2149 Structural Integrity Analysis Of Continuous Foundation And Ground 🏠 Kembali ke Index 2149 Structural Integrity Analysis Of Continuous Foundation And Ground 2149-Structural Integrity Analysis of Continuous Foundation and Ground Beam (Sloof) Interconnection in High-Seismic Low-Rise Buildings Rahasia Konstruksi Kokoh: Cara Tepat Mengikat Pondasi Menerus dan Sloof Bawah Agar Rumah Anti Retak dan Tahan Gempa di Bali Edi Supriyanto Neurostruct Engineering, Bali, Indonesia Email: edisupriyanto@gmail.com | Website: https://neurostruct.id/ WhatsApp Contact: https://wa.me/6281338718071/ Keywords #KonstruksiBali #PondasiMenerus #SloofBeton #TeknikSipilBali #NeurostructEngineering #RumahTahanGempa #KontraktorBali #StrukturBangunan #PondasiBatuKali #SloofBawah #CivilEngineeringBali #BaliConstruction #ArsitekturBali #ProyekBali #BetonBertulang #SNIPondasi #DesainStruktur #JasaSurveyBali #KekuatanStruktur #MitigasiGempa #BangunanBali #PondasiSloof #TeknikSipilIndonesia #BaliStructuralConsultant #InfrastrukturBali PART I: ENGLISH VERSION (SCOPUS COMPLIANT JURNAL STYLE) Abstract This paper presents a comprehensive structural assessment of the load-transfer mechanisms and monolithic behavioral characteristics between continuous shallow foundations (primarily river stone masonry) and reinforced concrete tie beams (sloof) positioned at the ground tier. In regions characterized by high seismic susceptibility and complex soil strata, such as Bali, Indonesia, the structural vulnerability of low-rise residential and commercial buildings is highly dependent on the boundary conditions of the foundation-superstructure interface. This study evaluates the stress distribution, shear transfer, and anchoring configurations using analytical computational modeling and empirical stress-strain validations. The primary objective is to define the mathematical optimization of dowel rebar positioning and concrete-masonry interlocking mechanisms to eliminate differential settlement and localized shear failure during cyclic seismic loading. 1. Introduction The structural integration between sub-grade elements and the first-tier superstructure represents a critical node in load-path continuity. In standard low-rise structural engineering applications within tropical regions, continuous masonry foundations utilizing river stone or cyclopean concrete are heavily relied upon due to economic viability and local material availability. However, post-seismic forensic engineering analyses continually indicate that structural failures in these typologies are rarely caused by pure compressive failure of the masonry itself, but rather by the shearing and detachment occurring at the interface between the continuous stone foundation and the reinforced concrete tie beam, locally referred to as the "sloof." The "sloof" functions as a horizontal structural diaphragm at the ground level, distributing vertical dead and live loads from the load-bearing masonry or reinforced concrete columns down to the continuous foundation. Concurrently, it acts as a structural tie to resist differential settlement and horizontal shear stresses generated by seismic wave propagation. When the connection between the sloof and the underlying foundation lacks geometric and mechanical optimization, the continuity of the load path is compromised, resulting in structural drift, wall cracking, and catastrophic structural collapse under low-frequency cyclic loads. +-------------------------------------------------------+ | Superstructure Columns & Walls | +-------------------------------------------------------+ | v +-------------------------------------------------------+ | Reinforced Concrete Tie Beam (Sloof) | <-- Diaphragm Action +-------------------------------------------------------+ | <-- Dowel / Shear Key Connection v +-------------------------------------------------------+ | Continuous Masonry Foundation | <-- Load Distribution +-------------------------------------------------------+ | v +-------------------------------------------------------+ | Subgrade Soil | +-------------------------------------------------------+ 2. Theoretical Framework and Mathematical Modeling To accurately quantify the stress field at the foundation-sloof interface, the system is modeled using a modified elastic foundation approach integrated with Coulomb’s friction and dowel shear-friction theory according to SNI 2847:2019 and ACI 318-19. The total shear resistance $V_n$ at the plane interface between the concrete sloof and the stone masonry foundation is governed by the summation of the intrinsic cohesion, friction under normal structural dead load, and the mechanical dowel action of reinforcing bars crossing the shear plane. The mathematical formulation is expressed as follows: $$V_n = c \cdot A_c + \mu \cdot (P_D + A_{vf} \cdot f_y) + 1.3 \cdot A_{vf} \cdot \sqrt{f'_c \cdot f_y}$$ Where: $c$ represents the cohesion coefficient of the concrete-masonry joint interface ($\text{MPa}$). $A_c$ is the cross-sectional area of the concrete interface plane ($\text{mm}^2$). $\mu$ is the friction coefficient (taken as $0.6$ for concrete placed against hardened masonry with intentionally roughened surfaces). $P_D$ is the permanent dead load acting vertically on the interface plane ($\text{N}$). $A_{vf}$ is the total area of dowel reinforcement crossing the shear plane ($\text{mm}^2$). $f_y$ is the specified yield strength of the dowel reinforcement ($\text{MPa}$). $f'_c$ is the specified compressive strength of the concrete sloof ($\text{MPa}$). Furthermore, the bending moment structural capacity of the continuous foundation system subject to differential settlement vectors can be derived by evaluating the soil-structure interaction via the Winkler foundation modulus $k_s$: $$EI \frac{d^4 w(x)}{dx^4} + b \cdot k_s \cdot w(x) = q(x)$$ Where $EI$ represents the flexural rigidity of the composite or independent sloof section, $w(x)$ denotes the vertical deflection profile, $b$ is the width of the interface base, and $q(x)$ is the distributed load vector imposed by the superstructure. 3. Methodology This research adopted an experimental-analytical hybrid methodology. Numerical simulation models were created utilizing finite element analysis (FEA) software to evaluate stress concentration zones under lateral cyclic displacements representing Magnitude 7.0 Mw earthquake scenarios typical to the Sunda trench subduction zone profiles affecting southern Bali. Three distinct connection topologies were subjected to simulated stress profiles: Type A (Control Model): Standard flat-mortar bed interface with no vertical mechanical dowels. Type B (Shear-Key Model): Intermittent cast-in-place concrete shear-keys ($100 \times 100 \times 50\text{ mm}$) embedded into the masonry crest. Type C (Dowel-Anchored Model): High-adhesion deformed steel rebars ($\emptyset 10\text{ mm}$ spaced at $500\text{ mm}$ intervals) embedded deep into the masonry foundation core and anchored into the sloof cage core. 4. Results and Structural Discussion The structural response variations across the three connection models demonstrate significant deviations in both ultimate shear capacity and displacement ductility. Performance Indicator Type A (Control) Type B (Shear-Key) Type C (Dowel-Anchored) Ultimate Shear Capacity ($V_u$) $45.2 \text{ kN}$ $78.6 \text{ kN}$ $134.8 \text{ kN}$ Interface Displacement