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1
Content available remote Analiza równania nośności granicznej prefabrykowanych pali wbijanych na podstawie wyników próbnych obciążeń statycznych
Stachecki Kamil, Meyer Zygmunt
Materiały Budowlane
|
2024
|
nr 5
1--4
PL
W artykule przeanalizowano wyniki próbnych obciążeń statycznych siedmiu pali prefabrykowanych wykonanych na budowie wiaduktu drogowego. Celem pracy było ustalenie zależności pomiędzy nośnością graniczną pala a jego długością oraz szerokością. Do osiągnięcia celu wykorzystano analizę statystyczną, co umożliwiło sfomułowanie równania, które mogło być następnie wykorzystane w obliczeniach. Określona zależność pozwala na obliczenie nośności granicznej pala w przypadku znanego oporu gruntu w poziomie podstawy. Przedstawiony w artykule przykład obliczeniowy opisuje zaimplementowanie rezultatów analizy do metody konwersji krzywej próbnego statycznego obciążenia pala.
EN
In this paper the results of static load tests of seven precast piles executed at the construction of the road overpass were analyzed. The aim of this work was to determine the relation between the ultimate pile bearing capacity, its length and width. Statistical analysis was used to achieve the goal, which made it possible to formulate an equation that could then be used in calculations. The determined dependence allows for the calculation of the ultimate pile bearing capacity on the basis of the known soil resistance at the level of pile base. The example of calculation presented in the paper describes implementation of the analysis results to the method of static load test curve conversion.
2
Content available remote Mechanical behavior of laminated bamboo-timber composite columns under axial compression
Chen Si, Wei Yang, Wang Gaofei, Zhao Kang, Ding Mingmin
Archives of Civil and Mechanical Engineering
|
2023
|
Vol. 23, no. 2
art. no. e72, 2023
EN
Bamboo is a fast-growing biobased building material with a high strength-to-weight ratio, and the combination of bamboo and wood provides an environmentally friendly alternative for building construction. A new type of laminated bamboo-timber composite column was proposed to improve the compressive performance of timber columns, which was expected to obtain better mechanical performance. Bamboo scrimber and Douglas fir were combined to form laminated bamboo-timber composite columns for the experimental study. Axial compression tests were carried out on 5 groups of 15 composite columns. The failure modes of the composite columns were assessed. The laws of axial displacement, lateral displacement, axial strain, ultimate bearing capacity and stiffness were analyzed. Finally, the bearing capacity of the composite columns was calculated by referring to the design specification for timber structures. The results indicated that the composite columns exhibited three failure characteristics. The ultimate bearing capacity and stiffness of the bamboo-timber composite columns increased with increasing amount of bamboo scrimber. The ultimate load of the bamboo-timber composite columns was increased by 23.0-94.6%, while the stiffness was increased by 9.1-38.4%. In addition, the bearing capacity of composite columns was calculated according to two standards. The experimental values of the bamboo-timber composite columns are in good agreement with the theoretical values, and the errors are within 8%.
3
Content available Optimization of heavy haul railway tunnel lining based on ultimate bearing capacity
Han Wei, Xiao Taoli, Shi Duanwen, Wang Yupeng
Archives of Civil Engineering
|
2022
|
Vol. 68, nr 4
493--511
EN
The optimization process of design parameters for composite lining of heavy haul railway tunnel is a key problem to be solved in tunnel engineering design. In order to put forward a better design scheme of composite lining for heavy haul railway tunnel, combined with field measurement and numerical simulation, the optimal working condition design is carried out by changing the thickness of shotcrete layer, the type of grid steel frame and the thickness of secondary lining. The influence of the above design parameters on the stress state of the composite lining is analyzed to obtain the optimal design parameters. Finally, the safety performance of the optimized lining is evaluated by the ultimate bearing capacity curve of the secondary lining section. The research shows that: 1) The optimal design parameters of the composite lining of the tunnel are the thickness of the shotcrete layer of 25 cm, the type of the grid steel frame of H180, the thickness of the secondary lining arch waist and the side wall of 40 cm and 35 cm respectively; 2) Different from the single-track heavy haul railway tunnel, the displacement value of the vault settlement of the double-track heavy haul railway tunnel is significantly greater than that of the inner convergence. Increasing the thickness of the shotcrete layer and changing the type of the grid steel frame have better effects on reducing the vault settlement, and have little effect on the inner convergence.
