natgillin/translations-raw huggingface dataset:
Beyond 15 % of LECA content, the compressive strength reduces, which is probable due to either weaker nature or very prounced water absorption characteristics of the LECA aggregate.
Iznad 15 % količine LECA agregata dolazi do smanjenja tlačne čvrstoće betona, što je vjerojatno posljedica ili slabije strukture ili vrlo izraženog svojstva vodoupojnosti LECA agregata.
For SCSCC with 15 % of LECA, the compressive strength under self curing is by 1.84 % higher compared to that of the control concrete.
Kod SCSCC betona s 15 % LECA agregata, tlačna čvrstoća uslijed procesa unutarnje njege je za 1,84% veća od odgovarajuće vrijednosti tlačne čvrstoće
The results obtained are in conformity with the results published by Maghsoudi et.al and Magda et.al [13, 14].
Dobiveni rezultati u skladu su s rezultatima koje su objavili Maghsoudi i dr. te Magda i dr. [13, 14].
The compressive strength will not be affected by self curing when the required amount of prewetted lightweight aggregate is used in the concrete [18, 19].
Unutarnja njega neće utjecati na tlačnu čvrstoću ako se betonu doda potrebna količina prethodno navlaženog laganog agregata [18, 19].
However, weaker LWA as self curing agent in concrete might reduce the strength [20].
Međutim, kada se za unutarnju njegu upotrijebiti slabiji lagani agregat, tada može doći do smanjenja čvrstoće betona [20].
b shows that the trend in compressive strength for the SCSCC with FAA as self curing agent at 7 & 28 days is similar to that of the SCSCC with LECA.
b. pokazuje da je trend tlačne čvrstoće SCSCC betona s dodatkom FAA agregata, kao sredstva za unutarnju njegu, pri starosti 7 i 28 dana sličan trendu tlačne čvrstoće SCSCC betona s dodatkom LECA agregata.
However, the compressive strength of the FAA incorporated SCSCC is significantly higher at 7 and 28 days compared to the SCSCC with LECA as self curing agent.
Međutim, tlačna čvrstoća SCSCC betona s dodatkom FAA agregata pri starosti 7 i 28 dana je znatno veća od odgovarajuće vrijednosti tlačne čvrstoće SCSCC betona s dodatkom LECA agregata kao sredstva za unutarnju njegu.
Also, the compressive strength of SCSCC improves under self curing with an increase in the FAA content of up to 15 %.
Osim toga, tlačna čvrstoća SCSCC betona poboljšava se uslijed procesa unutarnje njege s povećanjem količine FAA agregata od najviše 15 %.
Nevertheless, the compressive strength reduces beyond 15 %.
No ako se dodaje veća količina FAA agregata, tada dolazi do smanjenja tlačne čvrstoće .
Unlike the LECA incorporated SCSCC, the compressive strength of SCSCC with 20 % and 25 % of FAA is higher than that of the control concrete.
Za razliku od SCSCC betona s dodatkom LECA agregata, tlačna čvrstoća SCSCC betona s dodatkom 20 % i 25 % FAA agregata veća je od odgovarajuće vrijednosti tlačne čvrstoće kontrolnog betona.
It is due to the fact that the water absorption of FAA is significantly lower than that of the LECA aggregate, and to the pozzolanic reaction between the cement and fly ash.
Razlog tomu je činjenica da je vodoupojnost FAA agregata bitno manja od vodoupojnosti LECA agregata te postojanje pucolanske reakcije do koje dolazi između cementa i letećeg pepela.
b), flexural strength (Figures 5.
a I 4.
a and 5.
b), čvrstoće savijanjem (slike 5.
b), and the modulus of elasticity (Figures 6.
a i 5b) te modula elastičnosti (slike 6.
It can be observed that the trends in the split tensile strength, flexural strength, and modulus of elasticity of the LECA SCSCC and FAA SCSCC are similar to those of the compressive strength.
Može se uočiti da su trendovi vlačne čvrstoće cijepanjem, čvrstoće savijanjem i modula elastičnosti mješavina LECA SCSCC betona i FAA SCSCC betona slični trendovima dobivenim za tlačnu čvrstoću.
