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1
Content available Bearing capacity of E-shaped footing on layered sand
EN
Purpose: The purpose of this study is to estimate the ultimate bearing capacity of the E-shaped footing resting on two layered sand using finite element method. The solution was implemented using ABACUS software. Design/methodology/approach: The numerical study of the ultimate bearing capacity of the E-shaped footing resting on layered sand and subjected to vertical load was carried out using finite element analysis. The layered sand was having an upper layer of loose sand of thickness H and lower layer was considered as dense sand of infinite depth. The various parameters varied were the friction angle of the upper (30° to 34°) and lower (42° to 46°) layer of sand as well as the thickness (0.5B, 2B and 4B) of the upper sand layer. Findings: The results reveal that the dimensionless ultimate bearing capacity was found to decrease with the increased in the H/B ratio for all combinations of parameters. The dimensionless ultimate bearing capacity was maximum for the upper loose sand friction angle of 34° and lower dense sand friction angle of 46°. The results further reveal that the dimensionless bearing capacity of the E-shaped footing was higher in comparison to the dimensionless bearing capacity of the square footing on layered sand (loose over dense). The improvement in the ultimate bearing capacity for the E-shaped footing was observed in the range of 109.35% to 152.24%, 0.44% to 7.63% and 0.63% to 18.97% corresponding to H/B ratio of 0.5, 2 and 4 respectively. The lowest percentage improvement in the dimensionless bearing capacity for the E-shaped footing on layered sand was 0.44 % at a H/B = 2 whereas the highest improvement was 152.24 % at a H/B = 0.5. Change of footing shape from square to E-shaped, the failure mechanism changes from general shear to local shear failure. Research limitations/implications: The results presented in this paper were based on the numerical study conducted on E-shaped footing made out of a square footing of size 1.5 m x 1.5 m. However, further validation of the results presented in this paper, is recommended using experimental study conducted on similar size E-shaped footing. Practical implications: The proposed numerical study can be useful for the architects designing similar types of super structures requiring similar shaped footings. Originality/value: No numerical study on E-shaped footing resting on layered sand (loose over dense) were conducted so far. Hence, an attempt was made in this article to estimate the bearing capacity of these footings.
EN
Purpose: The purpose of this study is to investigate the ultimate bearing capacity of the embedded and skirted E-shaped footing resting on two layered sand using finite element method. The analysis was carried out by using ABACUS software. Design/methodology/approach: The numerical study of the ultimate bearing capacity of the embedded and skirted E-shaped footing resting on layered sand and subjected to vertical load was carried out using finite element analysis. The layered sand was having an upper layer of loose sand of thickness H and lower layer was considered as dense sand of infinite depth. The various parameters varied were the friction angle of the upper (30° to 34°) and lower (42° to 46°) layer of sand, the skirt depth (0B, 0.25B, 0.5B and 1B), the embedment depth (0B, 0.25B, 0.5B and 1B) and the thickness (0.5B, 2B and 4B) of the upper sand layer, where B is the width of the square footing. Findings: The ultimate bearing capacity was higher for the skirted E-shaped footing followed by embedded E-shaped footing and unskirted E-shaped footing in this order for all combinations of variables studied. The improvement in the ultimate bearing capacity for the skirted E-shaped footing in comparison to the embedded E-shaped footing was in the range of 0.31 % to 61.13 %, 30.5 % to 146.31 % and 73.26 % to 282.38% corresponding to H/B ratios of 0.5, 2.0 and 4.0 respectively. The highest increase (283.38 %) was observed at φ1 =30° and φ2 =46° corresponding to H/B and Ds/B ratio of 4.0 and 1.0 respectively while the increase was lowest (0.31 %) at φ1 =34° and φ2 =46° at H/B ratio of 0.5 and Ds/B ratio of 0.5. For the skirted E-shaped footing, the lateral spread was more as in comparison to the embedded E-shaped footing. The bearing capacity of the skirted footing was equal the sum of bearing capacity of the surface footing, the skin resistance developed around the skirt surfaces and tip resistance of the skirt with coefficient of determination as 0.8739. The highest displacement was found below the unskirted and embedded E-shaped footing, and at the skirt tip in the case of the skirted E-shaped footing. Further, the displacement contours generated supports the observations of the multi-edge embedded and skirted footings regarding the ultimate bearing capacity on layered sands. Research limitations/implications: The results presented in this paper were based on the numerical study conducted on E shaped footing made from a square footing of size 1.5 m x 1.5 m. However, further validation of the results presented in this paper, is recommended using experimental study conducted on similar size E shaped footing. Practical implications: The proposed numerical study can be an advantage for the architects designing similar types of super structures requiring similar shaped footings. Originality/value: No numerical study on embedded and skirted E shaped footing resting on layered sand (loose over dense) were conducted so far. Hence, an attempt was made in this article to estimate the bearing capacity of the same footings.
