scholarly journals Irregularity of the Distribution of Masonry Infill Panels and Its Effect on the Seismic Collapse of Reinforced Concrete Buildings

2021 ◽  
Vol 11 (18) ◽  
pp. 8691
Author(s):  
Juan Carlos Vielma ◽  
Roberto Aguiar ◽  
Carlos Frau ◽  
Abel Zambrano
Keyword(s):  
Reinforced Concrete ◽  
Structural Response ◽  
Practical Reasons ◽  
Reinforced Concrete Buildings ◽  
Masonry Infill ◽  
Concrete Buildings ◽  
Infill Panels ◽  
Open Plan ◽  
Collapsed Buildings ◽  
The City

On 16 April 2016, an earthquake of Mw 7.8 shook the coast of Ecuador, causing the destruction of buildings and a significant number of casualties. Following a visit by the authors to the city of Portoviejo during the debris removal and recovery stage, it was noted that several reinforced concrete buildings located on corners had collapsed in the central part of the city. These buildings were characterized by the presence of masonry at the edges of the buildings but not between the two mostly open-plan facades on the corner for practical reasons. This article reviews the effect of masonry infill panels on the seismic response of reinforced concrete structures. For this, a model that contains the geometric and mechanical characteristics typical of collapsed buildings was generated and subjected to nonlinear analysis, with both static and dynamic increments. The results show the clear influence of the masonry infill panels on the structural response through the torsional behavior that is reflected in the evolution of the floor rotations. Finally, dynamic incremental analysis is used to obtain the collapse fragility curve of the building, and a new damage measure based on floor rotations is proposed.

scholarly journals Impact of Revised Code NBC105 on Assessment and Design of Low Rise Reinforced Concrete Buildings in Nepal

2021 ◽  
Vol 16 (1) ◽  
pp. 1-5
Author(s):  
Jagat K. Shrestha ◽  
Nirajan Paudel ◽  
Bishal Koirala ◽  
Binod R. Giri ◽  
Adarsha Lamichhane
Keyword(s):  
Reinforced Concrete ◽  
Residential Buildings ◽  
Structural Response ◽  
Building Codes ◽  
Seismic Load ◽  
Base Shear ◽  
Reinforced Concrete Buildings ◽  
Concrete Buildings ◽  
The Government ◽  
The Impact

Gorkha Earthquake in 2015 has impacted considerably in the design and construction of buildings in Nepal. Strength and Safety of life and constructions have become the prime concerns of the government and the public. Regulation is required to achieve the strength and safety in the constructions. Hence, a need for revision of building codes has been felt and Nepal Building Code, NBC105 has been revised. This paper presents the impact of the revised code on seismic load estimation for low rise reinforced concrete buildings. For the assessment of the impact linear and non- linear static and linear dynamic analysis of reinforced concrete residential buildings of two storey and four Storey has been taken subjected to Indian Standard Codes IS 1893: 2002, IS 1893:2016, Nepal Building Codes NBC 105: 1994 and NBC 105: 2020. The buildings were modeled and analyzed in SAP2000. The response of the buildings such as time period, base shear, drifts, and storey forces from the application of the four codes was compared. The comparison of the results shows that the structural response of the building under the revised NBC105:2020 is 60% to 65% higher compared to the previous code NBC105:1994.

Response of earthquake-resistant reinforced-concrete buildings to blast loadingThis article is one of a selection of papers published in the Special Issue on Blast Engineering.

2009 ◽  
Vol 36 (8) ◽  
pp. 1378-1390 ◽  
Author(s):  
Murat Saatcioglu ◽  
Togay Ozbakkaloglu ◽  
Nove Naumoski ◽  
Alan Lloyd
Keyword(s):  
Reinforced Concrete ◽  
Blast Resistance ◽  
Structural Parameters ◽  
Progressive Collapse ◽  
Structural Response ◽  
Charge Weight ◽  
Blast Loads ◽  
Reinforced Concrete Buildings ◽  
Collapse Potential ◽  
Concrete Buildings

Recent bomb attacks on buildings have raised awareness about the vulnerability of structures to blast effects. The resiliency of structures against blast-induced impulsive loads is affected by structural characteristics that are also important for seismic resistance. Deformability and continuity of structural elements, strength, stiffness, and stability of the structural framing system and resistance to progressive collapse are factors that play important roles on the survivability of buildings under both blast and seismic loads. The significance of these structural parameters on blast resistance of reinforced concrete buildings is assessed through structural analysis. Both local element performance and global structural response are considered while also assessing the progressive collapse potential. The buildings under investigation include 10-storey moment resisting frames with or without shear walls. The blast loads selected consist of different charge-weight and standoff distance combinations. The results are presented in terms of ductility and drift demands. They indicate improved performance of seismic-resistant buildings when subjected to blast loads, in terms of local column performance, overall structural response, and progressive collapse potential.

Earthquake Disasters and Earthquake Engineering in Japan

2006 ◽  
Vol 1 (1) ◽  
pp. 26-45
Author(s):  
Syun'itiro Omote ◽  
Keyword(s):  
Reinforced Concrete ◽  
Earthquake Engineering ◽  
The Philippines ◽  
Economic Losses ◽  
Reinforced Concrete Buildings ◽  
Concrete Buildings ◽  
Earthquake Force ◽  
San Fernando ◽  
The City ◽  
Heavy Damage

