scholarly journals Investigating the effects of structural pounding on the seismic performance of adjacent RC and steel MRFs

2020 ◽  
Vol 19 (1) ◽  
pp. 317-343
Author(s):  
F. Kazemi ◽  
M. Miari ◽  
R. Jankowski
Keyword(s):  
Reinforced Concrete ◽  
Near Field ◽  
Limit State ◽  
Steel Structures ◽  
Lateral Force ◽  
Separation Distance ◽  
Natural Period ◽  
Performance Levels ◽  
Structural Pounding ◽  
Adjacent Structures

AbstractAn insufficient separation distance between adjacent buildings is the main reason for structural pounding during severe earthquakes. The lateral load resistance system, fundamental natural period, mass, and stiffness are important factors having the influence on collisions between two adjacent structures. In this study, 3-, 5- and 9-story adjacent reinforced concrete and steel moment resisting frames (MRFs) were considered to investigate the collision effects and to determine modification factors for new and already existing buildings. For this purpose, incremental dynamic analysis was used to assess the seismic limit state capacity of the structures using a developed algorithm in OpenSees software including two near-field record subsets suggested by FEMA-P695. The results of this paper can help engineers to approximately estimate the performance levels of MRFs due to pounding phenomenon. The results confirm that collisions can lead to the changes in performance levels, which are difficult to be considered during the design process. In addition, the results of the analyses illustrate that providing a fluid viscous damper between adjacent reinforced concrete and steel structures can be effective to eliminate the sudden changes in the lateral force during collision. This approach can be successfully used for retrofitting adjacent structures with insufficient in-between separation distances.

scholarly journals Fragility Analysis of Structural Pounding Between Adjacent Structures Arranged in Series With Various Alignment Configurations Under Near-field Earthquakes

2022 ◽  
Author(s):  
Fahimeh Ebrahimiyan ◽  
Mohammad Ali Hadianfard ◽  
Hosein Naderpour ◽  
Robert Jankowski
Keyword(s):  
Fragility Curves ◽  
Near Field ◽  
Limit State ◽  
Failure Criteria ◽  
Structural Performance ◽  
Structural Pounding ◽  
Critical Situation ◽  
Adjacent Structures ◽  
Moment Resisting ◽  
In Series

Abstract A major cause of local to total damages is related to structural pounding in a large number of past earthquakes. In general, these collisions take place as a result of differences in the dynamic characteristics of the colliding structures. To acquire a better perception of the behavior of structures, in this paper, three structures featuring different heights are modeled in series and with various configurations next to each other in OpenSees. To determine the collision effects of the structures, three different configurations of 4-, 8- and 12-story adjacent reinforced concrete special moment resisting frames were considered. Then, by conducting an incremental dynamic analysis, their structural seismic limit state capacities were assessed via 20 near-field record subsets recommended by FEMA-P695. At last, for the above adjacent buildings with various separation distances and configurations, the fragility curves were determined, and the probability of exceedance from the primary Hazus-MH failure criteria was estimated. In addition, the results were compared with those obtained when this phenomenon did not take place for buildings to have a better perception of the pounding phenomenon. The results of the analyses show that arranging adjacent structures in series greatly affects the collapse capacities of the colliding structures. In addition, in the case when the shorter structure is placed in the middle of two taller structures, it results in the most critical situation among all configurations, and in this case, a higher reduction is observed in the structural performance levels.

