Tài liệu SEISMIC DESIGN FOR ARCHITECTS OUTWITTING THE QUAKE ppt

[...]... deforming the rock After rupture the land rebounds Fault movement ▲ 1.3 Increase of strain adjacent to a fault plane and the subsequent energy release and fault displacement a sideways force at the interface between the surfaces (Fig 1.4(b)) If the initial pressure is low, they slide past each other without snapping Increasing the pressure and the sideways force distorts the flesh When the sliding force... how they differ from other forces such as those caused by the wind, that also act upon buildings The following sections then explore the key physical properties that affect the severity of seismic forces After appreciating those factors that influence levels of seismic force, the basic requirements for seismic resistance are considered This in turn leads to an introduction to building torsion and the. .. AFFECTING THE SEVERITY OF SEISMIC FORCES Building weight The single most important factor determining the inertia force in a building is its weight Newton’s Law states that inertia force is proportional to mass or weight The heavier an object the greater the inertia force for a certain level of acceleration In earthquake prone regions, we should therefore build as light-weight as practicable to reduce seismic. .. vibration (a) and the first mode of vibration as the source of most inertia force (b) When earthquake waves with their chaotic period content strike the foundations of a building, its superstructure responds to the various periods of vibration that are all mixed-up together to comprise the shaking The different periods of vibration embedded within the earthquake record 20 SEISMIC DESIGN FOR ARCHITECTS cause... method for calculating the natural period of vibration is to multiply the number of storeys of a building by 0.1 The natural period of a ten-storey building is therefore approximately 1.0 second The weight of the building The heavier a building, the longer the natural period, and finally, The type of structural system provided to resist seismic forces The more flexible or less stiff a structure, the longer... further As the sum of gravity forces acting on an element can be assumed to act at its centre of mass (CoM), so can the inertia force on any item be considered to act at the same point Since most of the weight in buildings is concentrated in their roofs and floors, for the sake of simplicity designers assume inertia forces act at the CoM of the roof and each floor level (Fig 2.3) For most buildings the CoM... adequate seismic resistance 4 SEISMIC DESIGN FOR ARCHITECTS U NDERSTANDING EARTHQUAKES This section explains why architects might need to design earthquakeresistant buildings It introduces the basic geological mechanisms causing earthquakes, explaining where and when earthquakes occur and the characteristics of ground shaking relevant to buildings The focus here is upon those aspects of earthquakes... earthquakes to subterranean beings holding up the world Whether in the form of fish, animals or people, when they changed position to relieve their unrelenting burden, the earth shook Many cultures possessed or still possess their own god or gods of earthquakes Peoples like the Central Asian Turks valued jade as a talisman credited with the power to protect them from, among other dangers, earthquakes... classroom The children stood up As they began their morning greeting of ‘Good morning, Sir’ the earthquake hit The teacher stepped back in surprise, the roof collapsed They all died, all 50 of them, just like that No wobbling walls and dashes for the door No warning One second you have a classroom full of children in front of you, and the next, they are dead’.2 If the potential source of an earthquake... which we as designers have no control Having outlined in this chapter what might be termed the earthquake problem, the remaining chapters deal with the solutions For more detailed yet not too highly technical information on the basics of earthquake occurrence, the reader can refer to one of several general introductory texts.5 Why earthquakes occur Compared to the 6400 km radius of the earth, the thickness . alt="" SEISMIC DESIGN FOR ARCHITECTS OU TW ITTING THE QUAKE This page intentionally left blank SEISMIC DESIGN FOR A RCHITECTS OUTWITTING THE QUAKE . earthquakes 15 Introduction 15 Nature of seismic forces 15 Factors affecting the severity of seismic forces 18 Resisting seismic forces 25 Torsion 27 Force