Experimental and numerical studies of T-shaped footings

Nihat Kaya (Author), Murat Ornek (Author)

Abstract

In addition to vertical axial loads, the footings of structures are often subjected to eccentric loads caused by the forces of earth pressures, earthquakes, water, wind, etc. Due to eccentric loading, the two edges settle by different amounts, causing the footing to tilt and then the pressure below the footing does not remain uniform. The T-shape is proposed as a footing shape for improving the bearing capacity of shallow footings against the action of eccentric loads. The vertical insertion of the rigid T-shaped footing, into the bearing soil, provides considerable resistance, against both of sliding and overturning, enough to regain the reduction in bearing capacity and increase in settlement. In this study, a series of experimental and numerical results from the ultimate loads and settlement of T-shaped footings are reported. A total of 48 model tests were conducted for investigating the effects of different parameters, such as the problem geometry and soil density. The problem geometry was represented by two parameters, the load eccentricity (e) and the insertion depth (H) of the T-shape into the loose and dense sand soil. After the experimental stage, the numerical analyses were carried out using a plane strain, two-dimensional, finite-element-based computer program. The behaviour of the T-shape footing on sand beds is represented by the hardening soil model. The results of the experimental and numerical studies proved that the ultimate bearing capacity of a footing under eccentric loads could be improved by inserting a vertical central cut-off rigidly connected to the footing bottom. The load settlement curves indicate that the higher load eccentricity results in a decrease in the bearing capacity of the strip footing. It was also proved that the ultimate bearing capacity values can, depending on the soil density, be improved by up to four times that of the loose sand case. This investigation is considered to have provided a useful basis for further research, leading to an increased understanding of the T-shaped footing design.

Keywords

model test;finite-element method;T-shaped footing;eccentric loading;sand;

Data

Language:	English
Year of publishing:	2013
Typology:	1.01 - Original Scientific Article
Organization:	UM FGPA - Faculty of Civil Engineering, Transportation Engineering and Architecture
UDC:	624.131.522
COBISS:	277747968
ISSN:	1854-0171
Parent publication:	Acta geotechnica Slovenica
Views:	643
Downloads:	43
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Other data

Secondary language:	Slovenian
Secondary title:	Eksperimentalne in numerične študije T-oblikovanih temeljev
Secondary abstract:	Temelji konstrukcij so podvrženi vertikalnim osnim obremenitvam, pogosto pa tudi ekscentričnim obremenitvam, ki jih povzročajo sile zemeljskega pritiska, potresov, vode, vetra itd. Zaradi ekscentričnih obremenitev se robova temelja posedata različno, kar povzroči nagibanje temelja in spremembo pritiska pod temeljem. Predlagana T-oblika temelja naj bi izboljšala nosilnost plitkih temeljev pri ekscentričnih obremenitvah. Pri vertikalni vstavitvi togih T-temeljev v nosilno zemljino pride do precejšnjega upora proti drsenju in prevrnjenju, ki je tako velik, da se nosilnost še zmanjša in posedanje poveča. V članku so predstavljeni številni eksperimentalni in numerični rezultati posedanja temeljev zaradi skrajnih obremenitev. Za preučevanje vplivov različnih parametrov, kot npr. problema geometrije in gostote zemljine, smo pripravili 48 modelnih preizkusov. Problem geometrije smo predstavili z dvema parametroma, ekscentričnostjo obremenitve (e) in globino vstavljanja (H) T-temelja v rahlo in gosto peščeno zemljino. Eksperimentalnemu delu so sledile še numerične analize, za katere smo uporabili računalniški program za ravninske deformacije z dvodimenzionalnimi končnimi elementi. Obnašanje T-temelja na peščenih posteljicah smo predstavili z modelom uterjevanja zemljine. Rezultati eksperimentalnih in numeričnih študij dokazujejo, da se lahko nosilnost temelja pri skrajnih ekscentričnih obremenitvah izboljša z vstavljanjem vertikalnega centralnega dela, ki se togo pritrdi na dno temelja. Krivulje posedanja zaradi obremenitve kažejo, da višja obremenitev privede do zmanjšanja nosilnosti pasovnega temelja. Dokazali so tudi, da se lahko glede na gostoto zemljine, v primerjavi z rahlim peskom, nosilnost temelja izboljša do štirikrat. Menimo, da je dala raziskava koristno osnovo za nadaljnje raziskovanje in omogočila boljše razumevanje T-temeljev.
Secondary keywords:	geomehanika;temelji konstrukcij;obremenitve;modeli;metoda končnih elementov;
URN:	URN:SI:UM:
Type (COBISS):	Scientific work
Pages:	str. 42-59
Volume:	ǂVol. ǂ10
Issue:	ǂ[no.] ǂ1
Chronology:	2013
ID:	10941236