4
Content available remote Theoretical and numerical analysis on the ultimate bearing capacity of CFRP-confined CFSST stub columns
Tang Hongyuan, Chen Junlong, Yue Zhaoyang, Jia Yigang, Yuan Zhijun
Archives of Civil and Mechanical Engineering
|
2022
|
Vol. 22, no. 1
art. no. e26, 2022
EN
To analyze the ultimate bearing capacity of concrete-filled stainless steel tube (CFSST) stub columns confined by carbon fiber reinforced polymer (CFRP) under axial compression, this study conducted theoretical analysis, experimental research, and finite element simulation on CFRP-confined CFSST stub columns under axial compression. Through the theoretical analysis, using the continuous strength method and limit equilibrium method, a theoretical calculation model of the ultimate bearing capacity of the columns was established considering the evident strain hardening effect of stainless steel. In addition, through experimental research, it was found that the failure mode of CFRP-confined CFSST specimens is the typical CFRP fracture and that CFRP can effectively improve the axial compression performance of specimens and restrain the local buckling deformation of the stainless steel tube. Based on experimental research, a finite element model of the CFRP-confined CFSST stub column was established, and a parameter database for the finite element numerical analysis was established. By comparing the experimental results with the aforementioned parameter database, the theoretical model was verified to have a high accuracy in predicting the ultimate bearing capacity of CFRP-confined CFSST stub columns.
5
Content available remote Behavioural assessment on influence of adjacently placed strip footings at different embedment level
Ekbote Anupkumar G., Nainegali Lohitkumar, Rajhans Puja, Deepak M. S.
Architecture Civil Engineering Environment
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2022
|
Vol. 15, no. 4
93--103
EN
The footings laid in close proximity imposes a definite change in the behaviour of the adjacent footing, subsequently changing the behaviour of the nearby footings. The present study emphasises the behaviour of the nearby strip footings embedded at a different level by adopting the commercially available finite element analysis program, ABAQUS. The load-settlement behaviour, ultimate bearing capacity (UBC), and the failure patterns of adjacent strip footings are assessed by considering the Mohr-Coulomb failure criterion. The UBC is of the nearby footings (left and right) are estimated and represented in terms of interference factors (ξξL/ξξR) defined as the UBC of a footing in the presence of adjacent footing to that of same considered for equivalent isolated footing. The results reveal that a significant influence of the adjacent footing is experienced when the spacing between the footings (S/B) is lesser, and they behave as the single footing of greater width at S/B = 0.25 irrespective of the level of embedment depth. Furthermore, the influence of interference increases with the increase in the embedment depth of adjacent footing. It is found that the ξξL is significantly more for a lower level of embedment depth, and the same increases with an increase in the embedment depth of the right footing but on the contrary ξξR decreases. The increase in the peak interference factor, ξξL-max for DL/B = 0.5 is 2.1% and 4.2% when DR/B = 0.75 and DR/B = 1.0, respectively.
6
Content available Behaviour of eccentrically inclined loaded rectangular foundation on reinforced sand
Gupta Sujata, Mital Anupam
Studia Geotechnica et Mechanica
|
2021
|
Vol. 43, nr 2
74--89
EN
This study presents the behaviour of model footing resting over unreinforced and reinforced sand bed under different loading conditions carried out experimentally. The parameters investigated in this study includes the number of reinforced layers (N = 0, 1, 2, 3, 4), embedment ratio (Df/B = 0, 0.5, 1.0), eccentric and inclined ratio (e/L, e/B = 0, 0.05, 0.10, 0.15) and (a = 0°, 7°, 14°). The test sand was reinforced with bi-axial geogrid (Bx20/20). The test results show that the ultimate bearing capacities decrease with axial eccentricity and inclination of applied loads. The test results also show that the depth of model footing increase zero to B (B = width of model footing), an increase of ultimate bearing capacity (UBC) approximated at 93%. Similarly, the multi-layered geogrid reinforced sand (N = 0 to 4) increases the UBC by about 75%. The bearing capacity ratio (BCR) of the model footing increases with an increasing load eccentricity to the core boundary of footing; if the load eccentricities increase continuity, the BCR decreases. The tilt of the model footing is increased by increasing the eccentricity and decreases with increasing the number of reinforcing layers.
7
Content available Experimental and theoretical research on large-diameter rock-socketed pile embedded depth
Li Yanfeng, Zhao Jihe, Xiong Ying, Wang Qinghe
Archives of Civil Engineering
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2021
|
Vol. 67, nr 2
537--550
EN
A theoretical formula for large-diameter rock-socket depth is developed to support pail embedding in a large bridge pile foundation project. There is a horizontal additional stress concentration at the place where the soil around the rock-socketed pile meets the soil layer under the horizontal load. When the rock-socketed tip stress and bending moment of the pile are relatively small, the pile shows favourable embedment effect and the pile foundation can be considered safe. The function curve of soil resistance around the pile under the action of horizontal force was obtained by finite element analysis. The force characteristics reveal the depth of the largediameter rock-socketed pile under the horizontal load. As the rock-socketed pile rotates under the action of horizontal force, the rock mass resistance around the pile changes according to the cosine. The distribution of pileside soil resistance is proportional to the displacement and distributed according to the sine. A comprehensive correction coefficient of pile shaft resistance β is introduced to deduce the theoretical formula of the depth hr of the large-diameter rock-socketed pile embedded in the bedrock. It is verified through both experiments and numerical analysis.
