Stress Distribution and Rib Reinforcement Design in Konstruksi Sarang Laba-Laba (KSLL) Foundations Using the Winkler Method
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Abstract
Previous studies on Konstruksi Sarang Laba-Laba (KSLL) foundations have primarily focused on bearing capacity and overall foundation performance, while limited attention has been given to soil–structure interaction, stress distribution, and reinforcement design of KSLL ribs using the Winkler method. This study investigates the stress distribution in KSLL foundation ribs and determines the corresponding reinforcement requirements under different subgrade conditions. A numerical modeling approach was employed using a structural analysis program to simulate KSLL foundations on three soil categories—soft, medium, and stiff soils—with three rib/column connector dimensions of 30 × 30 cm, 50 × 50 cm, and 80 × 80 cm. The analysis was based on the modulus of subgrade reaction (Ks) to represent Winkler-type foundation springs. The results show that Ks increases with soil stiffness, indicating stronger subgrade support in stiffer soils. Soft soil consistently produced the highest normal stress, shear stress, and settlement, followed by medium and stiff soils. The ratio of normal stress between soft and stiff soils ranged from 1.5 to 3.0, while the shear stress ratio ranged from 1.4 to 2.0 at support zones and 1.6 to 1.9 at span regions. The effect of column-size variation on normal stress was relatively limited, although larger column dimensions reduced shear stress at supports by improving force distribution. The required main reinforcement increased with normal stress, reaching 7–8 bars in soft soil, 6 bars in medium soil, and 5–6 bars in stiff soil. Shear reinforcement spacing decreased as shear demand increased, with minimum spacing of 110 mm in soft soil, 150 mm in medium soil, and 260 mm in stiff soil. These findings demonstrate the importance of incorporating soil–structure interaction, subgrade stiffness, and rib-specific reinforcement design in KSLL foundation analysis to achieve safer and more efficient shallow foundation design.
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License and Copyright
This work is licensed under a Creative Commons Attribution 4.0 International License.
Copyright (c): Akbar Kurnia, Andriani Andriani, Abdul Hakam (2026)
How to Cite
Kurnia, A., Andriani, A., & Hakam, A. (2026). Stress Distribution and Rib Reinforcement Design in Konstruksi Sarang Laba-Laba (KSLL) Foundations Using the Winkler Method. MOTIVECTION : Journal of Mechanical, Electrical and Industrial Engineering, 8(1), 35-50. https://doi.org/10.46574/motivection.v8i1.526
References
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[3] F. M. Wani, J. Vemuri, C. Rajaram, and D. V. Babu R., “Effect of soil structure interaction on the dynamic response of reinforced concrete structures,” Natural Hazards Research, vol. 2, no. 4, pp. 304–315, 2022, doi: 10.1016/j.nhres.2022.11.002
[4] D.-W. Chang, C.-W. Lu, Y.-J. Tu, and S.-H. Cheng, “Settlements and Subgrade Reactions of Surface Raft Foundations Subjected to Vertically Uniform Load,” Applied Sciences, vol. 12, no. 11, Art. no. 5484, 2022, doi: 10.3390/app12115484.
[5] S. Koltuk and S. Topçu, “Determination of Subgrade Reaction Modulus Considering the Relative Stiffnesses of Soil–Foundation Systems,” Applied Sciences, vol. 15, no. 9, Art. no. 4714, 2025, doi: 10.3390/app15094714.
[6] A. M. Ebid, K. C. Onyelowe, and M. Salah, “Load-Settlement Curve and Subgrade Reaction of Strip Footing on Bi-Layered Soil Using Constitutive FEM-AI Coupled Techniques,” Designs, vol. 6, no. 6, Art. no. 104, 2022, doi: 10.3390/designs6060104.
[7] M. H. Abu-Ali, B. El-Garhy, A. Boraey, W. S. Alrashed, M. El-Shami, H. Abdel-Daiem, and B. Alrefahi, “Behavior of Stiffened Rafts Resting on Expansive Soil and Subjected to Column Loads of Lightweight-Reinforced Concrete Structures,” Buildings, vol. 14, no. 3, Art. no. 588, 2024, doi: 10.3390/buildings14030588.
