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1

Bearing capacity and seismic performance of Y-shaped reinforced concrete bridge piers in a freeze-thaw environment

Li Yanfeng, Li Jialong, Guo Tianyu, Zhao Tongfeng, Bao Longsheng, Sun Xinglong

Archives of Civil Engineering

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2023

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Vol. 69, nr 1

367--384

EN

A quantitative study is performed to determine the performance degradation of Y-shaped reinforced concrete bridge piers owing to long-term freeze-thaw damage. The piers are discretized into spatial solid elements using the ANSYS Workbench finite element analysis software, and a spatial model is established. The analysis addresses the mechanical performance of the piers under monotonic loading, and their seismic performance under low-cycle repeated loading. The influence of the number of freeze-thaw cycles, axial compression ratio, and loading direction on the pier bearing capacity index and seismic performance index is investigated. The results show that freeze-thaw damage has an adverse effect on the ultimate bearing capacity and seismic performance of Y-shaped bridge piers in the transverse and longitudinal directions. The pier peak load and displacement ductility coefficient decrease with increasing number of freeze-thaw cycles. The axial compression ratio is an important factor that affects the pier ultimate bearing capacity and seismic performance. Upon increasing the axial compression ratio, the pier peak load increases and the displacement ductility coefficient decreases, the effects of which are more significant in the longitudinal direction.

2

Investigation of Resilience of Eccentrically Braced Frames Equipped with Shape Memory Alloys

Pirmoghan Hamid, Khoshravi Hossein, Sadeghi Abbasali, Pouraminian Majid, Noroozinejad Farsangi Ehsan

Civil and Environmental Engineering Reports

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2022

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Vol. 32, no. 1

176--190

EN

Nowadays, the use of smart materials in structures is a major concern to structural engineers. The act of benefiting from numerous advantages of these materials is the main objective of researches and studies focused on seismic and structural engineering. In the present study, in addition to the development of finite element models of several steel frames using ABAQUS software, the effect of shape memory alloys (SMAs) on superelastic behavior and the various types of eccentric braces will be checked. Moreover, it was observed that the use of SMAs within various types of bracing systems of steel frames leads to a decrease in the reduction factor of the frames. Also, the eccentric bracing in which SMAs are utilized in the middle of bracing led to the highest effect on reduction of lateral drift of the frames and decrease of reduction factor. The obtained results indicated that the application of smart materials led to increasing of strain energy and base shear of the first plastic hinge, which is followed by a decrease in the reduction factor of the frame.

3

Experimental study on seismic performance of double-level yielding buckling-restrained braced concrete frames

Zhang Zhe, Zhang Sheng-Nan, Deng En-Feng, Zhou Tong-Tong, Yi Yu, He Hao, Li Na-Na

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 2

191--206

EN

This paper focused on the seismic performance of buckling-restrained braced concrete frame. Two different systems including the single-level yielding buckling-restrained braced concrete frame (SYBRBCF) and the double-level yielding buckling-restrained braced concrete frame (DYBRBCF) were designed for comparison. Compared with the single-level yielding buckling-restrained braces which are similar to many existing types of buckling-restrained braces, the double-level yielding buckling-restrained braces (DYBRBs) have two different energy absorption mechanisms that are expected to provide energy dissipations under the frequent earthquakes and rare earthquakes. To comparatively investigate the seismic performances of the two systems, cyclic tests were performed on one DYBRBCF specimen and another SYBRBCF specimen. The seismic response including the hysteretic curves, backbone curves, ductility coefficients, equivalent damping ratios, strengths, and stiffness degradations of the two experimental specimens was compared and analyzed. The test results indicate that the properly designed SYBRBCF and DYBRBCF can both exhibit the full hysteretic curves, meet the strong-column–weak-beam design requirement, and achieve the expected seismic performance. However, it was found that the ductility coefficient and energy dissipation capacity of the DYBRBCF were 72.2% and 23.4% higher than those of the SYBRBCF. The present study also provided useful design recommendations, which were beneficial to promote the application of DYBRBs.

4

Wpływ cementacji na zachowanie się gruntów pod fundamentami budynków w trakcie trzęsienia ziemi

Akyol E., Korkmaz T.

Cement Wapno Beton

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2015

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R. 20/82, nr 5

313--321

PL

W ostatnich dziesięcioleciach wzniesiono dużo budynków na gruntach wątpliwej jakości, co było spowodowane szybkim wzrostem urbanizacji. Spowodowało to wzrost zagrożenia w przypadku wystąpienia trzęsienia ziemi na tych terenach, zwłaszcza jeżeli nie zastosowano w trakcie budowy odpowiednich rozwiązań inżynierskich. Stosuje się cementację gruntu w celu poprawy sejsmicznych właściwości fundamentów, a jego efektywność sprawdzono przez pomiar przeważającego okresu drgań gruntu i szybkości fali ścinającej. Średni wynik pomiarów przeważającego okresu i szybkości fali zmienił się odpowiednio z 0,58 s na 0,23 s i z 374 m/s na 449 m/s. Poprawa właściwości gruntu osiągnęła ponad 50%. Ten wynik pokazuje, że cementacja może korzystnie zmienić zachowanie się słabych sejsmicznie fundamentów budynków w przypadku trzęsienia ziemi. Można więc polecać tę metodę do zmniejszenia ryzyka, związanego z aktywnością sejsmiczną, dla istniejących budynków.

