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1

Earthquake protection of reinforced concrete structures with infill walls using PUFJ and FRPU systems

Kwiecień Arkadiusz, Akyildiz Ahmet Tugrul

Archives of Civil Engineering

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2023

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Vol. 69, nr 3

199--216

EN

Advancements in technology and material sciences lead new solutions to be used in civil engineering. PolyUrethane Flexible Joints (PUFJ) and Fiber Reinforced PolyUrethanes (FRPU) are among those innovative solutions. PUFJ implemented systems comprise of seismic preventive buffer material between masonry infill walls and reinforced concrete (RC) frames, whereas FRPU solution is designed for covering the wall surfaces with thin composite strips. Both methods are primarily developed for increasing the ductility capacities of buildings while sustaining the overall structural strength without compromising on the safety of these systems against earthquakes. In this article, test results of the quasi-static cyclic experiments as well as dynamic tests on the shake tables including harmonic forces operating in resonance are presented. Moreover, numerical analyses are performed in order to comprehend the behavior of PUFJ implemented frames constituted with different masonry materials than above which are under various loading conditions. The outcomes confirmed the high efficiency of the proposed solutions, which at the same time meet the strict requirements of the modern seismic standards.

PL

Postępy w technologii i materiałoznawstwie prowadzą do nowych rozwiązań wprowadzanych w inżynierii lądowej. Wśród tych innowacyjnych rozwiązań znajdują się podatne złącza poliuretanowe (PUFJ) i poliuretany wzmocnione włóknami (FRPU). Systemy PUFJ instalowane są pomiędzy murowanymi ścianami wypełniającymi a ramami żelbetowymi jako anty-sejsmiczny element buforowy, natomiast systemy FRPU są przeznaczone do wzmacniania powierzchni ścian cienkimi pasami kompozytowymi. Obie metody zostały opracowane w celu zwiększenia ciągliwości budynków, przy jednoczesnym utrzymaniu ich ogólnej nośności, a tym samym w celu zwiększenia bezpieczeństwa użytkowania tych budynków w trakcie trzęsień ziemi. W artykule przedstawiono wyniki badań elementów w skali naturalnej pod quasi-statycznymi obciążeniami cyklicznymi oraz obciążeniami dynamicznymi na stole sejsmicznym i pod działaniem sił harmonicznych w rezonansie. Ponadto zostały przeprowadzone analizy numeryczne, mające na celu poznanie zachowania się podobnych konstrukcji z innymi materiałami murowymi współpracującymi z PUFJ, które poddane zostały różnym warunkom obciążenia. Wyniki potwierdziły wysoką skuteczność proponowanych rozwiązań, które jednocześnie spełniają surowe wymagania współczesnych norm sejsmicznych.

2

Floor acceleration amplification and response spectra of reinforced concrete frame structure based on shaking table tests and numerical study

Zou Xiaoguang, Yang Weiguo, Liu Pei, Wang Meng

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e156, 2023

EN

In the seismic design of acceleration-sensitive nonstructural components, floor acceleration response spectra are commonly selected for analysis, which has proven to be effective in practice. To accurately study the floor acceleration response spectrum of a reinforced concrete structure under earthquakes, a 3-story reinforced concrete frame structure designed based on Chinese codes was built and placed on a shaking table for testing to obtain actual floor acceleration response for investigation of spectral characteristics. In addition, a set of finite element models of reinforced concrete frame buildings were analyzed to better study the variation of floor acceleration peaks and response spectra with different modal periods. The results show that floor dynamic magnification is highly related to structural dynamic characteristics and building’s relative height. Obvious peaks are observed in the floor response spectrum, which correspond to the structural modal periods. The values of the spectra, particularly the peaks, show a strong correlation with the floor level and the damping ratios of nonstructural components. Based on the observations gained from shaking table tests and numerical study, a function for predicting the floor dynamic magnification factor and a method for generating the spectral amplification factor of the floor are proposed. Then the findings acquired from the test, numerical study, and existing methods were applied for the validation of the proposed methods. It is shown that the proposed floor dynamic magnification factor prediction function and spectral amplification factor prediction method are useful for the seismic design of nonstructural components in various reinforced concrete structures, taking into account the structural dynamic characteristics, the floor level, and the damping ratio of nonstructural components.