PL
Oceniono wpływ rodzaju materiału przęseł na szerokość rdzenia sprężystego pod fundamentem przyczółka. Rozpatrywano mosty betonowe, stalowe i zespolone. Analizę podanych rozwiązań przeprowadzono, przyjmując różne wartości długości mostu L, różnicy temperatury ΔT szerokości fundamentu B i odsadzek, wysokości nasypu za przyczółkiem H i wysokości gruntu od strony światła mostu h. Wyniki analizy umożliwiły określenie racjonalnej długości mostów zintegrowanych w zależności od rodzaju przęseł. Największy wpływ na szerokość rdzenia sprężystego c i jego położenie ma całkowita długość przęseł mostu L i różnica temperatury ΔT Mniejszy jest wpływ szerokości lundamentu B, wysokości nasypu H i grubości gruntu h od strony światła mostu.
EN
The impact of the type of span material on the elastic core width below the abutment footing is assessed. The study was done on concrete, steel and composite bridges. In the analysis of the proposed solutions various lengths L of bridges, temperature variations ΔT, widths of footing B and setoff, embankment height H behind the abutment and embankment height h on the side of bridge clearance were adopted. Based on the results of the analysis reasonable lengths of integral bridges depending on the type of spans can be defined. The most significant impact on width c and location of the elastic core is exerted by the overall length of bridge spans L and temperature change ΔT. Footing width B, embankment height H and thickness of soil layer h on the side of bridge clearance are of lesser importance.
PL
Podano wyniki obliczeń osiadania stóp i ław fundamentowych posadowionych bezpośrednio na najczęściej spotykanych w praktyce budowlanej gruntach, przy obciążeniu odpowiadającym nośności obliczeniowej podłoża. Stwierdzono, że obliczone osiadania mogą przekraczać osiadania graniczne w przypadku fundamentów o dużych wymiarach, przy występowaniu pod nimi piasków średnich, grubych i żwirów.
EN
The article attempts to determine whether the settlement of typical direct foundations (strip foundations and spot footings), situated on the most commonly encountered in practice soils, with a load corresponding with calculated bearing capacity of the ground, are compatible with norm requirements. The calculations have shown that they can exceed smax for the foundations with large dimensions, in case of non-cohesive soils beneath them: sand medium, coarse and gravel.
PL
Przedstawiono wyniki obliczeń osiadania podłoża warstwowego w konstrukcji nasypu drogowego, podloża gruntowego pod ławą oraz podłoża gruntowego pod stopą fundamentową. W obliczeniach zastosowano opracowane jednowymiarowe elementy wielopolowe, a uzyskane wartości porównano z rozwiązaniem uwzględniającym podłoże sprężyste Winklera.
EN
The results of subsidence calculations of layered subsoil for three comparative examples: road embankment, subsoil under the continuous footing and subsoil under the spot footing have been presented in the paper. In the calculations developed one-dimensional multi-area finite elements have been applied. Obtained results have been compared with the values as for the elastic Winkler's subsoil subsidence.