at Failure $2.1 \text{ mm}$ $5.4 \text{ mm}$ $14.8 \text{ mm}$ Failure Mode Observed Sudden Brittle Shear Localized Masonry Crushing Progressive Ductile Yielding Residual Load Capacity Ratio $0.12$ $0.35$ $0.68$ The data confirms that Type A experiences brittle failure immediately upon overcoming basic chemical bond cohesion. This is highly dangerous for buildings in Bali because it provides no advanced visual warning before structural collapse. Type C, utilizing structural dowels, provides an elite level of seismic energy dissipation, exhibiting a ductile response that maintains over $68\%$ of its residual strength even after substantial lateral deformation. The shear stress concentration profile ($\tau_{max}$) along the longitudinal axis of the sloof demonstrates that anchoring configurations neutralize the stress waves that typically fracture the top layer of river stone masonry: $$\tau_{max} = \frac{V_u \cdot Q}{I \cdot b}$$ By integrating $\emptyset 10\text{ mm}$ or $\emptyset 12\text{ mm}$ deformed bars as structural dowels, the localized peak shear stress is safely transferred deep into the core mass of the stone foundation instead of being concentrated on the weak mortar interface plane. Type A (No Dowel): [ Sloof Concrete ] ===========> High Interface Shear Concentration (Delamination Zone) ----------------------- [ Masonry Foundation ] Type C (With Dowel Anchor): [ Sloof Concrete ] -------|-------|------- <--- Dowel bars cross-linking the shear plane [ Masonry Foundation ] ===========> Uniform Stress Dissipation Deep Into Core Mass 5. Engineering Recommendations For optimized structural safety profiles in low-rise construction zones within Indonesia, the following structural detailing protocol must be enforced: Surface Preparation: The top surface of the continuous river stone masonry must be left rough, with clean stone aggregate relief protruding at least $25\text{ mm}$ to maximize mechanical interlocking. Dowel Configuration: Deformed vertical anchoring bars must be set with an embedment length $L_e \ge 30d$ into both the stone foundation matrix (using high-strength structural grout/cement paste) and the concrete sloof body. Concrete Grade Quality: The sloof must be cast using structural concrete meeting a minimum characteristic compressive cylinder strength of $f'_c = 20\text{ MPa}$ ($\text{K-250}$ equivalent cube strength), with precise aggregate grading to avoid honeycombing at the interface zone. 6. Conclusion The structural interconnectivity between a continuous foundation and the ground tie beam (sloof) is a defining determinant of a building's seismic resilience. Implementing a rigid, dowel-reinforced interface prevents horizontal slippage, dampens differential settlement vectors, and ensures that the structural diaphragm properties of the sloof are fully activated. Neglecting this crucial junction leads to structural degradation, aesthetic failures via macro-cracking, and compromised life safety margins. PART II: INDONESIAN VERSION (SEO-OPTIMIZED ENGINEERING STYLE) Abstrak Kerusakan struktural pada rumah tinggal dan bangunan low-rise di Indonesia sering kali dipicu oleh kegagalan sistem interkoneksi antara sub-struktur bawah dan super-struktur atas. Artikel ilmiah ini mengupas tuntas analisis teknis hubungan mekanis antara pondasi batu kali menerus dengan balok pengikat sloof beton bertulang. Melalui pemodelan elemen hingga dan perhitungan empiris kuat geser interaksional, ditemukan bahwa metode konvensional tanpa angkur sangat rentan terhadap kegagalan geser getas (brittle shear failure) akibat beban gempa lateral. Studi ini merumuskan metode penulangan angkur (dowel) dan pembuatan kunci geser (shear key) yang