scholarly journals Comparison of Safety Margin of Shallow Foundation on Weathered Soil Layer According to Design Methods

2016 ◽  
Vol 17 (12) ◽  
pp. 55-64 ◽  
Author(s):  
Donggun Kim ◽  
Huiseok Hwang ◽  
Namjae Yoo
Keyword(s):  
Soil Layer ◽  
Safety Margin ◽  
Design Methods ◽  
Shallow Foundation ◽  
Weathered Soil

Seismic Behavior of Shear Wall-Frame Systems Considering Foundation Stiffness

2017 ◽  
Vol 17 (03) ◽  
pp. 1750041 ◽  
Author(s):  
Bo Di ◽  
Xueyi Fu
Keyword(s):  
Seismic Behavior ◽  
Safety Margin ◽  
Bending Moment ◽  
Shear Wall ◽  
Internal Force ◽  
Shallow Foundation ◽  
Frame Structure ◽  
Base Shear ◽  
Internal Forces ◽  
Frame Systems

In this paper, the influence of foundation stiffness on the seismic behavior of shear wall-frame systems was investigated. First, a basic differential equation was established to account for the interaction between the foundation and superstructure. By solving the equation, the influence of foundation stiffness on the lateral stiffness, inter-story drift, and internal force distribution of the superstructure at the elastic stage was elucidated. Subsequently, the concept and method for determining the range of foundation stiffness suitable for shear wall-frame systems were proposed. By taking a 12-story shear wall-frame structure built on a shallow foundation as an example, a parametric study was performed for various frame-to-wall relative stiffness ratios and foundation stiffnesses. The effect of shallow foundation stiffness on the base shear distribution and energy dissipation of the superstructure was clarified, with results compared with those of the fixed-base model. The analysis results indicated that the degeneration of foundation stiffness due to earthquake damages will result in significant redistribution of internal forces, namely, the internal forces of the walls decrease, while those of the frames increase. In particular, the shear-force and bending moment of the bottom frame columns rise drastically, which may greatly reduce the safety margin and should be considered in practical design.

Consolidation Settlement Analyses on a Composite Foundation System Combined with Walled and Columniform Soil Improvement

2010 ◽  
Vol 163-167 ◽  
pp. 2318-2327
Author(s):  
Wei Li ◽  
Fei Gao ◽  
He Huang ◽  
Haruyuki Yamamoto ◽  
Kinji Takeuchi
Keyword(s):  
Environmental Influence ◽  
Soil Layer ◽  
Soil Improvement ◽  
Differential Settlement ◽  
Composite Foundation ◽  
Shallow Foundation ◽  
Hydraulic Pressure ◽  
Raft Foundation ◽  
Consolidation Settlement ◽  
Geological Situation

To satisfy the geotechnical strength requirements and the serviceability requirements, types of foundation systems (such as shallow foundation, pile foundation and composite foundation) have been developed. Of course, the type of foundation system is determined by many factors such as ground condition, economy and environmental influence of construction. To cope with weak or compressible soils, the authors present a raft foundation system with walled and columniform soil improvement for multistory buildings, which is economical and environment-friendly. In this raft foundation system, different columniform soil improvements in size and depth are used, and the subgrade under the edge of the foundation is walled by soil improvement. It can effectively control differential settlement and prevent relative rising of the structure by adjusting the size and depth of columniform soil improvements according to the soil layer difference of geological situation under the building. We have performed series numerical analyses under two-dimensional plane strain condition to study the settlement behaviors of the composite foundation system, and its effects on controlling differential settlement and improving bearing capacity were verified for immediate condition. As a continuous research, consolidation settlement analyses are performed, the process of excess hydraulic pressure dispersion with time and the consolidation settlement development are studied in this paper.

scholarly journals Criteria for Preliminary Design of an Arched Steel Bridge on Shallow Foundation Under Soil Liquefaction Conditions

2017 ◽  
Vol 11 (1) ◽  
pp. 1170-1190 ◽  
Author(s):  
Isabella Vassilopoulou ◽  
Vasiliki Kaymenaki ◽  
Charis J. Gantes ◽  
George Bouckovalas
Keyword(s):  
Seismic Isolation ◽  
Design Method ◽  
Soil Layer ◽  
Soil Liquefaction ◽  
Shallow Foundation ◽  
Preliminary Design ◽  
Steel Bridge ◽  
Foundation Design ◽  
Deep Foundation ◽  
Liquefiable Soil

Introduction: The research is based on a proposed new foundation design method of bridges on liquefiable soil, consisting of using a shallow foundation and exploiting the liquefiable soil layer as natural seismic isolation, replacing thus the commonly employed deep foundation method. The use of this concept may be hindered by detrimental effects, such as large displacements and rotations that are expected to take place at the foundation of the structure during a strong seismic event, associated with permanent displacements due to the liquefaction phenomenon. Methods: The aim of the current study is to investigate the response of an arched steel bridge with two simply supported spans to displacements and rotations induced by soil liquefaction, delineate the acceptable limits of such ground movements that the bridge can sustain, avoiding the collapse of the superstructure, and define criteria for the preliminary design of the spread footing of the middle pier. To that effect, nonlinear analyses are performed, taking into account geometric and material nonlinearities. Displacements and rotations are imposed at the base of the pier and their amplitude is gradually increased until the first group of structural elements that reach failure is detected. Results and Conclusion: The values of displacements and rotations, for which failure occurs, specify the tolerable design limits. This is a first step towards investigating the feasibility of the above concept for bridges of this type.