[8] S. A. M. Hejazi, A. Feyzpour, M. Khaje Khabaz, A. Eslami, M. Fouladgar, S. A. Eftekhari, and D. Toghraie, “Numerical investigation of rigidity and flexibility parameters effect on superstructure foundation behavior using three-dimensional finite element method,” Case Studies in Construction Materials, vol. 18, Art. no. e01867, 2023, doi: 10.1016/j.cscm.2023.e01867.
[9] P. D. Candra, A. Andriani, A. Hakam, and R. Apdeni, “Improvement of California Bearing Ratio (CBR) Value of Clay Soil in Limau Manis Area, Padang by Using Lime and Rice Husk Ash,” MOTIVECTION: Journal of Mechanical, Electrical and Industrial Engineering, vol. 6, no. 3, pp. 343–354, 2024, doi: 10.46574/motivection.v6i3.390.
[10] M. R. Riaz, H. Motoyama, and M. Hori, “Review of Soil-Structure Interaction Based on Continuum Mechanics Theory and Use of High Performance Computing,” Geosciences, vol. 11, no. 2, Art. no. 72, 2021, doi: 10.3390/geosciences11020072.
[11] A. Raj, S. Haldar, and S. Patra, “Subgrade Modulus Distribution and Load-Sharing in Piled Raft Foundations under V-H-M Loading,” Structures, vol. 74, Art. no. 108569, 2025, doi: 10.1016/j.istruc.2025.108569.
[12] P. Salari, N. H. Moghaddas, G. R. Lashkaripour, and M. Ghafoori, “Presenting new models to determine subgrade reaction modulus (Ks) for optimizing foundation calculations in coarse grained soils,” Revista de la Construcción, vol. 19, no. 2, pp. 235–243, 2020, doi: 10.7764/rdlc.19.2.235.
[13] B. Liu, J. Xue, B. M. Lehane, and Z.-Y. Yin, “Time-dependent Soil–Structure Interaction Analysis Using a Macro-Element Foundation Model,” Engineering Structures, vol. 308, Art. no. 118046, 2024, doi: 10.1016/j.engstruct.2024.118046.
[14] J. D. Wagh and A. N. Bambole, “Improved correlation of soil modulus with SPT N values,” Open Engineering, vol. 14, no. 1, Art. no. 20240046, 2024, doi: 10.1515/eng-2024-0046.
[15] D.-W. Chang, S.-H. Cheng, W.-C. Zheng, C.-Y. Tseng, and L. Ge, “Serviceability Performance of Piled Raft Foundations under Vertical Loads in Clayey and Sandy Soils,” Soils and Foundations, vol. 65, no. 4, Art. no. 101650, 2025, doi: 10.1016/j.sandf.2025.101650.
[16] S. Leppla, A. Norkus, M. Karbočius, and V. Gribniak, “Design and Numerical Analysis of a Combined Pile–Raft Foundation for a High-Rise in a Sensitive Urban Environment,” Buildings, vol. 15, no. 16, Art. no. 2933, 2025, doi: 10.3390/buildings15162933.
[17] A. Khosravifardshirazi, B. Tavana, A. A. Javadi, A. Johari, S. Gholzom, B. Khosravifardshirazi, and M. Akrami, “Role of the Subgrade Reaction Modulus in the Design of Foundations for Adjacent Buildings,” Buildings, vol. 14, no. 6, Art. no. 1804, 2024, doi: 10.3390/buildings14061804.
[18] J. D. Patrício, A. D. Gusmão, S. R. M. Ferreira, F. A. N. Silva, H. J. Kafshgarkolaei, A. C. Azevedo, and J. M. P. Q. Delgado, “Settlement Analysis of Concrete-Walled Buildings Using Soil–Structure Interactions and Finite Element Modeling,” Buildings, vol. 14, no. 3, Art. no. 746, 2024, doi: 10.3390/buildings14030746.
