Chapter 7 7.1 Introduction 7.er Wenchua Earthquake Seismic Design of Masonry Buildings 7.5 Details 7.Intrednction Multi-sory mo ry bu multi-story buildings with inner frames 7.1 Introduction 7.1.I Multi-story masonry buildings
Chapter 7 Seismic Design of Masonry Buildings Chapter 7: Seismic Design of Masonry Buildings 7.1 Introduction 7.2 Considerations after Wenchuan Earthquake 7.3 Design criteria 7.4 Essentials in calculation of masonry buildings 7.5 Details 7.1 Introduction n Multi-story masonry structures are still the major type in the vast areas of China and other developing countries n Masonry structures in china mainly include u multi-story masonry buildings u multi-story buildings with framed first one/two stories u multi-story buildings with inner frames u Multi-story masonry buildings Vertical bearing elements: Masonry walls; Floors and Roof: reinforcing-concrete in site, prefabricated pre-stressed concrete slabs, timber joist and panels Steel truss or timber truss ? 7.1 Introduction 7.1.1 Multi-story masonry buildings 7.1 Introduction 7.1.1 Multi-story masonry buildings
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7.1 Introduction : Multi-story masonry buildings 7.1 Introduction : Multi-story masonry buildings u Multi-story masonry buildings with framed first one/two stories Masonry structure are used for the upper stories, and reinforced concrete frame with masonry walls are applied in the lower first one/two stories. 7.1 Introduction : 7.1.2 Multi-story masonry buildings with framed first one/two stories （with dual system） 7.1 Introduction : 7.1.2 Multi-story buildings with framed first one/two stories 7.1 Introduction : Multi-story buildings with framed first one/two stories
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u Multi-story masonry buildings with inner frames Masonry walls and columns are adopted in exterior bearing walls and multi-row columns are employed for interior bearing system. 7.1 Introduction : multi-story masonry buildings with inner frames u Multi-story buildings with inner frames Masonry walls and columns are adopted in exterior bearing walls and multirow columns are employed for interior bearing system. 7.1 Introduction : 7.1.3 Multi-story buildings with inner frames n 7.1 Introduction : 7.1.4 Special Masonry buildings —— Church 7.1 Introduction : Old Church
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7.1 Introduction 7.1.4 modern masonry （with dual material） n Ductile design n to have masonry structures in high seismic areas designed capable of considerable inelastic behavior without a failure. n Confined masonry and/or reinforced masonry n consist of reinforced-concrete or reinforced-masonry elements such as constructional columns, core columns and ring beams etc., which confine the masonry walls along the edges n steel reinforcement n placed either in the joints and pockets between the units and embedded in the mortar, or in especially provided holes and channels within the units and grouted with concrete or grout n reinforced hollow unit masonry n horizontal reinforcement placed in the bed joints carries the shear n vertical reinforcement subjected lateral loads n truss mechanism in the wall, the tension components of bending and shear forces due to lateral load are carried by steel, and the compression components are carried by the masonry units 7.1 Introduction 7.1.4 modern masonry n Building’s Collapse n Diagonal Crakes of masonry walls n Failure of connection with walls n Floor collapse n Damages of Building’s corners n Damages of staircase rooms n Damages of Non-structural elements 7.2 Considerations after Wenchuan Earthquake Building’s Collapse Building’s Collapse Diagonal Crakes of masonry walls
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Diagonal Crakes of masonry walls Diagonal Crakes of masonry walls Diagonal Crakes of masonry walls Diagonal Crakes of masonry walls Floor collapses For Comparison
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For Comparison Concrete panels fall down Corner damaged 二十二、设备管线削弱墙体 Weakened masonry wall caused by the plant pipe Damage of th二十三 e curve、d弧形maso墙nr震害y wall 二十五、拦板震害 Damage of parapets
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唐山地震 (Tangshan，China，1976） 7.3 Design criteria 7.3.1 Configuration of plan and elevation 7.3.2 Configuration of structural system of multi-story masonry buildings 7.3.3 Configuration of structural system of multi-story masonry buildings with framed first one/two stories 7.3.4 Configuration of structural system of multi-story masonry buildings with multi-row columns of inner frame 7.3.1 Configuration of plan and elevation 1. In general, the configuration of plan and elevation of buildings should be regular and symmetric. 2. Distribution of mass and change in stiffness should be even. 3. The floors of the buildings should not be staggered. 7.3.1 Configuration of structural system of multi-story masonry buildings 1. Priority shall be given to the use of structural systems with transverse bearing walls or both transverse and longitudinal bearing walls. 2. Distribution of longitudinal and transverse walls should be uniform and symmetrical, aligned in-plane, and shall be continued in elevation. The walls between the windows on the same axis should be distributed uniformly 7.3.1 Configuration of structural system of multi-story masonry buildings 3. In the intensity of Ⅷ and Ⅸ and in one of the following cases as well, a seismic joint (防震缝) should be installed. Walls shall be installed on both sides of the joint and the joint gap (防震缝宽度) can be taken as 70 to 100mm. n Difference in heights on the elevation of buildings exceeds 6m; n In buildings with staggered stories and with relatively large difference between floor levels in elevation; n Stiffness and mass of different parts of the structure are sharply different
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7.3.1 Configuration of structural system of multi-story masonry buildings 4. Staircase should not be installed at the end or in the corner of a building. 5. The installation of flues(烟道), ventilation ducts（管道）, and garbage ducts in a building shall not weaken the wall. When the wall is weakened, strengthening measures shall be taken. Flues adhered to the wall without vertical reinforcement or chimneys on the roof should not be used. 6. Precast reinforced concrete eaves(屋檐) without anchorage should not be used. 7.3.2 multi-story masonry buildings with framed first one/two stories n The masonry shear wall in upper part should be aligned with the beams of frame or shear wall in the lower framed part. n In the lower framed stories, certain members of shear walls shall be arranged symmetrically along the longitudinal and the transversal direction, and shear walls should be uniform and symmetrical basically. n For the masonry buildings with framed first one stories, the ratio of lateral drift stiffness of the second story to that of the first story shall be not greater than 2.5 and 2 in the intensity of Ⅶ and Ⅷ respectively. n For the masonry buildings with framed first two stories, the ratio of lateral drift stiffness of the third story to that of the second story shall be not greater than 2.0 and 1.5 in the intensity of Ⅶ and Ⅷ respectively. And the stiffness of the first one should be near to that of the second story. n There should be the raft footing, pile foundation or strip foundation for shear walls of the masonry buildings with lower framed stories. 7.3.2 multi-story masonry buildings with framed first one/two stories 7.3.4 multi-story masonry buildings (GB50011-2010) with inner frames n The buildings should be rectangular in plane and regular in elevation. n The spacing of the transverse walls should not greater than 15m and 11m in the intensity of Ⅶ and Ⅷ respectively. n There should be the raft footing, pile foundation or strip foundation for shear walls of the masonry buildings with multi-row columns of inner frame