Seismic response of structural walls: recent developments

2001 ◽  
Vol 28 (6) ◽  
pp. 922-937 ◽  
Author(s):  
T Paulay
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Seismic Design ◽  
Limit State ◽  
Lateral Force ◽  
Structural Walls ◽  
Structural Class ◽  
Response Component ◽  
Displacement Ductility ◽  
Ductility Capacity

It is postulated that for purposes of seismic design, the ductile behaviour of lateral force-resisting wall components, elements, and indeed the entire system can be satisfactorily simulated by bilinear force–displacement modeling. This enables displacement relationships between the system and its constituent components at a particular limit state to be readily established. To this end, some widely used fallacies, relevant to the transition from the elastic to the plastic domain of behaviour, are exposed. A redefinition of stiffness and yield displacement allows more realistic predictions of the important feature of seismic response, component displacements, to be made. The concepts are rational, yet very simple. Their applications are interwoven with the designer's intentions. Contrary to current design practice, whereby a specific global displacement ductility capacity is prescribed for a particular structural class, the designer can determine the acceptable displacement demand to be imposed on the system. This should protect critical components against excessive displacements. Specific intended displacement demands and capacities of systems comprising reinforced concrete cantilever and coupled walls can be estimated.Key words: ductility, displacements, reinforced concrete, seismic design, stiffness, structural walls.

Investigation on Damage-Involved Structural Response of Colliding Steel Structures during Ground Motions

2016 ◽  
Vol 713 ◽  
pp. 26-29 ◽  
Author(s):  
Barbara Sołtysik ◽  
Tomasz Falborski ◽  
Robert Jankowski
Keyword(s):  
Dynamic Properties ◽  
Ground Motions ◽  
Structural Response ◽  
Steel Structures ◽  
Separation Distance ◽  
Shaking Table ◽  
Engineering Structures ◽  
Positive Role ◽  
Acceleration Time Histories ◽  
Adjacent Structures

Earthquakes are the most unpredictable damaging loads which can affect civil engineering structures. Due to insufficient separation distance between adjacent structures with different dynamic properties, structural collisions may occur during ground motions. Although the research on structural pounding has recently been much advanced, the studies have mainly been conducted for concrete structures. The aim of this paper is to show the results of experimental investigation, focused on dynamic behaviour of closely-separated three models of steel structures which have been subjected to damaging earthquake excitations. The study was performed using three models of steel towers with different dynamic parameters and various distances between the structures. The acceleration time histories of the Kobe and the Northridge earthquakes were applied as the seismic excitation. The unidirectional shaking table, located at the Gdansk University of Technology (Poland), was used in the experimental study. The results have confirmed that collisions may lead to the increase in the structural response, although they may also play a positive role, depending on the size of the separation gap between the structures.

scholarly journals Effects of Near-fault Strong Ground Motions on Probabilistic Structural Seismic-induced Damages

2019 ◽  
Vol 5 (4) ◽  
pp. 796-809
Author(s):  
Farzad Mirzaie Aminian ◽  
Ehsan Khojastehfar ◽  
Hamid Ghanbari
Keyword(s):  
Fragility Curves ◽  
Ground Motions ◽  
Near Field ◽  
Limit State ◽  
Far Field ◽  
Seismic Performance Assessment ◽  
Limit States ◽  
Performance Levels ◽  
Strong Ground Motions ◽  
Strong Ground

Seismic fragility curves measure induced levels of structural damage against strong ground motions of earthquakes, probabilistically. These curves play an important role in seismic performance assessment, seismic risk analysis and making rational decisions regarding seismic risk management of structures. It has been demonstrated that the calculated fragility curves of structures are changed while the structures are excited by near-field strong ground motions in comparison with far-field ones. The objective of this paper is to evaluate the extents of modification for various performance levels and variety of structural heights. To achieve this goal, Incremental Dynamic Analysis (IDA) method is applied to calculate seismic fragility curves. To investigate the effects of earthquake characteristics, two categories of strong ground motions are assumed through IDA method, i.e. near and far-field sets. To study the extent of modification for various heights of structures, 4 – 6 and 10 stories moment-resisting concrete frames are considered as case studies.  Furthermore, to study the importance of involving near-field strong ground motions in seismic performance assessment of structures, the damage levels are considered as the renowned structural performance levels (i.e. Immediate Occupancy, Life Safety, Collapse Prevention and Sidesway Collapse). Achieved results show that the fragility curve of low-rise frame (i.e. 4-story case study) for IO limit state presents more probability of damage applying near-fault sets in comparison with far-fault set. Investigating fragility curves of the other performance levels (i.e. LS, CP and Collapse) and the higher frames, a straightforward conclusion, regarding probability of damage. To achieve the rational results for the higher frames, mean annual frequency of exceedance (MAFE) and probability of exceeding limit states in 50 years are calculated. MAFE is defined as the integration of structural fragility curve over seismic hazard curve. According to the achieved results for 6-story frame, if the structure is excited by near-field strong ground motions the probability of exceedance for LS, CP and collapse limit states in 50 years will be increased up to 11%, 2.4%, 0.7% and 0.4% respectively, comparing with the calculated probabilities while far-field strong ground motions are applied. On the other hand, while the 10-story case study is excited by near-field strong ground motions, the exceedance probability values for mentioned limit states decreases up to 20%, 5%, 4% and 4%, respectively. Consequently, it can be concluded that the lower is the height of the structure, the more will be the increment of probability of damage in the near-field conditions. Furthermore, this increment is much more for IO limit state in comparison with other limit states. These facts can be applied as a precaution for seismic design of low-rise structures, while they are located at the vicinity of active faults.