EN

In last decades a large number of buildings is being constructed on problematic soils because of rapid urbanization It causes growing earthquake risks in such areas if combined with lack of engineering. Grouting of ground is being employed to improve seismic performance of foundations and its effectiveness has been verified by examination of predominant period of ground vibration and shear wave velocity. The average period and shear wave velocity of ground was changed from 0.58 s to 0.23 s and 374 m/s to 449 m/s, respectively. The improvement of ground properties reached more than 50%. The results show that grouting can improve earthquake performance of seismically weak building foundations. Thus it can be advised to mitigate the seismic risk of existing buildings.

5

Seismicity in Nigeria : the need for earthquake-resistant structures

Shiwua A. J.

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2013

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Z. 19 (169)

171--178

EN

Nigeria has experienced pockets of tremors of magnitudes ranging from 4.3 to 4.5, even though it is not situated where major seismic activities are observed in the world. In 2000 an earthquake with body wave magnitude of 4.4 occurred in Nigeria and was recorded by some agencies like the International Seismological Centre (ISC). Similarly, the vibrations of the September 11, 2009 event with magnitude 4.4 and epicenter at Allada, Benin Republic, almost 130 km west of Lagos, Nigeria, was felt in parts of Ibadan and Ogun State, south-western Nigeria. Most of the previous tremors occurred in south-western Nigeria where a major fault (the Ifewara-Zungeru fault), is believed to exist. It is difficult to overlook the incidence of earth tremors in the country because recurring tremors could be a build-up to a major earthquake. Despite these events, most buildings in Nigeria are designed without incorporating the effect of seismic load. This paper seeks to reiterate why it is imperative to design earthquake-resistant structures in Nigeria bearing in mind the obvious knowledge of Earth’s dynamism and the country’s history of the earthquake activities.

PL

Nigeria doświadczyła wstrząsów o sile od 4,3 do 4,5 mimo tego, że nie jest położona w obszarze, w którym obserwuje się aktywność sejsmiczną. W 2000 roku w Nigerii miało miejsce trzęsienie ziemi o sile 4,4 i zostało zarejestrowane przez niektóre agencje badawcze, np. Międzynarodowe Centrum Sejsmologiczne (ISC). Podobnie wstrząsy z dnia 11 września 2009 roku o sile 4,4 z epicentrum w Allada (Republika Beninu), położonej około 130 km na zachód od Lagos (Nigeria) były odczuwalne w części Ibaan i Ogun (południowo-zachodnia Nigeria). Większość wcześniejszych wstrząsów miała miejsce w południowo-zachodniej Nigerii, gdzie występuje poważny defekt. Trudno przeoczyć występowanie wstrząsów w Nigerii, które mogą być zapowiedzią większego trzęsienia ziemi. Pomimo tego budynki w Nigerii nie są projektowane z uwzględnieniem oddziaływań sejsmicznych. Niniejsza praca ma na celu przypomnienie o konieczności projektowania konstrukcji odpornych na trzęsienia ziemi z uwzględnieniem wiedzy o dynamice ziemi oraz historii trzęsień ziemi.

6

Seismic analyses of HV bushings

Płatek R.

Przegląd Elektrotechniczny

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2009

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R. 85, nr 3

59-62

EN

The mechanical reliability of critical transformer components is one of the main design aspects being addressed during development of HV equipments, and their safe operation must be ensured against all natural hazards including earthquake activities. This article describes a numerical simulations and the experimental validation on the seismic response of a full-scale high-voltage transformer bushing. The tests and analyses were performed for a 230 kV silicone housed Resin Impregnated Paper (RIP) transformer air bushing, according to the 693-2005 standard defined by IEEE.

PL

Mechaniczna niezawodność krytycznych komponentów transformatora jest jednym z głównych aspektów projektowania podczas rozwoju produktów wysokiego napięcia. Bezpieczne działanie tych produktów powinno być utrzymane niezależnie od naturalnych zagrożeń takich jak trzęsienie ziemi. W artykule opisane jest numeryczne podejście do analiz sejsmicznych przepustów transformatora wysokiego napięcia. Dodatkowo na podstawie testów przeprowadzonych w laboratorium przeprowadzono weryfikacje opisanych analiz numerycznych. Analizy jak i testy zostały przeprowadzone dla przepustu transformatora 230 kV żywicznie impregnowanego papieru (ang. Resin Impregnated Paper – RIP) w osłonie silikonowej na podstawie standardu IEEE 693-2005.

7

Odporność ceglanych budynków mieszkalnych na drgania parasejsmiczne

Marcinkowski J.

Wiadomości Projektanta Budownictwa

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2007

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nr 5

22--25

EN

Only some of damages which appear in masonry building are actually evoked by parsejsmic vibrations. Most of them are caused just by technical wear or other factors like foundation settlement e.g. Only vibrations of comparatively high intensity can evoke damages of masonry buildings. The paper deals with a harmfulness evaluation of vibrations evoked during driving of steel pales in the Zielona Góra center and transmitted on neighbouring masonry buildings. The harmfulness was estimated on the basis of measurements done by specialistic apparatus. The evaluation of harmfulness was performed on the basis of Polish Code PN 85/8-02170 by means of nomograms SWD. Also harmfulness of these vibrations on people present in theses buildings was evaluated as well. It was done on the basis of Polish Code PN 88/B-02171.