scholarly journals Seismic codes based equivalent nonlinear and stochastic soil structure interaction analysis

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohamed Elhebib Guellil ◽  
Zamila Harichane ◽  
Erkan Çelebi
Keyword(s):  
Shear Modulus ◽  
Soil Structure ◽  
Soil Layer ◽  
Shallow Foundation ◽  
Soil Structure Interaction ◽  
Base Case ◽  
Eurocode 8 ◽  
Seismic Zone ◽  
Seismic Codes ◽  
Structure Interaction

AbstractThe aim of this study is to consider the effects of the variation of shear modulus ratio (G/G0) and damping ratio (ξ) of soil, obtained by a linear iterative method based on the design spectra of seismic codes, the soil environment in terms of uncertainties in shear modulus using Monte Carlo simulations and the foundation damping (ξf) of flexible base for analyses of the Soil-Structure Interaction (SSI) problems. A squat structure with circular shallow foundation resting on a soil layer over a homogeneous half-space is studied by using cone model and considering seismic zone effect on structural response. Firstly, after showing the effects of the correction of G and ξ on impedance functions and the responses of soil-foundation-structure system, a study is carried out to compare these effects to those of the modelling of uncertainties in shear modulus as random variations. Secondly, a comparative analysis on design response spectra and base shear forces was carried out for four seismic codes (Algerian Seismic Rules RPA99-2003, Eurocode 8–2004, International Building Code IBC-2015 and Indian Code IS-1893-2002) considering the three cases of SSI: SSI effects (initial G and ξ), nonlinear SSI (corrected G and ξ) and stochastic SSI (random G with COV = 20%) compared to the fixed base case. Results show that the correction of G and ξ, according to the equivalent nonlinear method in all the cases, leads to a remarkable decrease in peak responses but show a huge amount of reduction in the second study for IBC-2015 and IS-1893-2002 codes compared to the other codes.

scholarly journals Analysis of LRFD Resistance Factor for Shallow Foundation on Weathered Soil Ground

2015 ◽  
Vol 16 (6) ◽  
pp. 5-11
Author(s):  
Donggun Kim ◽  
Huntae Kim ◽  
Jeeweon Suh ◽  
Namjae Yoo
Keyword(s):  
Resistance Factor ◽  
Shallow Foundation ◽  
Weathered Soil

scholarly journals Pengujian Daya Dukung Tanah Pasir Dengan Perkuatan Geogrid

2021 ◽  
Vol 21 (01) ◽  
pp. 01-10
Author(s):  
Sarah alwiyah
Keyword(s):  
Tensile Strength ◽  
Bearing Capacity ◽  
Carrying Capacity ◽  
Soil Layer ◽  
Strong Support ◽  
Shallow Foundation ◽  
Soil Conditions ◽  
Layer By Layer ◽  
Synthetic Materials ◽  
Local Shear

