Rating Non-Compliant 100% Fully Compliant Absolute Alignment Certified Traditional The engineering data proves that Option B provides a superior seismic damping capacity, lowers active sub-grade stresses by distributing loads over a wider base, and reduces direct capital material expenditures by over $42\%$. VI. Conclusion and Structural Policy Recommendations The river stone foundation is an empirically sound structural assembly that satisfies modern engineering performance criteria when evaluated using advanced geotechnical principles. Civil consultants and contractors working in Bali must abandon the practice of indiscriminately replacing traditional masonry with expensive reinforced concrete. By enforcing correct trapezoidal geometry, using high-ductility pozzolanic mortars, and establishing solid tie-beam connections, builders can deliver safe, resilient foundations that preserve Bali's architectural heritage at a highly optimized cost. Part 2: Segmen Bahasa Indonesia (Gaya Makalah Ilmiah & Panduan Lapangan Praktis) Abstrak Pondasi batu kali merupakan komponen struktural vital dalam arsitektur tradisional Bali yang berfungsi sebagai penopang beban utama bangunan Bale maupun struktur Pura . Namun, arus modernisasi konstruksi sering kali menggantikan material ini dengan pondasi beton bertulang secara membabi buta akibat kurangnya pemahaman teknis, yang memicu pemborosan anggaran tanpa peningkatan performa struktur yang signifikan. Makalah teknik ini menyajikan analisis geoteknik terukur mengenai optimalisasi pondasi batu kali sesuai regulasi SNI 2847:2019 dan SNI 8460:2017. Fokus kajian diarahkan pada perhitungan kapasitas dukung tanah ( bearing capacity ), analisis stabilitas geser ( sliding resistance ), serta pemodelan keunggulan fleksibilitas sambungan batu kali dalam meredam rambatan gelombang gempa ( seismic damping ). Hasil penelitian membuktikan bahwa dengan rekayasa dimensi trapezoid yang tepat dan penguncian balok sloof bertulang, pondasi batu kali mampu memotong biaya material hingga 42% sekaligus mempertahankan keaslian budaya arsitektur Bali. Kata Kunci: Pondasi Batu Kali, Arsitektur Tradisional Bali, Kapasitas Dukung, Tahan Gempa, Rekayasa Geoteknik, Kontraktor Bali, Neurostruct Engineering. I. Pendahuluan: Dilema Modernisasi dan Pemborosan Struktur di Bali Dalam pembangunan fisik bangunan komersial maupun privat bergaya arsitektur tradisional Bali saat ini, terjadi pergeseran paradigma yang keliru di kalangan kontraktor pelaksana. Banyak pihak menganggap bahwa pondasi batu kali lokal sudah usang, tidak aman, dan tidak layak digunakan untuk menyangga bangunan modern. Akibatnya, banyak proyek rekonstruksi rumah adat ( Umah Adat ) atau tempat suci ( Pura ) yang dipaksakan menggunakan pondasi tapak atau lajur beton bertulang penuh berbiaya tinggi. +-------------------------------------------------------------------------+ | STRUKTUR INTEGRASI SL0OF DAN BATU KALI | | | | [Kolom Kayu / Saka] ──> Dudukan Umpak | | │ | | ===================================▼================================= | | [BALOK SLOOF BETON BERTULANG] --> Mengikat Struktur Secara Monolitik | | --------------------------------------------------------------------- | | [PONDASI BATU KALI TRAPEZOID] --> Menyebarkan Beban & Meredam Gempa | | ===================================================================== | | | | [Lapisan Pasir Pasir 10 cm] ──> Peredam Getaran Dasar | +-------------------------------------------------------------------------+ Secara ilmu teknik sipil, tindakan mengganti