3

Effect of Link Beam Length of the Eccentric Bracing System on Seismic Rehabilitation of Weak Reinforced Concrete Frames

Niknam Touraj, Saberi Hamid, Saberi Vahid, Sadeghi Abbasali, Noroozinejad Farsangi Ehsan

Civil and Environmental Engineering Reports

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2022

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Vol. 32, no. 1

152--175

EN

In this study, a reinforced concrete (RC) reference specimen with compressive strength of 250 kg/cm2 and the weak RC specimen for seismic rehabilitation with compressive strength of 150 kg/cm2 were examined in two types of structures with 6 and 12-stories. The link beam lengths of 50, 80, and 100 cm have been used in 6 and 12-stories prototypes under the effect of 7 earthquake records. The nonlinear dynamic analyses are performed. Then, The behavior of the link beam depends on its length. For short link beam lengths, shear behavior is serious, then for medium lengths, shear-flexural behavior is important, and finally, long lengths will have flexural behavior for the beam. In eccentrically braced frames, the details of the link beam and the fit of the other members must be done in such a way as to ensure its proper ductility. According to the obtained results, the performance of short link beams is much better than long link beams, and short link beams provide more energy dissipation and, at the same time, more ductility. Therefore, in the design of the link beam, mainly the shear of the link beam is considered as a ductile component. The axial force in the link beam, which is due to the application of lateral load to the structure, reduces both the bending capacity and the inelastic deformation capacity of the link beam, so it can be explained that in steel eccentric braces, the link beam is symmetrical between the two main components of the brace and it can affect the strength of the structure against lateral loads.

4

Aspekty techniczne i ekonomiczne budowy górnych przejść dla zwierząt wykonanych z blach falistych oraz z prefabrykatów żelbetowych

Tomala Piotr, Mońka Michał

Materiały Budowlane

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2020

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nr 9

40--42

5

Seismic evaluation of deficient reinforced concrete weak beam-column joint frames

Rizwan Muhammad, Ahmad Naveed, Khan Akhtar Naeem, Fahad Muhammad

Archives of Civil Engineering

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2020

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Vol. 66, nr 4

429--451

EN

The use of old building design codes and improper execution of recent seismic design practices have caused large amount of substandard and vulnerable reinforced concrete RC building stock majority of which are built with weak beam-column joint connections defect (i.e. joint panel having no transverse reinforcement and built in low strength concrete). In order to understand the seismic response and damage behaviour of recent special moment resisting frame SMRF structures with the defect of weak beam-column joints, shake table tests have been performed on two 1:3 reduced scaled, two story RC frame models. The representative reference code design and weak beam-column joint frame models were subjected to uni-directional dynamic excitations of increasing intensities using the natural record of 1994 Northridge Earthquake. The input scaled excitations were applied from 5% to 130% of the maximum input peak ground acceleration record, to deformed the test models from elastic to inelastic stage and then to fully plastic incipient collapse stage. The weak beam-column frame experienced column flexure cracking, longitudinal bar-slip in beam members and observed with cover concrete spalling and severe damageability of the joint panels upon subjected to multiple dynamic excitations. The deficient frame was only able to resist 40% of the maximum acceleration input as compared to the code design frame which was able to resist about 130%. The seismic performance of considered RC frames was evaluated in terms of seismic response parameters (seismic response modification, overstrength and displacement ductility factors), for critical comparison.

6

Response of two-storey RC frame with special base-isolation using Ruaumoko 2D program

Alizada A. M., Hamid N. H., Yee P. T. L.

Archives of Civil Engineering

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2020

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Vol. 66, nr 4

287--301

EN

The control of structural vibrations due to ground motion can be done by the installation of a passive, active, and hybrid base isolation system. The primary function of the base isolator is to support the superstructure and provide huge horizontal flexibility and a long period of vibration. In this paper, a special HRDB base isolator is made from natural rubber with special elastic property and hardness. This base isolator is designed to support gravity loads of two-story RC building. The experimental hysteresis loop of this isolator is validated with analytical modeling hysteresis loop using Hysteresis program. The Bouc hysteresis rule was chosen as a model the hysteresis loop, and it is similar to experimental hysteresis loops. Later, a single bay two-story RC frame with a base isolation system was modeled using Ruaumoko 2D program subjected to three levels of earthquake excitations. After analyzing this frame under the 1994 Pacoima Dam Earthquake, the 1995 Kobe Earthquake and the 1940 El-Centro 1940 Earthquake. The numerical results show that this isolator is quite efficient in reducing the damage of structural and non-structural elements of the structure through minimizing inter-story drift, lateral displacement, and story acceleration. Therefore, this special HRDB based isolator is recommended to be used for low rise and medium-rise building in seismic regions.

