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Article
Code: E118201303002
First author: WANG Tao
First author's unit: key laboratory of earthquake engineering and engineering vibration,institute of engineering mechanics,cea,
Other author:

ZHANG Yongqun: Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, CEA, Harbin 150080 China

JIN Bo: Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, CEA, Harbin 150080 China

KONG Ziang: Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, CEA, Harbin 150080 China

LEI Yuande: Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, CEA, Harbin 150080 China

Published year: 2013
Roll: 33
Issue: 3
Page: 9-19
About the Journal
Title: Earthquake Engineering and Engineering Vibration
Subject: Geophysics
Founded: 1981
ISSN: 1000-1301
CN: 23-1157/P
Publisher:
Editor-in-chief:
Long Abstract
Abstract

Abstract:

Objectives:
The Ms7.0strong earthquake hit Lushan county, Sichuan province, on April 20th, 2013, which caused significant human casualties and economic loss. Based on the field investigation, this paper systematically summarized the seismic damage patterns of masonry residential buildings, and evaluated the seismic fortification level of local masonry residential buildings after Wenchuan earthquake.

Methods:
The data of this paper is collected by means of field investigation. The authors immediately entered the heavily damaged region of the Lushan earthquake and continuously worked for over 20 days. 507 residential buildings were investigated thoroughly, concerning the type of building, construction time, retrofitting method, site situation, and damage pattern, and so on. This paper analyzed the seismic damage index, summarized the damage patterns of masonry residential buildings, and made comparisons between buildings located at different seismic intensity zones, and with different construction time. The weak points from structural point of view are indicated for the masonry residential buildings, and the seismic enhancement techniques and retrofitting methods are suggested accordingly.

Results:
Because of the insufficient constructional measures, irregularity of plan and elevation, too large aspect ratio, and deficient field conditions, the masonry residential building in Lushan area performed various damage patterns:
(1) Insufficient constructional measures are classified into two categories, i.e., horizontal insufficiency of constructional columns and vertical irregularity of constructional columns. Horizontal insufficiency caused link damage between transversal and longitudinal walls, pure shear damage in transversal walls, shear cracks in walls between windows, and even local compressive damage at positions sustaining concentrated loads. Vertical irregularity of constructional columns means the concrete column was broken at middle stories but not ended at the roof. The lack of confinement of top stories above the broken point commonly resulted in overall damage of top stories, and even overturning.
(2) Vertical irregularity of structures means the penthouses protruded over the roof, which are vulnerable to the ‘whip-tip’ effect during earthquake, particularly for those without constructional measures. It is suggested to be enhanced by four concrete columns at the four corners. The columns shall be connected to the confinement beams or constructional columns of lower stories. A cast-in-site concrete roof is preferred to enhance the integrity, while thinner masonry walls than 180mm shall be avoided.
(3) Some buildings on weak field conditions were damaged because of the failure of foundations.

Conclusions:
Learned from Wenchuan earthquake, the seismic measures of local residential buildings have been promoted, and most buildings have been constructed as confined masonry structures. This is the major reason that the seismic damage is averagely smaller than that observed in Wenchuan earthquake. However, the position and distribution of the constructional columns are often changed arbitrarily according to the occupant’s request, resulting in insufficient confinement or vertical irregularity. This mitigates the confinement effect so that some buildings were damaged seriously. The other reason lies upon the site condition. Once built on a soft field, and if the field is not well treated, non-uniform settling occurs which is going to lead the damage of foundation beam and the superstructure consequently. Finally, it is suggested that further instruction on the seismic safety measures, aseismic technology, ground treatment, and effective, economic, and rapid seismic retrofitting methods shall be studied and advanced in the future.

