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CONTENTS
Volume 28, Number 2, February 2025
 

Abstract
This paper investigates the cyclic performance of Y-braced steel frames (YSFs) equipped with a block slit damper (YSF-BSD). On the basis of the validation of an existing test on a Y-braced steel frame, the finite element (FE) model of YSF-BSD was developed. Then, parametric analyses are conducted to analyse the effects of the material strength, height-to-width ratio, height-to-thickness ratio, number and section shrinkage ratio of steel strips on the seismic performance and stiffness distributions of YSF-BSDs. The results show that (1) the ductility of YSF-BSD increases by 59.57% compared with that of conventional YSF, but the lateral loading capacity decreases by approximately 3.26%; (2) according to the parametric analysis results, the number of steel strips is suggested to be 4~5, the height-width ratio is 3~3.6, the height-thickness ratio should be larger than 3.3, and the section shrinkage ratio of steel strips should be 0.4~0.5; (3) a theoretical method is developed to determine the lateral stiffness distributions of YSF and BSDs, and the maximum error is less than 19.49%, most of which are less than 10%, and the lateral stiffness ratio of BSD to YSF is suggested to be 10~15 considering the ductility and deformation capacity of YSF-BSD.

Key Words
block slit damper (BSD); cyclic performance; parametric analysis; stiffness distribution; Y-braced steel frame

Address
Chen Zhou, Liqiang Jiang and Lizhong Jiang: School of Civil Engineering, Central South University, Changsha 410075, China
Hua Yang: 1) School of Civil Engineering, Central South University, Changsha 410075, China, 2) School of Civil Engineering, Chang'an University, Xi'an, 710061, China
Bing Tian, Yang Wu and Zhen Zhao: 3rd Construction Co. Ltd. of China Construction 5th Engineering Bureau, Changsha 410004, China
Hong Zheng: School of Civil Engineering, Chang'an University, Xi'an, 710061, China
Xiaodong Xu: Power China Northwest Engineering Co. Ltd, Xi'an, 710075, China

Abstract
Iran, a densely populated country, is geographically located in a very high-seismicity region and requires detailed seismic hazard/risk analyses, especially for her strategic population/industrial areas, to provide vital information for decision makers to take effective risk reduction measures. For the first time, this paper makes use of accurate updated methods, recent population/housing census statistics and socio-economic data to analyze the seismic risk considering different uncertainties for buildings with different structural systems in Yasouj city. The descriptive/quantitative information of the buildings and active faults of this city is implemented in GIS, probabilistic risk analyses are performed and hazard curves and design spectrum are produced for four different vulnerability levels for the site of the research area using the capabilities of the OpenQuake Software. Results show that designing new strong structures and retrofitting the existing buildings in the region is very important to prevent high economic, social and human losses.

Key Words
earthquake damage; probabilistic seismic hazard analysis; probabilistic seismic risk analysis; vulnerability analysis

Address
Ali Sadeghi and Farshid Fathi: Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
Abdolreza S. Moghadam: 1) Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran, 2) Structural Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran

Abstract
On February 6, 2023, two major earthquakes occurred in southern Turkey with an interval of 9 hours. The two earthquakes that occurred are two major earthquakes that are individually important. If it had occurred in different regions over a longer period, it would have entered the literature as two separate earthquakes. These two major earthquakes, centered in Pazarcik (7.7 Mw) and Elbistan (7.6 Mw), affected a total of 11 cities in the south and east of the country, and approximately 14 million people living in these cities were directly damaged by the earthquake. According to the official data, the loss of life due to the earthquake is around 50000. After the earthquake that caused such great losses, the region became the focus of researchers. However, studies focus on structural damage, considering the earthquake's first effect. Although not directly caused by the first movement after the earthquake, secondary effects resulting from the earthquake or the physical characteristics of the region cause significant damage, although not as much as the primary effects. Secondary effects such as liquefaction, fire, landslide, change in water level, change in water quality, surface fractures, and tsunami should be examined and prevented from occurring in these situations as well as buildings affected by earthquakes. Within the scope of this study, the type and distribution of secondary effects in the cities affected by the Kahramanmaraş earthquakes were examined. Secondary effects were intense in the cities of Hatay, Kahramanmaraş, Adiyaman and Malatya. In addition to the distribution of secondary effects, its relationship with the rate of structural damage and the economic costs it causes were examined. Considering the results, the incidence of secondary effects also increases in cities with a high rate of structural damage. In addition, the effect of secondary effects on direct economic costs is around 30%. The economic cost of the Kahramanmaraş earthquakes due to secondary effects has been calculated as approximately 17 billion dollars. In addition to the primary effects of earthquakes, their secondary effects should also be considered. This will give sensitivity to the predictions made in terms of minimizing earthquake-related damage.