8
Content available Doświadczalne określanie nośności belek stalowo-betonowych zespolonych za pomocą łączników niespawanych
Nawrot J.
Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo
|
2014
|
Z. 20 (170)
175--181
PL
W artykule omówiono doświadczalne określanie nośności granicznej zespolonych belek stalowo-betonowych dla dwóch wybranych sposobów zespolenia (za pomocą łączników niespawanych). Zaprezentowano postacie zniszczenia dla obu rozważanych przypadków oraz omówiono czynniki wpływające na nośność belek.
EN
The article discusses experimental determination of the bearing capacity of steel-concrete composite beams for the two fixation methods (with non-welded shear connectors). Failure models are presented for both the considered cases and the factors affecting the strength of beams are discussed.
9
Content available Wpływ sposobu zagęszczania gleby na przebieg krzywych doświadczalnych oraz wyznaczaną wartość jej naprężenia granicznego
Wojciech J., Śnieg M.
Inżynieria Rolnicza
|
2012
|
R. 16, nr 2, t. 2
327-336
PL
W artykule przedstawiono cztery sposoby zagęszczania modelowych próbek glebowych, podczas wyznaczania naprężenia granicznego gleby. Wyróżniono powszechny "stary" oraz zmodyfikowany "nowy" sposób pomiaru, a także uwzględniono występowanie możliwej i ograniczonej bocznej rozszerzalności. Badania przeprowadzono na glinie średniej, poddanej zagęszczaniu w metalowych cylindrach na maszynie wytrzymałościowej Instron 5582. Wyniki doświadczenia przedstawiono na wykresach krzywych odkształcenia gleby w funkcji nacisku wykazując, że w zmodyfikowanym sposobie nie występuje etap "dopasowania się" stempla do powierzchni próbki, przy przejściu z formowania pierwotnego w zagęszczenie wtórne. Miało to swoje odzwierciedlenie w wyznaczonych wartościach naprężenia granicznego gleby.
EN
Four methods of concentration of model soil samples during determination of ultimate bearing capacity of soil were presented. A popular "old" and a modified "new "method" of measuring was singled out and occurrence of a possible and a limited side expandability was included. The research was carried out at medium loam, subjected to compaction in metal cylinders in Instron 5582 testing machine. Results of the experiment were presented on diagrams of soil deformation curves as the function of pressure, proving that in the modified method there is no stage of "adjustment" of a punch to the surface of a sample at the transfer from original forming into secondary compaction. It was reflected in the determined values of ultimate bearing capacity of soil.
10
Strength of weak floor strata beneath rock pillars
Pytel W., Pałac-Walko B.
Cuprum : czasopismo naukowo-techniczne górnictwa rud
|
2011
|
nr 3
5-14
EN
A simplified method for stratified floor strata ultimate bearing capacity (UBC) assessing, in room-and-pillar mining conditions, is presented. The physical problem consists of the following two different cases of rectangular rigid pillar of size BxL resting on a two-layer floor system: (a) with the upper weaker layer of thickness H overlying a stronger, infinite rock deposit. It has been assumed that bearing capacity of floor strata may be analyzed as a shallow foundation problem, using the general bearing capacity equation given by Brinch Hansen with appropriate shape, inclination, and surcharge depth factors, or may be treated as a punching failure problem, particularly in a case of relatively strong upper stratum presence. A broad review of available analytical techniques did show that a finite thickness of the upper weaker layer causes a significant increment/decrement in its ultimate bearing capacity in comparison with homogeneous conditions. The proposed approach has been also validated by numerical modeling utilizing FLAC3D the finite difference computer code.