Objectives
Objectives:The Ms7.0strong earthquake hit Lushan county, Sichuan province, on April 20th, 2013, which caused significant human casualties and economic loss. Based on the field investigation, this paper systematically summarized the seismic damage patterns of masonry residential buildings, and evaluated the seismic fortification level of local masonry residential buildings after Wenchuan earthquake.
Methods
Methods:The data of this paper is collected by means of field investigation. The authors immediately entered the heavily damaged region of the Lushan earthquake and continuously worked for over 20 days. 507 residential buildings were investigated thoroughly, concerning the type of building, construction time, retrofitting method, site situation, and damage pattern, and so on. This paper analyzed the seismic damage index, summarized the damage patterns of masonry residential buildings, and made comparisons between buildings located at different seismic intensity zones, and with different construction time. The weak points from structural point of view are indicated for the masonry residential buildings, and the seismic enhancement techniques and retrofitting methods are suggested accordingly.
Results
Results:Because of the insufficient constructional measures, irregularity of plan and elevation, too large aspect ratio, and deficient field conditions, the masonry residential building in Lushan area performed various damage patterns:(1) Insufficient constructional measures are classified into two categories, i.e., horizontal insufficiency of constructional columns and vertical irregularity of constructional columns. Horizontal insufficiency caused link damage between transversal and longitudinal walls, pure shear damage in transversal walls, shear cracks in walls between windows, and even local compressive damage at positions sustaining concentrated loads. Vertical irregularity of constructional columns means the concrete column was broken at middle stories but not ended at the roof. The lack of confinement of top stories above the broken point commonly resulted in overall damage of top stories, and even overturning.(2) Vertical irregularity of structures means the penthouses protruded over the roof, which are vulnerable to the ‘whip-tip’ effect during earthquake, particularly for those without constructional measures. It is suggested to be enhanced by four concrete columns at the four corners. The columns shall be connected to the confinement beams or constructional columns of lower stories. A cast-in-site concrete roof is preferred to enhance the integrity, while thinner masonry walls than 180mm shall be avoided.(3) Some buildings on weak field conditions were damaged because of the failure of foundations.
Conclusion
Conclusions:Learned from Wenchuan earthquake, the seismic measures of local residential buildings have been promoted, and most buildings have been constructed as confined masonry structures. This is the major reason that the seismic damage is averagely smaller than that observed in Wenchuan earthquake. However, the position and distribution of the constructional columns are often changed arbitrarily according to the occupant’s request, resulting in insufficient confinement or vertical irregularity. This mitigates the confinement effect so that some buildings were damaged seriously. The other reason lies upon the site condition. Once built on a soft field, and if the field is not well treated, non-uniform settling occurs which is going to lead the damage of foundation beam and the superstructure consequently. Finally, it is suggested that further instruction on the seismic safety measures, aseismic technology, ground treatment, and effective, economic, and rapid seismic retrofitting methods shall be studied and advanced in the future.