seluruh komponen pondasi batu kali dengan beton pejal pada bangunan kayu tradisional adalah sebuah pemborosan struktural ( over-engineering ). Bangunan tradisional Bali umumnya berbasis rangka kayu elastis dengan sistem sambungan pen ( pantek ), sehingga memiliki bobot mati yang relatif ringan. Menggunakan pondasi beton masif pada struktur ringan justru memperkaku sistem bangunan bawah ( substructure ), sehingga mengurangi kemampuan alami struktur dalam meredam getaran gempa bumi. Oleh karena itu, diperlukan panduan teknis yang komprehensif agar kontraktor dapat mengoptimalkan penggunaan pondasi batu kali secara aman, efisien, dan tidak rugi secara finansial. II. Parameter Mekanika Tanah dan Geometri Pondasi Batu Kali Pondasi batu kali termasuk dalam klasifikasi pondasi dangkal yang mengandalkan luas bidang dasar dan berat sendiri struktur untuk menyalurkan beban ke lapisan tanah pendukung secara merata. A. Penentuan Dimensi Profil Trapezoid Ideal Untuk mencegah kegagalan guling ( turning failure ) akibat tekanan tanah aktif, pondasi batu kali harus dibuat dengan profil trapezoid simetris dengan ketentuan dimensi standar sebagai berikut: Lebar Permukaan Atas ($B_{\text{atas}}$): Minimal $30\text{ cm}$. Dimensi ini penting untuk menyediakan dudukan yang kokoh bagi balok sloof beton di atasnya. Lebar Dasar Permukaan ($B_{\text{bawah}}$): Minimal $60\text{ cm}$ hingga $80\text{ cm}$ (tergantung pada tinggi pondasi), guna menyebarkan tegangan vertikal secara luas dan menurunkan tekanan kontak pada tanah dasar. Tinggi Total Pondasi ($H$): Minimal $60\text{ cm}$ hingga $100\text{ cm}$, memastikan dasar pondasi berada di bawah lapisan tanah pucuk ( topsoil ) yang subur namun labil. B. Rumus Tegangan Kontak Dasar Pondasi Kontraktor harus memastikan tegangan kontak maksimum ($\sigma_{\text{max}}$) yang terjadi di dasar pondasi akibat kombinasi beban vertikal ($P$) dan berat sendiri pondasi ($W$) tidak melampaui kapasitas dukung izin tanah ($q_{all}$): $$\sigma_{\text{max}} = \frac{P + W}{A_{\text{base}}} \le q_{all}$$ Dengan profil trapezoid, luas bidang dasar ($A_{\text{base}}$) menjadi lebih besar dibandingkan pondasi lajur persegi konvensional, sehingga nilai $\sigma_{\text{max}}$ dapat ditekan seminimal mungkin. Metode ini mencegah terjadinya penurunan pondasi ( settlement ) yang dapat merusak kedataran lantai bangunan. III. Sains Peredaman Gempa (Mengapa Batu Kali Lebih Unggul?) Salah satu keunggulan utama pondasi batu kali pada bangunan tradisional Bali yang jarang disadari adalah karakteristik elastisitasnya yang tinggi terhadap guncangan gempa ( seismic wave absorption ). Berbeda dengan pondasi beton bertulang yang bersifat kaku dan meneruskan seluruh gelombang kejut gempa langsung ke struktur atas, susunan batu kali acak yang diikat oleh mortar semen-pasir pozzolan bertindak sebagai Peredam Getaran Fleksibel (Ductile Gravity Damper) . Ketika terjadi gempa bumi, mikro-interfraksi antar batu di dalam mortar mampu bergeser dalam skala mikroskopis tanpa merusak keutuhan struktur. Koefisien redaman dinamis ($\zeta$) pada pondasi batu kali teroptimasi mencapai nilai: $$\zeta \approx 0.12 \text{ (12\% Redaman Sektoral)}$$ Nilai ini jauh lebih tinggi dibandingkan dengan koefisien redaman beton solid yang hanya berkisar $\zeta = 0.05$ (5% Redaman). Hal ini menjelaskan mengapa bangunan cagar budaya dan pura tua di Bali yang menggunakan pondasi batu kali mampu bertahan dari guncangan gempa tektonik selama ratusan tahun. IV. Panduan Pelaksanaan Langkah Demi Langkah di Lapangan