7

Mitigation of blast load risk on reinforced concrete structures considering different design alternatives

Ibrahim Y. E., Almustafa M.

Archives of Civil Engineering

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2020

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Vol. 66, nr 3

225--238

EN

The purpose of this study is to investigate a structure’s response to blast loading when composite columns are used instead of conventional reinforced concrete (RC) cross sections and when a conventional structure is retrofitted with braces. The study includes conducting dynamic analyses on three different structures: a conventional reference RC structure, a modified structure utilizing composite columns, and a modified structure retrofitted with steel braces. The two modified structures were designed in order to investigate their performance when subjected to blast loading compared to the conventional design. During the dynamic analyses, the structures were exposed to simulated blast loads of multiple intensities using the finite-element modelling software, SeismoStruct. To evaluate their performance, the responses of the modified structures were analyzed and compared with the response of the conventional structure. It was concluded that both the structure with composite columns and the steel brace structure experienced less damage than the conventional model. The best performance was obtained through the steel brace structure.

8

Effect of setback irregularity location on the performance of RC building frames under seismic excitation

Mouhine Mohamed, Hilali Elmokhtar

Archives of Civil Engineering

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2020

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Vol. 66, nr 4

399--412

EN

The setback is a frequent type of irregularity expected in complex-shaped buildings. The main purpose of the present paper is to emphasize the influence of setback location on the performance of reinforced concrete building structures under seismic excitation. In this research study, 68 building models with setback values vary from 0.1 L to 0.5 L, located at various levels, are studied. Non-linear static (pushover) analyses were conducted. All building models are analyzed using a finite element calculation code. The outcomes show that setback irregularity location has a significant effect on the seismic behavior of the structure. Based on the regression analysis of the results obtained in the current study, a mathematical formula is proposed to quantify the effect of setback location on the performance of building structures. The results of this study would aid all professionals in the building sector to anticipate the response of these types of structures during the design phase.

9

Effects of staircase on the seismic behavior of RC moment frame buildings

Noorifard A., Tabeshpour M. R.

Architecture Civil Engineering Environment

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2018

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Vol. 11, no. 4

105--122

EN

Staircase has a potential to change the seismic behavior of structures, but it is often neglected during design. In this research, effects of staircase in 5 groups including 27 models have been studied. Results show that staircase constructed with the use of RC slab, performs as a K-shaped bracing in longitudinal direction and as an inclined shear wall in transverse direction, so in both directions structural stiffness increases, period and lateral displacement of structure decrease, but staircase constructed by means of stringer beam only acts as a bracing in longitudinal direction. Stiffness caused by small span, inclined RC slabs and perimeter infill walls of staircase, based on the staircase location and the number of structural bays could change mode shape and lead to torsion. Along ladder running, staircase leads shear force and bending moment of columns adjacent to the landing to increase, while the internal forces of others to decrease. The majority of adverse effects of the staircases can be prevented by isolating the staircase from master structure. In this case, only the changes in geometry of the structure due to location and dimension of staircase and arrangement of infill walls should be studied.

10

Symulacje numeryczne wyczerpania nośności ramy żelbetowej wypełnionej murem

Małyszko L., Bilko P.

Inżynieria i Budownictwo

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2016

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R. 72, nr 6

316--320

PL

Zilustrowano odpowiedź ramy obciążonej w płaszczyźnie wypełnionej murem. Zastosowano symulacje numeryczne, wykorzystując elementy skończone oraz mikro- i makromodelowanie. Przy mikromodelowaniu użyto interfejsów z systemu DIANA. Symulację z makromodelem przeprowadzono, wykorzystując autorski model konstytutywny. Przedstawiono niektóre cechy własnego modelu ortotropowego.

EN

The in-plane structural response of the frame infilled with masonry is illustrated via two numerical simulations using finite elements and the microand macromodelling. The DIANA interfaces dedicated for a masonry analysis is used in the micromodelling. The macromodelling simulation was carried out using the authors’ constitutive model which was implemented into the finite element system as the so-called user supplied subroutine. Some feature of the own orthotropic model are presented.