Combined Reinforced Concrete Columns Strengthening with Steel Clipping and Concrete Surfacing

2021 ◽  
pp. 11-22
Author(s):  
Ю. Г. Москалькова ◽  
С. В. Данилов ◽  
В. А. Ржевуцкая
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Limit State ◽  
Concrete Columns ◽  
Ultimate Limit State ◽  
Concrete Core ◽  
Reinforced Concrete Columns ◽  
Entire Height ◽  
Complex Structural ◽  
Ultimate Limit

Постановка задачи. Исследуется метод усиления железобетонных колонн устройством стальной обоймы с обетонированием, который позволяет восстанавливать эксплуатационные показатели колонн, имеющих значительные дефекты и повреждения. Предпосылкой настоящих исследований явилось предположение о том, что усиление стальной обоймой с обетонированием является эффективным способом повышения несущей способности железобетонных колонн, причем вариант приложения нагрузки - только на бетонное ядро или ко всему сечению - существенно на эффективность усиления не влияет. В связи с этим целью исследования является определение необходимости устройства стального оголовка и включения в работу ветвей стальной обоймы при условии обетонирования стержня колонны по всей высоте. Результаты и выводы. Рациональным признан способ передачи нагрузки только на бетонное ядро усиленных колонн, поскольку устройство оголовка стальной обоймы требует применения сложных конструктивно-технологических решений, но при этом дополнительно увеличивает несущую способность незначительно (согласно проведенным исследованиям менее чем на 10 %). Ввиду отсутствия необходимости устройства конструкций стального оголовка снижаются трудоемкость и сроки производства работ по усилению колонн. Statement of the problem. The method of strengthening reinforced concrete columns with a steel clipping and the concrete surfacing is investigated. This method allows one to repair the columns with significant defects and damage. The prerequisite for this study was the assumption of strengthening with a steel clipping and the concrete surfacing is an effective way to increase the ultimate limit state of reinforced concrete columns, furthermore, the option of applying the load (only to the concrete core or to the entire section) does not significantly affect the strengthening effectiveness. In this regard, the purpose of the investigation was to identify the need to include the steel jacketing in the work, on the condition the column is coated with concrete along with the entire height. Results and conclusions. The load transfer method only to the concrete core of the strengthened columns is recognized as rational since the device of the steel clipping head requires the use of complex structural and technological solutions, but at the same time additionally increases the ultimate limit state insignificantly (according to the studies by less than 10 %). Due to the absence of the need to establish structures of the steel jacketing head, the labor intensiveness and terms of work production on strengthening the columns are reduced.