Key Words
earthquake observation; economic losses; Kahramanmaras earthquakes; secondary earthquake effects

Address
Department of Civil Engineering, Faculty of Engineering and Architecture, Bingol University, Bingol, Turkey

Abstract
The recent increase in earthquakes in Korea, including those in Kyeong-Ju and Pohang, has caused significant damage and landslides in surrounding areas. This study investigated earthquake-induced landslides to identify ways to reduce the risk of damage caused by slope instability. Landslide risk was assessed through finite element analysis of the slope factor of safety using topographic and geological data of the Pohang region combined with actual earthquake observations. A path was established to evaluate the slope stability and hazards at the end of the slope. The results of this study were compared with the landslide hazard map and showed good agreement, validating the accuracy of the model. In addition, the analysis of different paths provided quantitative and precise information about slope boundaries. Landslide hazards increase under earthquake conditions. Obtaining a quantitative factor of safety provides valuable information for designing slopes and adjacent areas.

Key Words
earthquakes; finite element modeling; landslides; seismicity; slopes-stabilization

Address
Zheongzun Yi: Interdisciplinary Program in Landscape Architecture, Seoul National University, Seoul 08826, Republic of Korea
Junsuk Kang: 1) Interdisciplinary Program in Landscape Architecture, Seoul National University, Seoul 08826, Republic of Korea, 2) Department of Landscape Architecture and Rural Systems Engineering, Seoul National University, Seoul 08826, Republic of Korea, 3) Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea, 4) Interdisciplinary Program in Urban Design, Seoul National University, Seoul 08826, Republic of Korea, 5) Transdisciplinary Program in Smart City Global Convergence, Seoul National University, Seoul 08826, Republic of Korea

Abstract
In order to study the fragility of a reinforced concrete (RC) frame structure subjected to multi-dimensional earthquakes of different-duration, 19 sets of long and short-duration ground motions are assembled by using "spectrally equivalent". Incremental dynamic analysis (IDA) is used to analyze the fragility of an RC frame structure. The IDA curve and percentile curves for two-dimensional and three-dimensional long- and short-duration ground motions are obtained. Analyzing the response of a structure subject to ground motions with different dimensions and durations using Sa(T1,0.05) as a ground motion intensity parameter, a structural seismic probability demand model is established, and different evaluation indicators are used to analyze the failure probabilities of the structure. The results show that when subjected to long-duration ground motion, the structure is more prone to collapse. Compared with two-dimensional ground motion, the effect of long-durations has a slightly advance on structural damage subjected to three-dimensional ground motion. Different fragility evaluation measures can be used to evaluate the seismic performance of the structure, which can be used in engineering design.

Key Words
fragility analysis; frame structure; long- and short-duration ground motion; multi-dimensional ground motion; spectral matching

Address
School of Civil Engineering and Geomatics, Southwest Petroleum University, Chengdu, No.8, Xindu Street, Xindu District, Chengdu, China

Abstract
This paper examines the impact of masonry infill walls on the seismic performance of reinforced concrete frames with setbacks in elevation. Several setback Reinforced Concrete Moment Resisting Frames (RCMRFs), both with and without Masonry Infill Walls (MIWs), are designed and subjected to nonlinear dynamic analysis. The nonlinear responses of the structures are assessed using acceptance criteria. Including masonry walls in the frame modeling for this research reduced the maximum drift by 40%, the maximum plastic rotation of columns by 55%, and the maximum plastic rotation of beams by 37%. These results indicate that masonry walls can significantly enhance the seismic performance of the setback concrete frames, as well as concrete beams and columns. In some of the studied irregular frames, the maximum drift values at the Life Safety (LS) level exceed the limit of 2% when the effects of infill walls are not considered. However, these values fall within the allowable range when the effects of the infill walls are included. Additionally, the plastic rotations of certain columns in irregular frames without masonry infill walls surpass the LS allowable limit of 0.016 radians. By accounting for the effects of the infill walls, these rotations are reduced to acceptable levels in nearly all columns. Furthermore, the results show that in the upper-story beams of most irregular frames, the plastic rotation values exceed the allowable limits, even when the effects of infill walls are considered. Consequently, the local life safety performance criteria for these beams are not met.

Key Words
masonry infill wall; nonlinear time-history analysis; RC buildings; seismic performance; setbacks

Address
Meisam Vahed: Department of Civil Engineering, University of Kurdistan, Sanandaj, Iran
Alireza Habibi: Department of Civil Engineering, Shahed University, Tehran, Iran

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