11

Modelowanie naroży ram żelbetowych w metodzie S-T

Bagrij P., Styś D.

Materiały Budowlane

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2015

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nr 6

76--77

PL

W artykule przedstawiono analizę naroży ram żelbetowych metodą Strut-and-Tie. Obliczenia przeprowadzono w programie CAST dla różnych modeli kratownicowych. Wyniki obliczeń porównano na podstawie kryterium energetycznego najmniejszej energii odkształcenia sprężystego prętów.

EN

Strut-and-Tie Modeling of reinforced concrete frame corner structures are shown. For calculation of different ST models are used program CAST. Results are compared with minimum strain elastic energy bars criterion.

12

Analiza ramy żelbetowej na obciążenia wyjątkowe według metody zastępczej ścieżki obciążenia

Kokot S.

Inżynieria i Budownictwo

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2012

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R. 68, nr 8

444-446

PL

Praca dotyczy zjawiska postępującego zawalenia, które może wystąpić, gdy np. element nośny ulegnie miejscowemu zniszczeniu. Żelbetowa rama została poddana eksperymentowi kolejnego niszczenia słupów w sposób quasi-statyczny. Podjęto próbę odpowiedzi na pytanie, co mogłoby się stać z tą konstrukcją, gdyby utrata słupów nastąpiła w bardzo krótkim czasie (np. podczas wybuchu).

EN

This paper deals with the progressive collapse of structures, which can occur when one load-bearing member fails locally. A reinforced-concrete frame was tested in-situ against successive quasi-static removal of columns. This work tries to answer the question: what would have happened to the frame if the columns had been removed in an abrupt way e.g. as in blasts.

13

Budowa wiaduktu kolejowego w Bydgoszczy metodą nasuwania poprzecznego

Zielonka P.

Inżynieria i Budownictwo

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2002

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R. 58, nr 6

306-308

PL

Konstrukcja wiaduktu ma postać ramy żelbetowej. Opisano technologię budowy obiektu. Zwrócono uwagę na zalety zastosowanej metody budowy, polegającej na przesunięciu wykonanych segmentów obiektu.

EN

Reinforced concrete frame structure built in segments was shiften across railway tracks and set up in position. This method of assembly occured as very positive and advantagous when comparing with traditional construction work.

14

Badania charakterystyk dynamicznych zarysowanych ram żelbetowych

Zembaty Z., Kowalski M.

Inżynieria i Budownictwo

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2001

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R. 57, nr 9

530-533

PL

Przedstawiono wyniki wstępnych analiz rezultatów eksperymentu dotyczącego wpływu zarysowania konstrukcji żelbetowych na ich charakterystyki dynamiczne. Dwie identyczne ramy żelbetowe poddano działaniu serii zwiększających się wymuszeń kinematycznych na stole wstrząsowym, powodujących stopniowo postępujące zarysowania. Podczas eksperymentu obserwowano zmiany częstotliwości rezonansowych i tłumienia w miarę rozwoju uszkodzeń.

EN

The paper presents selected early results of an experiment in which the effect of cracking on dynamic characteristics of reinforced concrete frames was studied in detail. Two identical RC frames have been subjected to a series of kinematic excitation with increasing intensities on shaking table, which caused progressive damage to the frames. Changes in natural frequencies and damping were observed.

15

Zbrojenie pętlowe monolitycznego węzła ramy żelbetowej

Czkwianianc A.

Inżynieria i Budownictwo

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2000

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R. 56, nr 8

429-432

PL

Podano wyniki badań skrajnego węzła monolitycznej wielokondygnacyjnej ramy żelbetowej. Badane elementy obejmowały odcinki słupów górnej i dolnej kondygnacji, węzeł i odcinek rygla. Stwierdzono, że nośność elementów zbrojonych pętlami jest mniejsza niż zbrojonych tradycyjnie. Potwierdzono jednak, że stosowanie zbrojenia pętlowego jest bezpieczne.

EN

It was shown that beam reinforcement anchored in a shape of loop in the joint of a RC frame do not always meat the condition of appriopriate anchorage. In the case analysed, for dimensional ratios assumed between beam and column and for the steel rebars dia. 14 and 18 mm the adequate anchorage of looped bars in the joint is not possible. An aplication of traditional anchorage of beam rebars in lower part of column was proved to be more advanageous.