Slump flow
Konzistencija rasprostiranjem
V-funnel
V-lijevak
J-ring
J-prsten
U-box
U-kutija
L-box
L-kutija
Properties of hardened self compacting self curing concrete
Svojstva samozbijajućeg betona s unutarnjom njegom u očvrslom stanju
Flexural strength
Čvrstoća savijanjem
CMwc - Control Mix with water curing; CMrt - Control Mix kept at room temperature; SD = Standard Deviation; COV = Coefficient of Variance [%]
CMwc - kontrolna mješavina betona njegovanog vodom; CMrt - kontrolna mješavina betona njegovanog pri sobnoj temperaturi; SD - standardna devijacija; COV - koeficijent varijancije [%]
Compressive strength of SCSCC: a) with LECA; b) with FAA
Tlačna čvrstoća SCSCC betona: a) s dodatkom LECA agregata; b) s dodatkom FAA agregata
The filling ability, passing ability, and segregation resistance of all SCSCC mixes with LECA and FAA are in conformity with EFNARC standards.
Sposobnost popunjavanja, sposobnost zaobilaženja prepreka i otpornost segregaciji svih mješavina SCSCC betona s dodatkom LECA i FAA agregata u skladu su sa zahtjevima normi EFNARC.
The early compressive strength of the LECA and FAA incorporated SCSCC concrete is significantly lower than that of the control concrete.
Rana tlačna čvrstoća SCSCC betona s dodatkom LECA i FAA agregata bitno je niža od odgovarajuće tlačne čvrstoće kontrolnog betona.
However, a significant improvement in compressive strength has been noted at 28 days.
Međutim, zabilježen je značajan porast tlačne čvrstoće pri starosti 28 dana.
For the SCSCC with 15 % of LECA, the compressive strength under self curing is by 1.84 % higher compared to that of the
Kod SCSCC betona s 15 % LECA agregata, tlačna čvrstoća uslijed procesa unutarnje njege
Flexural strength of SCSCC: a) with LECA; b) with FAA
Čvrstoća savijanjem SCSCC betona: a) s dodatkom LECA agregata; b) s dodatkom FAA agregata
Modulus of elasticity of SCSCC: a) with LECA; b) with FAA
Modul elastičnosti SCSCC betona: a) s dodatkom LECA agregata; b) s dodatkom FAA agregata
Split tensile strength of SCSCC: a) with LECA; b) with FAA
Vlačna čvrstoća cijepanjem SCSCC betona: a) s dodatkom LECA agregata; b) s dodatkom FAA agregata
Also, the compressive strength of SCSCC with 20 % and 25 % of FAA is higher than that of the control concrete, unlike the LECA incorporated SCSCC.
Osim toga, tlačna čvrstoća SCSCC betona s dodanih 20 % i 25 % FAA agregata veća je od odgovarajuće tlačne čvrstoće kontrolnog betona, što nije slučaj kod SCSCC betona s dodatkom LECA agregata.
The SCSCC with 15 % of LWA exhibits the maximum tensile strength, flexural strength and modulus of elasticity values.
SCSCC beton s 15 % laganog agregata postiže najveće vrijednosti vlačne čvrstoće, čvrstoće savijanjem i modula elastičnosti.
Prof. Radomir Folić, PhD. CE
Radomir Folić, dipl.ing.građ.
University of Novi Sad
Sveučilište u Novom Sadu
Faculty of Technical Sciences
Fakultet tehničkih nauka
Department of Civil Engineering folic@uns.ac.rs
Odjel za građevinarstvo folic@uns.ac.rs
Punching of column footings - comparison of experimental and calculation results
Proboj temelja samaca - usporedba proračuna i eksperimenta
Key words: punching, shear stresses, foundations, codes, experiments, comparative analysis
Ključne riječi: proboj, posmična naprezanja, temelji, propisi, eksperimenti, usporedna analiza
Proboj temelja samaca - usporedba proračuna i eksperimenta
Punching of column footings - comparison of experimental and calculation results
Proboj stupa kroz ploču najčešće se vezuje za međukatne konstrukcije, rjeđe i za ploče temelja samaca ispod stupova.
