Bfv

Where E is Young's modulus and v is Poisson's ratio. In the absence of any more specific data, low strain values of E may be taken from Table 5.3. Values of Poisson's ratio from Table 5.4 may be used in the above formula. Table 5.3 Typical modulus of elasticity values for soils and rocks Table 5.3 Typical modulus of elasticity values for soils and rocks

837 Choice of construction materials

Reliability of construction in earthquakes is greatly affected by the materials used for the constituent elements of structure, architecture, and equipment. It is seldom possible to use the ideal materials for all elements, as the choice may be dictated by local availability of local construction skills, cost constraints, or political decisions. Purely in terms of earthquake resistance the best materials have the following properties (2) high strength weight ratio (5) ease in making full...

443Degree of fault activity

Active faults include any faults which are considered capable of rupturing in the future. Because the amount and frequency of movement can vary enormously, it is important Figure 4.3 The main fault types to be considered in the study of strong ground motion (adapted from Housner, 1973) Figure 4.3 The main fault types to be considered in the study of strong ground motion (adapted from Housner, 1973) to be able to estimate the degree of activity likely to be exhibited by any fault in the region...

1

Figure 8.17 South Rangitikei railway bridge, New Zealand, showing locations of bearings and torsion beam energy dissipators (Skinner et al.y 1980) under the control of hysteretic dampers of the tapered steel cantilever type, similar to those used for the Union House building discussed in Section 8.5.4. 8.5.6 Energy dissipators for seismically-isolated structures In the preceding sections on isolation methods, we have discussed a number of energy dissipators (dampers) that have been used with...

135 Retrofitting Structures

The retrofitting of a structure involves improving its performance in earthquakes through one or more of Increasing its strength and or stiffness. Reducing the input seismic loads. This may be done through modifications to one or more of Joints between structural elements. By way of example, three ways of improving the performance of weak or brittle columns suggested by Park (2001) are illustrated in Figure 13.3. These comprise (a) Adding reinforced concrete jackets, either as a full surround,...

Dd

Butt weld top and btm plates 1 s filler plate 31 2 x 3 x 3 s Z welded to column (2) A fillet-welded joint using flange plates. (3) A joint using high-strength bolts and flanges plates. In the tests it was found that the butt-welded joints were superior to the other two types in terms of total energy absorption. In the bolted joints, the hysteresis loops were reduced in area considerably by slippage, although the use of smaller than normal oversize holes reduced this effect. All the joints...

Info

Gap filled with flexible sealant (section 8.2.3.) Figure 12.7 Detail of external frame showing separation of spandrel from columns to avoid unwanted interaction Precast concrete cladding is discussed in Section 10.3.12. Suffice it here to point out that in flexible buildings, non-structural precast concrete cladding should be mounted on specially designed fixings which ensure that it is fully separated from horizontal drift movements of the structure. Brick or other rigid cladding should be...

Yielding Of Steel In Singly Reinforced Be Occurs In

Under Reinforced Section

Required ductility (robustness) of concrete structures Referring again to objective (c) above, the degree to which ductility should be enhanced is debatable. Until the 1990s, research and codes had rightly been preoccupied with overcoming the excessive brittleness and unreliability of ill-reinforced concrete. However, there may have been too much emphasis of creating ductility for ductility's sake. The high cost of design and the complexity of some of the reinforcement of highly ductile...

002

Figure 6.18 (a) Mean damage ratio and its 95 confidence limits for single storey weatherboard houses, excluding chimney damage, at intensity MM8.5 (Westport, New Zealand) for two types of foundation and two ground classes, in the 1968 Inan-gahua earthquake (b) mean damage ratio and its 95 confidence limits for single storey weatherboard houses, including chimney damage, at intensity MM8.5 (Westport) for two types of foundation and two ground classes, in the 1968 Inan-gahua earthquake (from...

22 Global Seismotectonics

On a global scale, the present-day seismicity pattern of the world is illustrated in general terms by the seismic events plotted in Figure 2.1. Most of these events can be seen to follow clearly defined belts which form a map of the boundaries of segments of the earth's crust known as tectonic plates. This may be seen by comparing Figure 2.1 with Figure 2.2, which is a world map of the main tectonic plates taken from the highly understandable book on the theory of continental drift by Stevens...

J

Two straps each corner nailed to sheathing with two nails per board a. Effect of sheathing on frame walls having no openings. A and B, 1 x 8 in. lumber C, 25 32 in. fibertoard D and E, 5 8 in. plywood F, G, and H, 1 4 in. thick plywood. b. Effect of sheathing on frame walls with window and door openings. A, B, C, and D, 1 x 8 in. lumber E and F, 25 32 in. thick fiberboard G. & H. 1 4 in. thick plywood. c. Influence of bracing on rigidity and strength of frame walls sheathed with 1 x 8 in....

S

Figure 4.40 Set of simulated input accelerograms and response spectra for a magnitude 7.0 earthquake with a closest distance to the causative fault of 50 km (after Valera and Donovan, 1973) distant events because of the greater long-period content of such events, while short-period structures designed to the same hazard level may be more sensitive to smaller, closer events. To further illustrate the point, Kuala Lumpur in Malaysia is located at the rather remote distance of about 400 km from...