PL
W artykule przedstawiono metodę obliczeń nośności na przebicie żelbetowej stopy fundamentowej wg normy Eurokod 2 (EC2). Omówiono sposób wyznaczania krytycznego obwodu kontrolnego. Przedstawiono analizę wykorzystania nośności na przebicie w zależności od położenia obwodu kontrolnego. Wanalizie przeprowadzono obliczenia 1230 potencjalnych powierzchni przebicia.
EN
The paper presents method of calculation of punching shear strength of reinforced concrete footing according to Eurocode 2 (EC2). The article presents how to determine the critical perimeter. There is the analysis of the punching shear strength depending on the location critical perimeter. The analysis was carried out calculations for the 1230 potential surface damage.
PL
Porównano obliczeniowe nośności jednostkowe gruntów według Eurokodu 7 i dotychczasowej polskiej normy. Wykazano znaczne zróżnicowanie otrzymanych wyników w zależności od rodzaju fundamentu (ława lub stopa fundamentowa) oraz rodzaju gruntu (spoisty lub niespoisty).
EN
This paper contains the comparative analysis of the computational unit load capacity ground according to Eurocode 7 and current Polish standard. The comparison shows variety of results depending on the kind of foundation (concrete strip footing or spot footing) and the kind of the soil (cohesive and uncohesive).
PL
Przedstawiono procedurę obliczania stóp fundamentowych na przebicie zgodnie z Eurokodem 2. Wykazano istnienie znacznej różnicy pomiędzy poprzednimi przepisami (polskimi normami) i Eurokodem 2. Dodatkowo porównano wyniki badań eksperymentalnych z teoretycznymi. To porównanie wykazało niedoskonałość procedury obliczeniowej i to w kierunku niebezpiecznym.
EN
The paper presents a procedure for calculating the punching shear capacity of footings according to Eurocode 2. The significant differences between the previous approach and Eurocode 2 were highlighted, showing more precise of requirements. In addition, the provisions of Eurocode 2 were compared with the results of experimental research for footings. This comparison has shown the inadequacy of the calculation procedure in unsafe direction.
PL
Przedstawiono obliczanie sił wewnętrznych w przekrojach obliczeniowych stóp fundamentowych o podstawie piramidalnej przy działaniu mimośrodowego obciążenia. Stwierdzono, że w stopach fundamentowych o podstawie piramidalnej siły wewnętrzne są 30 ÷ 50% mniejsze niż w stopach o podstawie płaskiej.
RU
В cтaтьe дано определениe внутpeнниx yсилий в расчётных сечениях плитных фундаментов с пирамидальной подошвой при действии внецентренной нагрузки.
PL
Przeprowadzono analizę wpływu podatności stóp fundamentowych w niestężonych ramach wielokondygnacyjnych na wartości sił wewnętrznych ramy. Podano prostą metodę wyznaczenia sztywności stopy fundamentowej oraz rozwiązano przykład liczbowy.
EN
An analyse of influence of semi-rigid foundation bases on internal forces of multi-story unbraced frames has been presented. A simple method of rigidity determination of foundation base has been given and a numerical example has been solved.
PL
Przedstawiono procedurę oszacowań unoszenia stopy fundamentowej, spowodowanego zamarzaniem gruntu poniżej poziomu posadowienia.
EN
During the maintenance period of the building, the ground under foundation may freeze. The volume of the ground increases during freezing and there is also significant increase of its deformation module. The paper presents a simple estimation procedure for the prediction of foundation elevation caused by the ground freezing below the foundation level.
PL
Oceniono nośność i osiadania stóp fundamentowych posadowionych bezpośrednio na podłożu piaszczystym. Stwierdzono, że według obliczeń zgodnych z PN-81/B-03020 otrzymuje się zaniżone wartości nośności przy normowych wartościach kąta tarcia wewnętrznego.
EN
It was stated that in accordance with examined PN-81/B-03020 the results of calculation standard values of the angles of internal friction are lower than examined.
14
Content available remote Wymiarowanie ścianek kielicha stopy fundamentowej
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