A review and comparison of design methods for raft substructures on expansive soils

Teodosio, Bertrand; Baduge, Shanaka Kristombu; Mendis, Priyan

doi:10.1016/j.jobe.2021.102737

Cited by 10 publications

(11 citation statements)

References 48 publications

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“…The magnitude of area load, p, and the line load along the perimeter due to superstructures, q, can be critical in the design of a residential footing system (Teodosio et al 2021b). In the centre heave scenario in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Several design methodologies for residential footing systems founded on reactive soils have been developed over the past decades (Teodosio 2020;Teodosio et al 2021b). The Building Research Advisory Board (1968) proposed the BRAB Method, which is a comparatively simplistic procedure compared to other approaches.…”

Section: Introductionmentioning

confidence: 99%

“…These methods were used to propose a design method based on parametric simulations presented in Australian Standards (AS) 2870-2011(Standards Australia 2011Payne and Cameron 2014). The methodologies of the Walsh Method, Mitchell Method, and AS 2870-2011 Method tend to compute less conservative D of residential footing systems founded on reactive soils (Abdelmalak 2007;Teodosio et al 2021b). The AS 2870-2011 Method assumes commonly applied loads, p and q, on footing systems, where the values of p and q cannot be varied in the design process.…”

Section: Introductionmentioning

confidence: 99%

“…This method predicts median Fig. 1 Schematic representation of the interaction between reactive soils and a residential footing system when a shrinking (known as centre heaving) and b swelling (known as edge heaving) due to the difference in soil moisture of the covered and uncovered grounds values of calculated D when compared to other design approaches (Teodosio et al 2021b). However, the application of this method may be limited due to its empirical nature.…”

Section: Introductionmentioning

confidence: 99%

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Prediction of Residential Slab Foundation Movement Through a Finite Element-Based Deep Learning Algorithm

et al. 2022

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Deep learning networks were employed to predict the maximum differential deflection of stiffened and waffle rafts due to reactive soil movements, Δmax. Four deep learning networks were used to predict Δmax, these are (1) stiffened rafts on shrinking soil, (2) stiffened rafts on swelling soil, (3) waffle rafts on shrinking soil, and (4) waffle rafts on swelling soil. The deep learning models were used to create design lines, which showed that both soil and structural features strongly influence the stiffened rafts. In contrast, waffle rafts showed a strong dependence on soil features in shrinking soils and beam depth in swelling soils. This demonstrates that the finite element-based deep learning networks captured the effect of the embedment of the beams. The results of the deep learning models led to non-linear design curves, which are disparate from the suggested standard Australian design. These results suggest that increasing the value of beam depth can have a positive or negative impact on the global residential slab depending on the type of substructure and whether the founding reactive soil is shrinking or swelling. Global sensitivity analyses of the deep learning models showed that for stiffened rafts on shrinking soil, the slab length, slab width and active depth zone of reactive soil had the most significant influence on Δmax, whilst for stiffened rafts on swelling soil, the primary drivers are ground movement, beam depth, and slab width. The prediction of Δmax for waffle rafts on shrinking soil was driven by the surface characteristic and mound movements, and the active depth zone, whilst waffle rafts on swelling soil was driven by the beam depth. Overall, the finite element-based deep learning showed the capacity to estimate Δmax in both shrinking and swelling design scenarios for different types of residential footing systems to further understand the characteristic behaviour of shallow residential slab foundations on reactive soils leading to improved designs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Prediction of Residential Slab Foundation Movement Through a Finite Element-Based Deep Learning Algorithm

et al. 2022

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“…Reactive soils are clayey footings, which undergo a significant change in volume due to seasonal soil water content changes. These soils experience swelling when the water level increases and shrinking when the water level decreases [16,17]. The difference in soil water level between the uncovered ground, where evaporation, transpiration and precipitation take place, and the covered ground, where impermeable footings are constructed, causes differential ground movement (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Multi-Criteria Analysis of a Developed Prefabricated Footing System on Reactive Soil Foundation

Teodosio

Bonacci²,

Seo

et al. 2021

Energies

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The need for advancements in residential construction and the hazard induced by the shrink–swell reactive soil movement prompted the development of the prefabricated footing system of this study, which was assessed and compared to a conventional waffle raft using a multi-criteria analysis. The assessment evaluates the structural performance, cost efficiency, and sustainability using finite element modelling, life cycle cost analysis, and life cycle assessment, respectively. The structural performance of the developed prefabricated system was found to have reduced the deformation and cracking by approximately 40%. However, the cost, GHG emission, and embodied energy were higher in the prefabricated footing system due to the greater required amount of concrete and steel than that of the waffle raft. The cost difference between the two systems can be reduced to as low as 6% when prefabricated systems were installed in a highly reactive sites with large floor areas. The life cycle assessment further observed that the prefabricated footing systems consume up to 21% more energy and up to 18% more GHG emissions. These can significantly be compensated by reusing the developed prefabricated footing system, decreasing the GHG emission and energy consumption by 75–77% and 55–59% with respect to that of the waffle raft.

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Design of prefabricated footing connection using a coupled hydro‐mechanical finite element model

Teodosio

Baduge

Mendis

2021

Structural Concrete

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The use of prefabricated systems can alleviate the inadequate housing and skilled workers in most developed countries by expediting required construction time, reducing material wastage, decreasing the effect of weather impacts, minimizing unexpected costs, skilled labor dependence, and construction hazards. The full potential of prefabricated construction is yet to be realized in part due to most advancements being focused on its superstructure. The development of prefabricated substructures for lightweight buildings needs to consider the susceptibility to damage induced by the shrink‐swell movement of expansive soils causing significant global financial losses. Prefabricated substructures should have robust connections in discontinued regions to transfer forces and moments. Due to these issues, the aim of this study is to develop a connection for prefabricated raft substructures of single‐detached dwellings on expansive soils using a combined soil‐structure contact analysis and strut‐and‐tie model approach. The developed substructure system was validated using experiments and further investigated through numerical simulations. The developed prefabricated connection was observed to have satisfactory performance, potentially overcoming most construction limitations of conventional monolithic cast‐in‐place raft substructures, such as faster, safer, and more sustainable construction, while providing comparable strength and serviceability.

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A review and comparison of design methods for raft substructures on expansive soils

Cited by 10 publications

References 48 publications

Prediction of Residential Slab Foundation Movement Through a Finite Element-Based Deep Learning Algorithm

Prediction of Residential Slab Foundation Movement Through a Finite Element-Based Deep Learning Algorithm

Multi-Criteria Analysis of a Developed Prefabricated Footing System on Reactive Soil Foundation

Design of prefabricated footing connection using a coupled hydro‐mechanical finite element model

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