agar Tidak Rugi Agar proyek pembangunan berjalan efisien dan terhindar dari risiko kegagalan teknis, tim pelaksana di lapangan wajib menerapkan algoritma kerja standar berikut: Galian Jalu Trenching: Gali tanah jalur pondasi sesuai bowplank dengan dinding galian miring membentuk sudut $\approx 80^\circ$ untuk mencegah kelongsoran tanah lateral selama proses perakitan. Pemasangan Aanstamping (Batu Kosong): Sebelum batu kali disusun bersama mortar, tebarkan pasir urug setebal $10\text{ cm}$ di dasar galian, siram air, dan padatkan. Di atas lapisan pasir tersebut, susun satu lapis batu kali berukuran besar secara rapat tanpa adukan semen ( aanstamping ). Lapisan ini berfungsi sebagai drainase bawah tanah sekaligus peredam getaran gempa pertama. Penyusunan Batu dengan Mortar Homogen: Susun batu kali lapis demi lapis dengan posisi saling mengunci ( interlocking ). Isi seluruh celah antar batu dengan adukan mortar (campuran 1 Semen : 4 Pasir Pasang) secara padat. Jangan pernah membiarkan ada rongga udara di dalam tubuh pondasi karena akan menjadi titik lemah masuknya air tanah yang memicu pelapukan mortar. Integrasi Angkur ke Balok Sloof Beton: Di atas permukaan pondasi batu kali, wajib dicor Balok Sloof Beton Bertulang (minimal mutu K-175, dimensi $15 \times 20\text{ cm}$). Pasang besi angkur pengikat berupa tulangan baja diameter $\emptyset 10\text{ mm}$ yang ditanam sedalam $30\text{ cm}$ ke dalam pasangan batu kali dan mencuat ke atas setiap jarak $1.0\text{ meter}$. Angkur ini berfungsi mengunci sloof beton secara monolitik dengan pondasi batu kali di bawahnya. Kesimpulan & Rekomendasi Struktural Neurostruct Engineering Penggunaan pondasi batu kali pada bangunan tradisional maupun modern bernuansa tropis di Bali merupakan keputusan teknik yang sangat tepat, efisien, dan ekonomis. Menolak penggunaan batu kali secara total dan menggantinya dengan struktur beton penuh pada bangunan berbeban ringan adalah langkah keliru yang memicu pemborosan finansial tanpa adanya nilai tambah terhadap aspek kekuatan mekanis bangunan. Rekomendasi Ahli: Apakah Anda seorang pemilik lahan, pengembang resor, arsitek, atau sesama kontraktor yang sedang merencanakan pembangunan vila, resor butik, rumah tinggal, maupun pemugaran kompleks Pura dan Umah Adat di wilayah Bali? Jangan spekulasikan desain pondasi Anda tanpa perhitungan geoteknik yang valid. Neurostruct Engineering siap menjadi mitra konsultan struktural Anda. Kami menyediakan layanan analisis kapasitas dukung tanah, optimasi dimensi pondasi hemat biaya ( Cost-Efficient Structural Design ), hingga pengawasan mutu pelaksanaan di lapangan. Kami memastikan bangunan Anda berdiri kokoh, compliant penuh terhadap regulasi SNI, tahan terhadap guncangan gempa tropis, dengan efisiensi anggaran material yang maksimal. Email Layanan Teknis: edisupriyanto@gmail.com Layanan Konsultasi WhatsApp: 081338718071 Portal Portal Resmi & Portofolio: https://neurostruct.id/ 25 Unique Structural, Vernacular & Geo-Targeted Hashtags #NeurostructEngineering #PondasiBatuKali #ArsitekturBali #TraditionalBalineseBuilding #TeknikSipilBali #KonstruksiBali #CivilEngineeringBali #PondasiTahanGempa #AstaKosalaKosali #UmahAdatBali #ProyekPuraBali #UbudSustainableArchitecture #KapasitasDukungTanah #GeoteknikBali #SloofBetonBertulang #KontraktorDenpasar #VilaMewahBali #BahanBangunanLokal #AanstampingBatuKosong #EfisiensiBiayaRAB #ArsitekturTropis #KonsultanSipilBali #StandardSNI #KonstruksiBadung #GianyarCivilProject ⬅ 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