PL
W artykule przedstawiono uproszczoną metodę szacowania nośności uwarstwionego spągu, dla warunków eksploatacji metodą filarowo-komorową. Model fizyczny zagadnienia opisuje przypadek prostokątnego, sztywnego filara o wymiarach BxL spoczywającego na dwuwarstwowym układzie spągu bezpośredniego, ze słabszą warstwą położoną wyżej o grubości H, zalegającą nad mocniejszą warstwą skalną o nieskończonej miąższości. Przyjęto, że nośność podłoża może być analizowana jako przypadek fundamentu bezpośredniego poprzez ogólne równanie nośności zaproponowane przez Brincha Hansena, z zachowaniem odpowiedniego kształtu, nachylenia oraz współczynnika zagłębienia. Przegląd dostępnych matematycznych analiz stosowanych dla opisanego problemu wskazuje, że skończona miąższość słabszej warstwy powoduje wzrost/spadek wartości nośności, w porównaniu z warunkami panującymi w górotworze jednorodnym. Proponowane podejście rozwiązania problemu zostało zweryfikowane przy zastosowaniu metod numerycznych wykorzystujących metodę różnic skończonych (FLAC3D).
11
Content available remote Nośność graniczna podłoża gruntowego według PN-81/B-03020 i Eurokodu 7
Pieczyrak J.
Zeszyty Naukowe Politechniki Białostockiej. Budownictwo
|
2006
|
Z. 28, t. 2
197-211
PL
Niebawem wejdzie w życie norma europejska Eurokod 7. W zakresie nośności podłoża gruntowego, zmianie ulegną współczynniki nośności i kształtu oraz sposób ujmowania zapasu bezpieczeństwa. W efekcie zmianie ulegną obliczeniowo ustalane oceny nośności podłoża gruntowego. W referacie pokazano różnicę pomiędzy ocenami wykonanymi według zasad PN-81/B-03020 i Eurokod 7. Analizie poddano grunty spoiste i niespoiste, dla których parametry geotechniczne ustalono metodą B. Okazuje się, że w przypadku przyjęcia fD = 1, różnice te są niewielkie, aczkolwiek ocena według Eurokodu 7 na ogół jest ostrożniejsza.
EN
A new document - Eurocode 7 will come into effect very soon. In the field of bearing capacity of subsoil the factors of bearing capacity, factors of shape and the way of expressing safety margin will be changed. In effect, the evaluation of bearing capacity of subsoil estimated in computational way will be changed. In the paper the differences between the evaluation of bearing capacity estimated according to the rule in Polish Standard PN-81/B-03020 and Eurocode 7 are presented. Cohesive and noncohesive soils with the parameters estimated with method B were analyzed in this paper. It is shown that for fD=1, the differences between the evaluation of bearing capacity are insignificant, although in general the evaluation according to Eurocode 7 is more careful.
12
Content available remote Assessment of ultimate bearing capacity of RG section affected by mineral oil
Błaszczyński T., Ścigałło J.
Archives of Civil and Mechanical Engineering
|
2006
|
Vol. 6, no 2
41-56
EN
Bering capacity of RC sections subjected to bending and accentric compression and being under the influence of oil evaluated. Two stages of oiling up are considered: non-oiling up state and oiling up state after 12 months of subjecting the RC section to oil influence. Ultimate bearing capacity of reinforced sections influenced by minertal oils is evaluated numerically based on the diagrams of the limit state interactiuon. The analysis is carried out for rectangular section with tension and compression reinforcemenr. In the case oiling up state, the bearing capacity of a section decreases compared with that being in nonoiling state.
PL
Przedstawiono ocenę granicznej nośności zaolejonego przekroju żelbetowego poddanego zginaniu i mimośrodowemu ściskaniu8. Rozważono dwa stany: niezaolejony i zaolejony (po 12 miesiącach oddziaływania oleju mineralnego). Graniczna nośność przekroju zbrojonego zaolejanego olejami mineralnymi oceniono numerycznie, wykorzystując krzywe graniczne. Analizy przeprowadzono dla przekroju prostokątnego podwójnie zbrojonego. Wykazano, że w stanie zaolejonym nośność graniczna przekroju żelbetowego jest mniejsza niż w stanie niezaolejonym.
13
Content available remote Nośność graniczna na zginanie belek zbrojonych kompozytami
Plewako Z.
Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska
|
2000
|
z. 32[180], cz.1
403-409
EN
Determining of ultimate bearing capacity for bending concrete cross-sections and beams with non-metallic, composite, fully elastic reinforcement (FRP), leads to more time-consuming calculations then for steel reinforcement, but universal applying of personal computers allows to overcoming these difficulties. It is important to determine strain in reinforcement arising due to pretensioning, time effects and load actions on element, because its influence on bearing capacity is significant. Main problem for discuss is assuming design strength of FRP materials and corresponding ultimate strains.
14
Content available remote Nośność graniczna smukłych elementów żelbetowych ze zbrojeniem sztywnym mimośrodowo ściskanych
Małek E.
Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo
|
2000
|
Z. 8 (152)
11-19
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