Major earthquakes occur somewhere every year with accompanying devastations. For example, the center of the city of Managua was destroyed completely in December 1972 with the loss of more than 15,000 lives. Government buildings also did not escape destruction which brought about a paralysis in Governmental functioning for a short time. In April of the same year, in Iran an earthquake of magnitude 6.9 attacked the town of Ghir causing the loss of 5,000 lives. Large earthquakes accompanied by large losses of life occur frequently in Iran. Another type of earthquake destruction was caused in Peru in 1970 resulting in the loss of more than 50,000 lives under a huge mud slide that accompanied the big earthquake. In 1971, the San Fernando Earthquake, in the U.S.A. caused very heavy damage to the modern reinforced concrete buildings and highway overpasses calling serious attention to the devastation which might be brought about in modern large cities if a destructive earthquake should occur. The figure for lives lost by the San Fernando earthquake was small, assisted by the extremely lucky time of the occurrence of the earthquake at 6 A.M., when daily activity had not yet started. In 1968 an earthquake occurred in the city of Manila, the Philippines, crashing down completely an apartment house burying 260 people under the debris together with the destruction of many large reinforced concrete buildings. In the same year another big earthquake occurred in the northern part of Japan causing very heavy damage to the reinforced concrete buildings, all of which had been designed to resist earthquake force according to the Japanese regulations for antiseismic design. Repeated destruction of reinforced concrete buildings by earthquakes in recent years has caused a questioning of construction engineering. Such heavy destruction as experienced by reinforced concrete buildings in this earthquake (buildings which were designed and constructed under the antiseismic regulations) raised serious discussions among Japanese earthquake engineers which call for urgent studies. In Table 1 is shown a list of earthquakes that have resulted in heavy destruction since 1960. It may be surprising to find that about 20 earthquakes are included in the table showing that an average of three earthquakes of a destructive nature occurs somewhere on earth every two years. According to UNESCO statistics, between 1926 and 1950 over 350,000 people were killed by earthquakes, and the damage to buildings and public works totaled nearly $ 10,000 million. In proportion to the spread of urban civilization throughout the world, the toll taken by these destructive earthquakes has been steadily increasing and will increase more rapidly in the future. The only way to ensure against these substantial economic losses is to design and build, and to strengthen existing buildings, in such a way that the structure will resist the seismic forces to be expected in each area.

scholarly journals Seismic Vulnerability and Risk of Losses Case Study Center of the City of Azogues

2021 ◽  
Vol 1203 (3) ◽  
pp. 032124
Author(s):  
Carlos Julio Calle Castro ◽  
Juan Sebastián Maldonado Noboa ◽  
Luis Mario Almache Sánchez
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Inelastic Behavior ◽  
Reinforced Concrete Buildings ◽  
Concrete Buildings ◽  
Capacity Curves ◽  
Performance Point ◽  
The City

Abstract Ecuador is located in the Pacific Ring of Fire, a country with high risk and seismic sensitivity, evidenced by the 6.8-degree earthquake in Ambato in 1949, which left approximately 6000 dead, the 7.8-degree earthquake in Manabí and Esmeraldas in the year 2016 with 663 victims and 29672 buildings without the possibility of use. Currently there is a problem about seismic performance in reinforced concrete buildings, since many were built with old regulations; so, it is necessary to assess their vulnerability. Quito, Guayaquil and Cuenca, large cities in Ecuador, have formal studies of seismic vulnerability, mostly carried out by university students and teachers. In contrast, most small cities do not have these studies; or, they need to be updated to validate their results. This is the case of the city of Azogues. The objective of this research is to evaluate the vulnerability of structures using the Hazus methodology, adapted to Ecuador, in the downtown area of the city of Azogues, in structures located around the Central Park, to establish the seismic performance in reinforced concrete buildings. The Hazus methodology, which determines the vulnerability of buildings from fragility curves, which are entered with inputs as the capacity, performance level and drift curves calculated through Ecuadorian models. The capacity curves, depending on various aspects such as: the material, number of floors, spans between columns, among others; they vary from building to building. In this sense, capacity curves were defined for sets of buildings with similar characteristics, coinciding with the Hazus methodology. The performance levels and the displacements were calculated with the ETABS computer package. For fragility curves, the model that most real simulates the response of a structure is the non-linear analysis, because it considers the decrease in stiffness in columns and beams, as well as the deterioration of the properties of the materials. In this sense, there are fragility curves of Ecuadorian buildings for four levels. The earthquake readings enable the construction of a demand spectrum, which, when contrasted with the capacity spectrum, leads to the performance point. Its position sometimes varies per the elastic demand spectrum, which is diminished by its inelastic behavior. As the demand spectrum decreases, the damage will increase. Once the coordinates of the performance point are known, the fragility curves are used; and, the possible damages are defined, quantifying them in percentage.

Dynamic Characteristics of Multi-Story Reinforced Concrete Buildings

2016 ◽  
Vol 249 ◽  
pp. 235-240 ◽  
Author(s):  
Jónas Thór Snaebjornsson ◽  
Eythor Rafn Thorhallsson
Keyword(s):  
Reinforced Concrete ◽  
Natural Frequencies ◽  
Structural Parameters ◽  
Structural Response ◽  
Design Guidelines ◽  
Reinforced Concrete Buildings ◽  
Structural Behaviour ◽  
Measurement Systems ◽  
Concrete Buildings ◽  
International Data

Having a realistic estimate of structural parameters, such as natural frequency and damping is important for design purposes. In this study, available wind and earthquake induced acceleration data from four multi-story reinforced concrete buildings are utilized to examine structural behaviour and system parameters. The buildings measurement systems are described and the recorded structural response data presented. The data stems from two different sources of excitation, i.e. wind and earthquake, and are recorded for various excitation levels and environmental conditions. System identification analyses of the buildings are carried out applying previously verified parametric methods to the recorded data. The natural frequencies and critical damping ratios established from the recordings are compared to values estimated using design guidelines and international data compilations for reinforced concrete structures of similar type. Considerable variability is discovered between the different estimation formulas and the observed natural frequencies of the buildings are found to lie at the upper limit of the prediction formula.

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