[19] B. Teodosio, P. L. P. Wasantha, E. Yaghoubi, M. Guerrieri, S. Fragomeni, and R. C. van Staden, “Environmental, Economic, and Serviceability Attributes of Residential Foundation Slabs: A Comparison between Waffle and Stiffened Rafts Using Multi-Output Deep Learning,” Journal of Building Engineering, vol. 80, Art. no. 107983, 2023, doi: 10.1016/j.jobe.2023.107983.
[20] R. Luo, Z. Li, B. Zhu, and Q. Yang, “Differential Settlements of Piled Raft Foundation: Numerical Simulations, Empirical Equations and Design Charts,” Journal of Building Engineering, vol. 111, Art. no. 113118, 2025, doi: 10.1016/j.jobe.2025.113118.
[21] B. Ateş and E. Şadoğlu, “Experimental and Numerical Investigation of Load Sharing Ratio for Piled Raft Foundation in Granular Soils,” KSCE Journal of Civil Engineering, vol. 26, no. 4, pp. 1662–1673, 2022, doi: 10.1007/s12205-022-1022-4.
[22] S. Leppla, A. Norkus, M. Karbočius, and V. Gribniak, “Design and Numerical Analysis of a Combined Pile–Raft Foundation for a High-Rise in a Sensitive Urban Environment,” Buildings, vol. 15, no. 16, Art. no. 2933, 2025, doi: 10.3390/buildings15162933.
[23] Z. Zhong et al., “The Influence of Soft Soil, Pile–Raft Foundation and Bamboo on the Bearing Characteristics of Reinforced Concrete (RC) Structure,” Buildings, vol. 15, no. 13, Art. no. 2302, 2025, doi: 10.3390/buildings15132302.
[24] C. Wallner, S. Stummer, and D. Schlicke, “Influence of Structural Stiffness Representation in Settlement Calculations and Practical Advice,” Buildings, vol. 15, no. 18, Art. no. 3270, 2025, doi: 10.3390/buildings15183270.
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[26] D. Chanda, R. Saha, S. Haldar, and D. Choudhury, “State-of-the-Art Review on Responses of Combined Piled Raft Foundation Subjected to Seismic Loads Using Static and Dynamic Approaches,” Soil Dynamics and Earthquake Engineering, vol. 169, Art. no. 107869, 2023, doi: 10.1016/j.soildyn.2023.107869.
[27] M. Xie, L. Yin, Z. Wang, F. Xu, X. Wu, and M. Xu, “Numerical Simulation and Analysis of Micropile-Raft Joint Jacking Technology for Rectifying Inclined Buildings Due to Uneven Settlement,” Buildings, vol. 15, no. 14, Art. no. 2485, 2025, doi: 10.3390/buildings15142485.
[28] H. Ahmad, “Numerical Study of Comparing Skirt Sandpile with Deep Cement Pile to Improve Load–Settlement Response of Circular Footing in Layered Soils: Centric and Eccentric Effects,” Heliyon, vol. 11, no. 2, Art. no. e41710, 2025, doi: 10.1016/j.heliyon.2025.e41710.
[29] T. Cui, Y. Shi, and F. Huang, “Experimental Study on the Uplift Correction of Raft Foundations in Saturated Silty Clay,” Buildings, vol. 15, no. 9, Art. no. 1415, 2025, doi: 10.3390/buildings15091415.
[30] B. A. Bapir, L. Abrahamczyk, P. Staubach, and T. Wichtmann, “Advanced Modeling of Nonlinear Soil-Structure Interaction Using the Clay Hypoplasticity Constitutive Model,” Results in Engineering, vol. 28, Art. no. 107954, 2025, doi: 10.1016/j.rineng.2025.107954.
[31] M. S. Kirçil and H. Ethemoglu, “Effect of Soil–Structure Interaction on the Damage Probability of Multistory RC Frame Buildings with Shallow Foundations,” Buildings, vol. 15, no. 4, Art. no. 624, 2025, doi: 10.3390/buildings15040624.