ESTIMATION OF THE FAILURE PROBABILITY OF A REINFORCED CONCRETE BEAM LYING ON A STOCHASTIC ELASTIC BASE WITH TWO PRESSURE COEFFICIENTS, ON AN INCLINED SECTION FROM THE LATERAL FORCE

2021 ◽  
Vol 93 (1) ◽  
pp. 16-25
Author(s):  
P.D. DEMINOV ◽  
Keyword(s):  
Reinforced Concrete ◽  
Failure Probability ◽  
Rational Functions ◽  
Lateral Force ◽  
Elastic Base ◽  
Strength Properties ◽  
Reinforced Concrete Beams ◽  
Total Probability ◽  
Limit States ◽  
Random Load

The estimate of failure probability on the inclined section from the action of transverse forces, as well as the total probability of the limit States of reinforced concrete beams with probabilistic strength parameters lying on an elastic Foundation model V.Z. Vlasov-P.L. Pasternak, possessing stochastic properties. Probabilistic characteristics of the transverse force and its distribution density are constructed for a Foundation beam resting on an elastic base with two random characteristics, loaded with a quasi-stationary random load, taking into account the probabilistic nature of the strength properties of concrete and reinforcement. It is shown that if the spectral densities of the bed and load coefficients are fractional rational functions, the deflection correlation functions and, accordingly, the deflection variance are calculated using the residue theory.

scholarly journals Behavioural Study of Shear Wall with Correlational to Bracing under Seismic Loading

2018 ◽  
Vol 65 ◽  
pp. 08008
Author(s):  
Syed Muhammad Bilal Haider ◽  
Zafarullah Nizamani ◽  
Chun Chieh Yip
Keyword(s):  
Reinforced Concrete ◽  
Lateral Displacement ◽  
Limit State ◽  
Shear Wall ◽  
Design Tool ◽  
Base Shear ◽  
Building Model ◽  
High Rise ◽  
Finite Element Software ◽  
Seismic Vibrations

The reinforced concrete structures, not designed for seismic conditions, amid the past earthquakes have shown us the significance of assessment of the seismic limit state of the current structures. During seismic vibrations, every structure encountered seismic loads. Seismic vibrations in high rise building structure subjects horizontal and torsional deflections which consequently develop extensive reactions in the buildings. Subsequently, horizontal stiffness can produce firmness in the high rise structures and it resists all the horizontal and torsional movements of the building. Therefore, bracing and shear wall are the mainstream strategies for reinforcing the structures against their poor seismic behaviours. It is seen before that shear wall gives higher horizontal firmness to the structure when coupled with bracing however it will be another finding that in building model, which location is most suitable for shear wall and bracing to get better horizontal stability. In this study, a 15 story residential reinforced concrete building is assessed and analyzed using building code ACI 318-14 for bracing and shear wall placed at several different locations of the building model. The technique used for analysis is Equivalent Static Method by utilizing a design tool, finite element software named ETABS. The significant parameters examined are lateral displacement, base shear, story drift, and overturning moment.

An Adaptive Loading Test on Collapse Mechanism Formation of Multi-Story Steel Frames Subjected to Uncertain Lateral Load Pattern

2007 ◽  
Vol 345-346 ◽  
pp. 1169-1172
Author(s):  
Kenichi Ohi ◽  
Jae Hyouk Choi
Keyword(s):  
Limit State ◽  
Lateral Force ◽  
Collapse Mechanism ◽  
Loading Test ◽  
Design Point ◽  
Steel Moment Resisting Frames ◽  
Random Combination ◽  
Moment Resisting ◽  
Earthquake Load ◽  
Load Pattern

An adaptive loading system is developed to examine a design point of multi-story steel test frames subjected to uncertain load pattern. Lateral loads are given as a random combination of basic load patterns, and the system drives a test frame to the most likely failure situation. Two-story steel moment resisting frames are tested considering a failure mechanism formation of plastic collapse as a tentative limit state. A random 2-dof lateral force is given by a random combination of two basic load patterns, which are arranged to represent elastic earthquake load effects. Hybrid design point search or adaptive loading tests on the 2-story frame are performed, and the detected likely failure mechanisms are compared with the results of pseudo-dynamic response tests to deterministic excitations.

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