Keywords
lushan earthquake; masonry residential buildings; seismic damage investigaground treatmenttion; seismic measures
王涛_图1 (a) 无构造措施砖混结构Masonry residential buildings without constructional measures
王涛_图1 (b) 无构造措施砖混结构Masonry residential buildings without constructional measures
图1 (a) 无构造措施砖混结构
图1 (b) 无构造措施砖混结构
王涛_图2 (a) 平面内构造柱设置不足Insufficient confinement of the constructional columns in plane
王涛_图2 (b)平面内构造柱设置不足 Insufficient confinement of the constructional columns in plane
图2 (a) 平面内构造柱设置不足
图2 (b)平面内构造柱设置不足
王涛_图3 (a)龙门乡(IX度区)某砖混结构A masonry residential building at Longmen
王涛_图3 (b)龙门乡(IX度区)某砖混结构A masonry residential building at Longmen
图3 (a)龙门乡(IX度区)某砖混结构
图3 (b)龙门乡(IX度区)某砖混结构
王涛_图3 (c)龙门乡(IX度区)某砖混结构 A masonry residential building at Longmen
王涛_图3 (d)龙门乡(IX度区)某砖混结构 A masonry residential building at Longmen
图3 (c)龙门乡(IX度区)某砖混结构
图3 (d)龙门乡(IX度区)某砖混结构
王涛_图4 (a)构造柱竖向分布不规则Vertical irregularity of constructional columns
王涛_图4 (b)构造柱竖向分布不规则Vertical irregularity of constructional columns
图4 (a)构造柱竖向分布不规则
图4 (b)构造柱竖向分布不规则
王涛_图5 (a)出屋面部分的破坏 Seismic damage of penthouses
王涛_图5 (b)出屋面部分的破坏 Seismic damage of penthouses
图5 (a)出屋面部分的破坏
图5 (b)出屋面部分的破坏
王涛_图6 (a)不同厚度墙体的破坏 Seismic damage of masonry walls with different thickness
王涛_图6(b) 不同厚度墙体的破坏Seismic damage of masonry walls with different thickness
图6 (a)不同厚度墙体的破坏
图6(b) 不同厚度墙体的破坏
王涛_图7 (a)隆兴乡(IX度区)某民宅A masonry residential building at Longxing
王涛_图7 (b)隆兴乡(IX度区)某民宅A masonry residential building at Longxing
图7 (a)隆兴乡(IX度区)某民宅
图7 (b)隆兴乡(IX度区)某民宅
王涛_图8 (a) 隆兴乡(IX度区)某三层民宅地基沉降Non-uniform settling of foundation
王涛_图8 (b)隆兴乡(IX度区)某三层民宅地基沉降Non-uniform settling of foundation
图8 (a) 隆兴乡(IX度区)某三层民宅地基沉降
图8 (b)隆兴乡(IX度区)某三层民宅地基沉降
王涛_图9(a) IX度区几乎完好的砖混民居Almost perfect masonry residential buildings in IX region
王涛_图9 (b) IX度区几乎完好的砖混民居 Almost perfect masonry residential buildings in IX region
图9(a) IX度区几乎完好的砖混民居
图9 (b) IX度区几乎完好的砖混民居
王涛_图9 (c) IX度区几乎完好的砖混民居Almost perfect masonry residential buildings in IX region
王涛_图10 (a) 典型民居构造 Typical configuration of masonry residential buildings
图9 (c) IX度区几乎完好的砖混民居
图10 (a) 典型民居构造
王涛_图10 (b) 典型民居构造 Typical configuration of masonry residential buildings
王涛_图11(a) IX区民居建筑破坏 Seismic damage of masonry residential buildings in IX region
图10 (b) 典型民居构造
图11(a) IX区民居建筑破坏
王涛_图11 (b) IX区民居建筑破坏Seismic damage of masonry residential buildings in IX region
王涛_图11 (c) IX区民居建筑破坏 Seismic damage of masonry residential buildings in IX region
图11 (b) IX区民居建筑破坏
图11 (c) IX区民居建筑破坏
王涛_图12 (a) VIII区民居建筑破坏Seismic damage of masonry residential buildings in VIII region
王涛_图12 (b) VIII区民居建筑破坏Seismic damage of masonry residential buildings in VIII region
图12 (a) VIII区民居建筑破坏
图12 (b) VIII区民居建筑破坏
王涛_图12 (c) VIII区民居建筑破坏Seismic damage of masonry residential buildings in VIII region
王涛_图12 (d) VIII区民居建筑破坏Seismic damage of masonry residential buildings in VIII region
图12 (c) VIII区民居建筑破坏
图12 (d) VIII区民居建筑破坏
王涛_图12 (e) VIII区民居建筑破坏Seismic damage of masonry residential buildings in VIII region
王涛_图13 (a)无约束砌体与约束砌体结构的抗震性能Seismic performance of unconfined and confined residential buildings
图12 (e) VIII区民居建筑破坏
图13 (a)无约束砌体与约束砌体结构的抗震性能
王涛_图13 (b) 无约束砌体与约束砌体结构的抗震性能Seismic performance of unconfined and confined residential buildings
王涛_图14 (a) 现浇楼板和预制楼板的抗震表现Seismic performance of cast-in-site RC slab and prefabricated RC slab
图13 (b) 无约束砌体与约束砌体结构的抗震性能
图14 (a) 现浇楼板和预制楼板的抗震表现
王涛_图14 (b) 现浇楼板和预制楼板的抗震表现Seismic performance of cast-in-site RC slab and prefabricated RC slab
王涛_图15 (a)圈梁挑梁的设置Configuration of ring beam and cantilever beam
图14 (b) 现浇楼板和预制楼板的抗震表现
图15 (a)圈梁挑梁的设置
王涛_图15 (b) 圈梁挑梁的设置Configuration of ring beam and cantilever beam
王涛_表1 高烈度区主要民居类型的破坏比和平均震害指数Damage ratio and mean damage index of typical residential structures in high-intensity regions
图15 (b) 圈梁挑梁的设置
表1 高烈度区主要民居类型的破坏比和平均震害指数
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