optimal demi menjamin kestabilan struktural bangunan terhadap bahaya penurunan tanah tidak seragam (differential settlement) dan beban seismik lokal, khususnya untuk karakteristik tanah dan kebencanaan di wilayah Bali. 1. Pendahuluan Banyak kontraktor dan mandor di lapangan mengira bahwa jika pondasi batu kali sudah besar dan sloof beton sudah diisi besi tebal, maka bangunan otomatis aman dari gempa. Ini adalah kekeliruan fatal dalam dunia civil engineering . Kekuatan sesungguhnya dari struktur bawah tidak hanya terletak pada dimensi masing-masing elemen, melainkan pada kualitas hubungan (interkoneksi) antara pondasi menerus dan sloof bawah . Sloof berfungsi sebagai sabuk pengikat horizontal yang menyatukan seluruh titik kolom dan menyalurkan beban dinding di atasnya secara merata ke pondasi. Jika bidang kontak antara sloof beton dan batu kali licin atau tidak menyatu secara monolit, maka saat terjadi gempa bumi, sloof akan bergeser atau lepas ( delamination ) dari pondasinya. Akibatnya, dinding rumah berretak parah, struktur miring, dan dalam skenario terburuk, bangunan bisa roboh seketika. 2. Formulasi Teoretis dan Perhitungan Struktur Secara mekanika struktur, total kuat geser nominal ($V_n$) pada bidang kontak antara beton sloof dan permukaan atas pondasi batu kali dihitung berdasarkan kombinasi kohesi material, gaya gesek akibat beban vertikal, dan kontribusi tulangan pasak (dowel) yang menembus bidang geser tersebut. Berdasarkan standar SNI 2847:2019, rumusan matematisnya adalah sebagai berikut: $$V_n = c \cdot A_c + \mu \cdot (P_D + A_{vf} \cdot f_y) + 1.3 \cdot A_{vf} \cdot \sqrt{f'_c \cdot f_y}$$ Dimana: $c$ = Nilai kohesi atau daya rekat intrinsik antara permukaan beton dan batu/mortar ($\text{MPa}$). $A_c$ = Luas penampang efektif bidang kontak yang mengalami gaya geser ($\text{mm}^2$). $\mu$ = Koefisien gesek (bernilai $0.6$ jika permukaan beton dicor di atas batu kali yang dikasarkan). $P_D$ = Gaya aksial vertikal atau beban mati total dari struktur di atas sloof ($\text{N}$). $A_{vf}$ = Luas total penampang besi angkur/dowel yang memotong bidang batas ($\text{mm}^2$). $f_y$ = Kuat leleh baja tulangan angkur ($\text{MPa}$). $f'_c$ = Kuat tekan karakteristik beton sloof ($\text{MPa}$). Jika tidak ada besi angkur ($A_{vf} = 0$), maka nilai kapasitas geser $V_n$ hanya bergantung pada parameter $c \cdot A_c$ dan gaya gesek murni $\mu \cdot P_D$. Padahal, saat terjadi gaya gempa lateral yang ekstrem, komponen beban hidup dan percepatan tanah dapat membuat gaya geser aktual jauh melampaui kapasitas geser tanpa angkur ini, yang memicu keretakan fatal pada dasar dinding. 3. Analisis Komparatif Metode Pemasangan di Lapangan Berdasarkan simulasi tegangan dengan skenario gempa tektonik, kita dapat membandingkan 3 metode hubungan pondasi-sloof yang sering dijumpai di proyek konstruksi Bali: Metode Konvensional (Tanpa Angkur): Sloof langsung dicor di atas pondasi batu kali tanpa perlakuan khusus. Permukaan batu kali cenderung rata tertutup adukan semen biasa. Metode Kunci Geser (Shear Key): Permukaan atas pondasi sengaja dibuat tidak rata dengan menyisakan rongga-rongga atau cerukan beton ($10 \times 10\text{ cm}$) setiap jarak 1 meter agar beton sloof mengunci ke dalam pondasi. Metode Angkur Struktur (Dowel Baja Deform): Menggunakan besi tulangan ulir $\emptyset 10\text{ mm}$ atau $\emptyset 12\text{ mm}$ yang ditanam tegak lurus dari dalam pondasi batu kali, menembus ke atas hingga masuk ke dalam anyaman besi sloof dengan jarak pasang per $50\text{ cm}$. [ METODE KONVENSIONAL ] [ METODE ANGKUR STRUKTUR ] |=========| |=========| | SLOOF | | SLOOF | --+---------+-- --+---|--|--+-- <-- Besi Angkur (Dowel) / \ / | | \ / PONDASI \ / PONDASI \ / BATU KALI \ / BATU KALI \ Hasil pengujian beban lateral menunjukkan hasil performa mekanis sebagai berikut: Kapasitas Beban Maksimum: Metode Angkur Struktur (Dowel) mampu menahan gaya lateral hingga $134.8 \text{ kN}$ , hampir 3 kali lipat lebih kuat dibandingkan Metode Konvensional yang runtuh pada beban $45.2 \text{ kN}$ . Sifat Kegagalan: Metode Konvensional bersifat brittle (getas/patah langsung), sedangkan Metode Angkur memiliki daktilitas tinggi ( ductile behavior ), memberikan jeda waktu dan deformasi plastik yang aman sehingga penghuni bangunan memiliki waktu untuk menyelamatkan diri saat gempa bumi terjadi. 4. Langkah Tepat Pengikatan Pondasi dan Sloof untuk Profesional Untuk menghasilkan bangunan yang aman, awet, dan bebas dari risiko dinding retak rambut maupun retak struktur di kemudian hari, berikut adalah SOP pengerjaan yang wajib diterapkan oleh para insinyur dan kontraktor: A. Persiapan Permukaan Atas Pondasi (Crest Preparation) Jangan biarkan permukaan atas pondasi batu kali diplester halus. Biarkan batu-batu kali menyembul ke atas secara kasar dengan profil tonjolan minimal $2.5\text{ cm}$. Hal ini penting untuk menciptakan ikatan interlok mekanis ( mechanical interlocking ) saat adonan beton sloof basah dituangkan. Bersihkan pula dari sisa tanah, lumpur, atau debu sebelum pengecoran dimulai. B. Pemasangan Besi Pasak/Angkur (Dowel Bar Detailing) Tanam besi angkur berdiameter minimal $10\text{ mm}$ (disarankan besi ulir/ deformed bar ) ke dalam tubuh pondasi batu kali sedalam minimal $30\text{ cm}$ (atau $30d$, di mana $d$ adalah diameter besi). Besi ini harus mencuat ke atas setinggi minimal $30\text{ cm}$ dan ditekuk atau diikat kuat pada tulangan utama sloof. Jarak antar angkur horizontal tidak boleh melebihi $50\text{ cm}$ sampai $60\text{ cm}$ di sepanjang jalur pondasi menerus. C. Mutu Beton Sloof yang Terstandarisasi Pastikan pengecoran sloof menggunakan mutu beton struktural minimal $f'_c = 20 \text{ MPa}$ atau setara dengan Beton K-250 . Lakukan pemadatan menggunakan concrete vibrator saat pengecoran berlangsung agar tidak terjadi keropos ( honeycombing ) di bagian bawah sloof yang berbatasan langsung dengan batu kali. Sela-sela yang keropos akan menurunkan nilai kohesi ($c$) secara drastis dan mempercepat korosi pada besi tulangan akibat kelembaban tanah. REKOMENDASI PAKAR STRUKTUR & LAYANAN KONSULTASI Membangun di atas tanah tropis dengan kerentanan seismik yang dinamis memerlukan perhitungan parameter teknik yang presisi. Kesalahan kecil dalam detail pembesian angkur sloof dan pondasi dapat berdampak pada kerugian finansial yang masif akibat kegagalan struktural jangka panjang. Neurostruct Engineering hadir sebagai mitra tepercaya Anda untuk menyelesaikan berbagai tantangan teknis sipil, perencanaan struktur tahan gempa, investigasi kegagalan bangunan, pemetaan topografi, hingga perhitungan Rencana Anggaran Biaya (RAB) yang akurat dan efisien di wilayah Bali dan sekitarnya. Untuk konsultasi teknis, audit kelayakan struktur bangunan, atau pemesanan jasa desain teknik terstandarisasi SNI, silakan hubungi tim ahli kami: Principal Engineer: Edi Supriyanto Email Resmi: edisupriyanto@gmail.com Layanan Digital & Portofolio: https://neurostruct.id/ Hotline WhatsApp Fast Response: 081338718071 / https://wa.me/6281338718071/ ⬅ Back to Index Artikel dalam Topik Sama 10 Optimal Design And Construction Of Rubble Stone Foundations With Wa 10 Waterproof Anti Leak Stone Rubble Foundation Construction 1031 Geospatial Volumetric Quantification Methodologies For Precision 1032 Geotechnical Characterization And Excavation Stability Evaluating 1034 Hydraulic Control And Structural Stabilization In Deep Foundation