The column punching through the slab is most often related to floor structures, and less often to foundation slabs under columns.
Proračunski modeli za ova dva problema često nisu razdvojeni.
Calculation models for these two problems are often not separated.
Zbog nedostatka eksperimentalnih rezultata na temeljima, primjenjuju se modeli za međukatne ploče.
The deficit of experimental results for column footings results in the use of floor slab models.
U radu je prikazan pregled literature o teorijskim i eksperimentalnim istraživanjima i propisi za proračun proboja stupa kroz ploču.
A review of the theoretical and experimental research references, including Codes/Regulations for punching calculation of column footings, is presented in the paper.
Opisan je program eksperimentalnih istraživanja i njegova realizacija.
The experimental research program and its implementation is described.
Dobiveni rezultati uspoređeni su s rezultatima proračuna prema različitim propisima.
The results obtained are compared with calculation results based on various regulations.
Dane su preporuke i naznačene smjernice budućih istraživanja.
Recommendations and directions for future research are outlined.
Ključne riječi: proboj, posmična naprezanja, temelji, propisi, eksperimenti, usporedna analiza
Key words: punching, shear stresses, foundations, codes, experiments, comparative analysis
Foundations connect and coordinate the work of the structure with the subgrade, whose characteristics in relation to the structure are very different, particularly in terms of deformability.
Temelji povezuju i usklađuju ponašanje konstrukcije građevine s podlogom, čije su karakteristike u odnosu na konstrukciju vrlo različite, naročito s aspekta deformabilnosti.
Although foundations have a significant impact on the behaviour of the structure and the surrounding soil, their calculation has not been sufficiently considered, neither in literature nor in technical regulations (standards, norms, requirements).
Iako temelji bitno utječu na ponašanje konstrukcije i okolnog tla, njihovom se proračunu ne posvećuje dovoljna pažnja niti u stručnoj literaturi niti u tehničkim propisima (standardi, norme, zahtjevi).
Approximate calculations are most often used in the design of shallow foundations, particularly column footings, which are considered as rigid foundations, and a linear distribution of contact pressures is adopted.
Pri projektiranju plitkih temelja, naročito temelja samaca, najčešće se primjenjuju približni proračuni gdje se temelji smatraju krutim i usvaja linearna raspodjela kontaktnih pritisaka.
In this calculation, a considerable significance is given to the punching shear control, i.e. to the control of column punching through the floor slab with or without shear reinforcement for the assumption of shear in the column area.
U takvom proračunu važan dio predstavlja kontrola temelja na proboj (engl. punching) uslijed posmika, tj. provjera proboja stupa kroz ploču s armaturom ili bez armature za prihvat posmika u području stupa.
This control, as well as the punching control of floor slabs, are usually based on experimental research.
Ona se, kao i kontrola proboja međukatnih ploča, najčešće zasniva na eksperimentalnim istraživanjima.
Due to a small number of experiments aimed at studying the puncture strength of foundation slabs, their analysis is often based on theoretical and/or empirical equations such as those applied to the problem of column punching through floor slabs, which is based on experimental research [1-6].
Zbog malog broja eksperimenata usmjerenih na istraživanje ponašanja temeljne ploče na proboj, često se za njihovu analizu koriste teorijske i/ ili empirijske odredbe kao kod problema proboja stupa kroz međukatnu ploču zasnovanog na eksperimentalnim radovima [1-6].
A broader historical review of solutions to column punching through the slabs without shear reinforcement is given in [7], but here the focus is mostly on punching through floor slabs.
Širi povijesni pregled rješenja problema proboja ploča bez armature za prihvat posmika dan je u radu [7], ali je uglavnom opisan i objašnjen proboj stropova.
At that, it is noted that first recommendations of the American Concrete Institute (ACI) on flat plates, given in 1925, were based on experimental results presented byTablot [8], who investigated column footings, as cited in [7].