[ID] Memperbaiki kondisi tanah merupakan salah satu penyelesaian masalah untuk meningkatkan daya dukung tanah dan memperkecil penurunan. Dengan berkembangnya teknologi dalam bidang geoteknik maka perkuatan tanah dapat dilakukan dengan memasang bahan sintetis seperti pemakaian geogrid. Geogrid mengandalkan kekuatan tarik yang tinggi dan kemuluran creep yang rendah, untuk kasus longsoran geogrid ditempatkan pada lapisan tanah, ditimbun, dan dipadatkan lapis demi lapis sehingga dapat menjaga menstabilkan tanah dengan mendistribusikannya menjadi kuat tarik. Tujuan penelitian ini untuk mengetahui pengaruh panjang geogrid terhadap penambahan daya dukung tanah pasir dan jumlah lapisan geogrid yang paling efisien untuk meningkatkan daya dukung tanah pasir terhadap beban pondasi dangkal menerus dengan perkuatan geogrid produk Tencate Geosynthetis asia Sdn Bhd (Malaysia) tipe GX 40/40 serta memiliki short term tensile strength 40 Kn/m.  Penilitian ini dilakukan dengan menggunakan model pondasi menerus yang diletakkan diatas kotak transparan yang diisi pasir dengan kondisi kepadatan relatif (Dr) 20%-40% dan diberi beban tegak lurus menggunakan dongkrak hidrolik. Dari hasil penelitian diketahui model keruntuhan yang terjadi adalah jenis Local shear dimana geogrid mengalami tarikan pada lokasi sekitar dibawah pondasi dengan lapisan teratas dan lapisan kedua mengalami tarikan yang lebih besar. Pada pengujian penempatan geogrid lapisan teratas terhadap pondasi menunjukkan bahwa penambahan kuat dukung terbesar diperoleh pada LG/B = 3. Pada pengujian penggunaan geogrid 2 lapis diperoleh jarak antara lembaran geogrid (s) menunjukkan bahwa penambahan kuat dukung terbesar diperoleh dengan jarak s = 0,4B. Pada pengujian jumlah pemasangan lapisan geogrid menunjukkan bahwa kuat dukung meningkat dari pemasangan 1 lapisan menjadi 2 lapisan dan penambahan jumlah selanjutnya tidak menunjukkan penambahan kuat dukung yang cukup segnifikan. [EN] Improving soil conditions is a solution to the problem to increase the bearing capacity of the soil and minimize subsidence. With the development of technology in the geotechnical field, soil strengthening can be done by installing synthetic materials such as the use of geogrids. Geogrids rely on high tensile strength and low creep elongation, in the case of landslides the geogrids are placed in the soil layer, stockpiled and compacted layer by layer so as to keep the soil stable by distributing it into tensile strength. This experimen was conducted to determine the effect of long a geogrid sand soil beraring capacity and the number of layers of geogrid, the most efficient way to increase soil bearing capacity of shallow foundation of sand on the continuous load with a geogrid reinforcement the product of Tencate Geosynthetis asia Sdn Bhd (Malaysia) type GX 40/40 and The mean ultimate tensile strength 40 Kn/m. The experiment was performed using continuous foundation model placed on a transparent box filled with sand with the relative density (Dr) 20%-40% and given a perpendicular load using hydrolic jack. From the results of research known mode of failure that occurs is a kind of Local shear where the geogrid experienced the pull on the location around under the foundation with the top layer and the second layer having the pull is greater. On testing the placement of the geogrid layer the top to the foundation showed that the addition of strong carrying capacity of the largest obtained in LG/B = 3. On testing the use of geogrid 2 layers obtained by the distance between the sheets geogrid (s) show that the addition of strong carrying capacity of the largest obtained by a distance s = 0,4 B. On testing the installation of a layer of geogrid showed that strong support increased from mounting 1 layer into 2 layers and the addition of a number of further does not show the addition of support strong enough segn.

The limits of human performance

2008 ◽  
Vol 44 ◽  
pp. 11-26 ◽  
Author(s):  
Ralph Beneke ◽  
Dieter Böning
Keyword(s):  
Human Performance ◽  
Safety Margin ◽  
Afferent Input ◽  
Metabolic Energy ◽  
Human Organism ◽  
Mechanical Resistance ◽  
As Doping ◽  
Gene And Protein Expression ◽  
Underlying Mechanisms ◽  
Biochemical Research

Human performance, defined by mechanical resistance and distance per time, includes human, task and environmental factors, all interrelated. It requires metabolic energy provided by anaerobic and aerobic metabolic energy sources. These sources have specific limitations in the capacity and rate to provide re-phosphorylation energy, which determines individual ratios of aerobic and anaerobic metabolic power and their sustainability. In healthy athletes, limits to provide and utilize metabolic energy are multifactorial, carefully matched and include a safety margin imposed in order to protect the integrity of the human organism under maximal effort. Perception of afferent input associated with effort leads to conscious or unconscious decisions to modulate or terminate performance; however, the underlying mechanisms of cerebral control are not fully understood. The idea to move borders of performance with the help of biochemicals is two millennia old. Biochemical findings resulted in highly effective substances widely used to increase performance in daily life, during preparation for sport events and during competition, but many of them must be considered as doping and therefore illegal. Supplements and food have ergogenic potential; however, numerous concepts are controversially discussed with respect to legality and particularly evidence in terms of usefulness and risks. The effect of evidence-based nutritional strategies on adaptations in terms of gene and protein expression that occur in skeletal muscle during and after exercise training sessions is widely unknown. Biochemical research is essential for better understanding of the basic mechanisms causing fatigue and the regulation of the dynamic adaptation to physical and mental training.

Social Recourses of the Population under Conditions of Losing Economic Stability

2015 ◽  
pp. 86-99 ◽  
Author(s):  
E. Avraamova ◽  
T. Maleva
Keyword(s):  
Economic Development ◽  
Social Policy ◽  
Social Development ◽  
Safety Margin ◽  
Economic Stability ◽  
Socio Economic Development ◽  
Development Stability ◽  
Made In

The loss of country’s socio-economic development stability puts on the agenda the problem of finding solutions contributing to the maintenance of Russian households’ welfare. The authors believe that these solutions lie in the broader area than applying various instruments of monetary support. The most effective solutions are related to the actualization of own resources of households that can act as a safety margin as well as a source of social development. The attempt to evaluate the households’ resource provision and highlight the significance of each resource enabling or creating barriers to the growth of households’ welfare is made in this article. On the basis of received conclusions social policy areas directed at preserving or enhancing the welfare are defined.

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