Pri tome je naglašeno da su prve preporuke Američkog instituta za beton (ACI) iz 1925. g. za ravne ploče, bile zasnovane na eksperimentalnim rezultatima Tablota [8], koji je istraživao temeljne ploče citirano prema [7].
However, the difference between the punching mechanism of foundation plates and floor slabs, which is due to their considerable difference in height ("slenderness"), has generally been neglected in technical regulations (hereinafter referred to as "regulations") [9].
Ipak, u tehničkim propisima (u daljnjem tekstu propisi) uglavnom je zanemarivana razlika mehanizma proboja ploča temelja i međukatnih ploča koja nastaje uslijed njihove znatne razlike u visinama ("vitkosti") [9].
This is due to the fact that experimental research relating to foundations has so far been quite scarce, primarily because of the complicated organization of such experiments, higher material costs, and a number of significant parameters that need to be taken into account.
Razlog je tomu što su eksperimentalna istraživanja na temeljima do sada bila znatno rjeđa, prije svega zbog složene organizacije eksperimenta, većih materijalnih izdataka i brojnih utjecajnih parametara koje treba razmatrati.
Here, It should also be noted that investigations in real soil are rare and expensive, and so in many experiments real conditions are simulated by steel springs or BY a set of small hydraulic jacks connected in parallel [3].
Pri tome treba uzeti u obzir da su istraživanja na realnom tlu rijetka i skupa, pa je u više eksperimenata podloga simulirana čeličnim oprugama ili skupom malih hidrauličnih preša paralelno povezanih [3].
With regard to the punching control of foundations plates, technical regulations allow subtracting the load from the superstructure for a part of soil reaction, but differences between some regulations/standards are quite noticeable [9].
Tehnički propisi dopuštaju da se pri provjeri temeljnih ploča na proboj dio vrijednosti reakcije tla oduzme od opterećenja gornje konstrukcije, ali su primjetne razlike u pojedinim normama/propisima [9].
This is the why 17 column footings are studied in [9] (five actually resting on sand to enable analysis of the soil-structure interaction).
To je razlog da je u [9] prikazano 17 ispitivanih temelja (pet realno oslonjenih na pijesak radi proučavanja interakcije konstrukcija-tlo).
The varied parameter was the shear span (b) (leg b marked in Figure 4) to effective depth (d) ratio, with values between 1.25 and 2.0, while the concrete strength was between 20 and 40 MPa.
Varirani parametar je bio odnos raspona (kraka) posmika (b) (krak b obilježen na slici 4. i efektivne visine (d) s vrijednostima između 1.25 i 2.0, a čvrstoća betona je bila između 20 i 40 MPa.
According to [11], the most important parameters that should be included in the finite element method (FEM) are: geometry, material properties, and flexural reinforcement.
Najvažniji su parametri koje treba obuhvatiti pri analizi metodom konačnih elemenata (MKE), prema [11], geometrija te karakteristike materijala i armature za prihvat savijanja.
The specificity of column footings is that they have a small b/d ratio.
Prikazano je obuhvaćanje najvažnijih parametara mehanike loma za opis duktilnosti ili krtosti (engl. brittleness).
The punching test for two circular columns passing through the footing has been simulated numerically by means of the FEM [10].
Test proboja dvaju kružnih stupova kroz temelj simuliran je numerički MKE u [10].
It was established that failure mechanisms of slender slabs are significantly different from the mechanism related to footings.
Pokazano je da se mehanizmi loma vitkih ploča bitno razlikuju od onoga kod temelja.
It is stated that the angle of shear cracks at foundation plates is between 50 - 60 0, which is significantly higher than the angle for slender slabs (30 - 40 0).
Navodi se da je kut nagiba posmičnih pukotina temelja između 50 0 i 60 0 znatno veći nego kod vitkih ploča (30-40 0).
The b/d ratio for foundation plates is much smaller compared to the ratio applied for floor slabs (most regulations are based on them).
Odnos b/d temelja je znatno manji nego kod međukatnih ploča (većina propisa se zasniva na njima).
It has been established by parametric analyses that the compressive strength of concrete has a greater impact on the punching bearing capacity of column footings, compared to "slender" plates that are typical to floor slabs.
Parametarskim analizama je ustanovljeno da tlačna čvrstoća betona ima veći utjecaj na nosivost ploče temelja stupa na proboj nego što je to kod "vitkih" ploča karakterističnih za stropove.
It should be noted that the punching failure through a footing is brittle, and so the failure of one column/support can lead to the progressive and unexpected failure of neighbouring supports, as cracks and deformations remain small until just prior to the actual failure.
Treba imati na umu da je lom probojem stupa kroz ploču krt i da lom jednog stupa/oslonca može dovesti do progresivnog i nenagoviještenog loma i na susjednim osloncima, jer pukotine i deformacije ostaju male sve do trenutka neposredno prije loma.
The use of shear reinforcement increases the punching capacity significantly, while also contributing to the increase in ductility and the possibility of redistribution of forces [12].
Korištenje armature za prihvat posmika značajno povećava nosivost na proboj uz povećanje duktilnosti i mogućnost redistribucije sila [12].
It is emphasized in the same paper that most models described in regulations and literature are related to empirical connections, and that they do not contribute to the understanding of phenomena, which is why their introduction into the analysis is more difficult.
U istom radu je naglašeno da se većina modela u propisima i literaturi odnosi na empirijske veze i da ne pridonose razumijevanju fenomena pa je njihovo uvođenje u analizu otežano.
The theory of plasticity, fracture mechanics, and nonlinear finite element method, are increasingly used in theoretical analyses.
U teorijskim analizama sve više se primjenjuje teorija plastičnosti, mehanika loma i nelinearna metoda konačnih elemenata (MKE).
The absence of properly developed theories that would explain behaviour of reinforced concrete slabs has lead to practical use of models contained in various technical regulations.
Zbog nedostatka razvijene teorije kojom bi se objasnilo ponašanje armiranih ploča, u praksi se primjenjuju modeli iz različitih tehničkih propisa.
In Switzerland, the shear reinforcement is calculated on the basis of the theory of plasticity, according to SIA 262.
U Švicarskoj se posmična armatura proračunava na bazi teorije plastičnosti prema normi SIA 262.
At that, rough approximations are made, and the contribution of concrete to punching capacity is neglected, which leads to conservative calculation results for shear reinforcement.
Pri tome se čine gruba pojednostavljenja, zanemarujući doprinos betona nosivosti na posmik, što vodi konzervativnim rezultatima proračuna posmične armature.
Generally, technical regulations do not distinguish between punching through floor slabs and punching through foundation slabs.
U tehničkim propisima se uglavnom ne pravi razlika između proboja stupa kroz strop i kroz ploču temelja.
The comprehensive monograph fib 12 [13] also places a high emphasis on the problem of column
I u opsežnoj monografiji fib 12 [13] pretežno je razmatran problem proboja stupa kroz ploču kod stropova.
Punching of column footings - comparison of experimental and calculation results
Banka podataka sadrži pokuse za ploče s armaturom i bez armature za posmik.
The application of this theory to the punching of slabs with transverse reinforcement is presented in [16].
Primjena ove teorije na proboj ploče s poprečnom armaturom prikazana je u radu [16].
In the draft of the new fib Model Code 2010 [17], provisions for the punching-related slab design point to the above-mentioned CSCT formulated by A. Muttoni, and also to papers [14] and [16].
U fib draft novog modela Code fib 2010 [17] odredbe za projektiranje ploča na proboj upućuju na prije spomenutu TKSP, na engleskom (CSCT), koju je formulirao A. Muttoni, i na radove [14 i 16].
This is regulated in the draft [17] by provisions contained in section 7.3.5.
To je u draftu [17] navedeno u poglavlju
In order to test some regulations and their applicability to the punching resistance calculation of column footings, an experimental program was conducted in the scope of paper [18].
Da bi se ispitali pojedini propisi i njihova primjenljivost na proračun posmične otpornosti ploče temelja samca, u okviru rada [18] realiziran je eksperimentalni program.
The program of experimental investigations was made with goals that have also been set by some other researchers [3].
Program eksperimentalnih istraživanja sastavljen je s ciljem koji su postavili i neki drugi istraživači [3].
The column footing punching behaviour was studied so as to obtain answers to the following questions: how does the soil pressure distribution at the base of the footing affect the punching bearing capacity, and what is the difference in behaviour between floor slabs and foundation slabs in terms of column punching through the slab?
Proučavano je ponašanje temelja na proboj radi dobivanja odgovora o tome kako utječe raspodjela pritisaka tla u dnu temelja na kapacitet nosivosti na proboj i kakva je razlika ponašanja međukatnih i temeljnih ploča iz aspekta proboja stupa kroz ploču.
During the tests, punching mechanisms have also been registered, especially the angles at which shear cracks are formed.
Tijekom ispitivanja registrirani su i mehanizmi loma, naročito kutovi pod kojima se formiraju posmične pukotine.
The above overview points to the need for comparative analysis of experimental results and provisions contained in appropriate regulations.
Prethodno prikazani pregled upućuje na potrebu uspoređivanja odredbi pojedinih propisa međusobno i s eksperimentalnim rezultatima.
The comparative analysis comprises the following documents: Byelaw BAB 87 (Byelaw on technical standards for concrete and reinforced concrete ) which was until recently used in a number of countries of our region, and which was implemented on a large number of projects; American ACI 318-02 [22]; British BS 110-1-1997 [20]; German DIN 1045-1 [21]; European EN 1992 EC-2 [22], and Russian regulations SNiP-84 [23].
Usporednom analizom obuhvaćeni su: Pravilnik BAB 87, koji je donedavno primjenjivan u zemljama regije i prema njemu je realiziran velik broj građevina; američki ACI 318-02 [22]; britanski BS 110-1-1997 [20]; njemački DIN 1045-1 [21]; europske EN 1992EC 2 [22] i ruski propisi SNiP-84 [23].
A modified model based on the Model Code (fib) [24] and EN 1992-1: 2004, and also on the European Concrete Platform from 2010 [25], is proposed in this paper.
U ovom radu predložen je modificirani model zasnovan na Model Code (fib) [24] i EN 1992-1: 2004 te na Platformi iz 2010. godine [25].
The above regulations were compared based on the results obtained by experimental testing of the column footings punching on a gravel bedding.
Međusobna usporedba navedenih propisa provedena je na osnovi rezultata eksperimentalnih ispitivanja pri probijanju temelja samaca na podlozi od šljunka.
The punching failure of the column footing supported by gravel was recorded by varying the slab height: 10; 12.5; 15.0; 17.5; 20.0 and 25.0 cm.
Lom posmikom temeljne ploče oslonjene na šljunak registriran je uz variranje visine ploče od 10;12.5; 15.0; 17.5; 20.0 i 25.0 cm.
2. Comparative review of some experiments
2. Pregled provedenih eksperimenata
According to published data, a relatively small number of punching tests for column footings resting on a real bedding has been realized since the start of the twentieth century [18].
Prema objavljenim podacima od početka dvadesetog stoljeća do danas realiziran je relativno mali broj ispitivanja proboja na temeljima koji su bili oslonjeni na realnu podlogu [18].
The tests carried out by Dieterle and Rostasy, Kordina and Nölting, and Dieterle and Steinle, cited in [3], are also quite significant.
Ispitivanje proboja temelja na realnom tlu praktično su proveli jedino Hegger i ostali [3-4] - u sanduku pijeska i Rivkin [27] - na glini in situ.
The data about geometric characteristics, the number of tested footings, and supports used, are clearly arranged and presented in Table 1.
Obuhvaćeni su propisi ACI (1983), BS (1985), CEB-FIP (1990), prEN (1991) i dva japanska propisa: prvi je Architectural Institute of Japan (AIJ), a drugi Japan Society of CE (JSCE).
Type of support
Način oslanjanja
Number of tested footings
Broj ispitanih temelja
Geometry of footing
Geometrija temelja
Shape
oblik
Dimension [mm]
dimenzije [mm]