343 Laboratory tests relating to dynamic behaviour of soils

A brief description of the nature, applications and limitations of the laboratory tests relating to the dynamic behaviour of soils, as summarized in Tables 3.2 and 3.3 is set out below. This soil property is related to the liquefaction of saturated cohesionless soils as discussed in Section 5.2.2. As the test for its determination is a standard laboratory procedure, it will not be described here. Although a number of classifications of grain size and standard sieves exist, correlations are...

Enlarged Connection Detail

Continuity bars welded to M.S. plate Continuity bars welded to M.S. plate Detail 10.16 Site welding and mortaring. Lapping steel plate bent on site to suit differential camber of adjacent precast units Connections adjacent precast wall units The following typical details (Details 10.17-10.22) should be designed for the forces acting on the joint under consideration. Great problems occur in producing a ductile and easily-erected precast shear wall, and no universal solution has as yet been...

05

Figure 8.14 Section through the William Clayton Building, Wellington, New Zealand, the first building to be seismically isolated. The lead-rubber bearings are shown beneath the basement (after Megget, 1978) Figure 8.15 Section through Union House, Auckland, New Zealand, showing isolating piles and energy dissipators (after Boardman et al., 1983) Figure 8.15 Section through Union House, Auckland, New Zealand, showing isolating piles and energy dissipators (after Boardman et al., 1983)...

853 Seismic isolation using flexible bearings

The most commonly used method of introducing the added flexibility for seismic isolation is to seat the item concerned on either rubber or sliding bearings. The energy dissipators (dampers) that must be provided may come in various forms. For use with standard bridge-type bearings made of rubber or sliding plates, any of the energy dissipators mentioned in Section 8.5.6 may be suitable. In addition, all-in-one devices, incorporating both isolation and damping, are used, namely lead-rubber and...

Hmo

Detail 10.20 Site welded and concreted full separation difficult to achieve, and some interaction of frame and cladding through bending of the connections may have to be accepted. Ductile behaviour of the cladding and of its connections to the structure is most important in such cases, to ensure that the cladding does not fall from the building during an earthquake. In stiff (shear wall) buildings the storey drift will generally be small enough to significantly reduce the problem of detailing...

2

Connections in diagonally braced frames In addition to the above principles, special considerations relating to failure mode control arise in the design of connection in diagonally braced frames, as discussed elsewhere (Sidwell, 1985 Walpole, 1985b HERA, 1999). In many steel structures, particularly multi-storey buildings, the steel acts compositely with concrete which is used for floors or fire protection of columns. Obviously, the Figure 10.17 Forces acting on a typical panel zone Figure...

References

Aguilar J, Juares H, Ortega R and Iglesisas J (1989) Statistics of retrofitting techniques in reinforced concrete buildings. Earthquake Spectra 5(1) 145-52. Applied Technology Council (1996) ATC 40 The Seismic Evaluation and Retrofit of Concrete Buildings. 2 volumes. Redwood City, USA. Bell DK and Davidson BJ (2001) Evaluation of earthquake risk buildings with masonry infill panels. Paper No 4.02.01. Technical Conference of NZ Soc for Earthq Eng, Wairakei, New Zealand. Bertero VV, Anderson JC...

D

The position of the yield moment (and the length of pile shaft over which soil failure occurs) is given by where e0 and fs define the simplified lateral stress regime adopted for the top of the pile (Figure 9.4). For a fixed head pile the ultimate lateral capacity will be given by The above four equations are based on the same assumptions as Broms, with the exception that e0 is 0.6m for Budhu and Davies and 1.5D for Broms. The minimum length of pile shaft required for this solution to be valid...

Vfy Cladding

Figure 10.41 Schematic illustration of supports for precast concrete cladding fully separate from frame action Official recommendations for seismic design of prestressed concrete Some organizations interested in the use of prestressed concrete have published seismic design recommendations. For example, the FIP (1977) in addition to the New Zealand concrete code (NZS 3101, 1995), gives guidance on this subject. In contrast, the major USA concrete codes only discuss prestressed concrete in...

832 Simplicity and symmetry

Earthquakes repeatedly demonstrate that the simplest structures have the greatest chance of survival. There are three main reasons for this. First, our ability to understand the overall behaviour of a simple structure is markedly greater than it is for a complex one, e.g. torsional effects are particularly hard to predict on an irregular structure. Secondly, our ability to understand simple structural details is considerably greater than it is for complicated ones. Thirdly, simple structures...

1043 Reliable seismic behaviour of masonry structures

For obtaining reliable seismic response behaviour, the principles concerning choice of form, materials and failure mode control discussed in Section 8.3 apply to masonry structures, while further factors specific to masonry are discussed below. The wide range of masonry products, of clay and concrete types, means a wide range of material behaviour and hence of seismic reliability. Probably the most reliable type is reinforced hollow concrete blocks, which have been more studied than other...

I

Figure 6.9 Vulnerability measures for domestic property from the Inangahua earthquake compared with those from other earthquakes (a) Drm for houses, (b) Drm for contents, (c) Percentage of houses damaged, and (d) Percentage of contents parcels damaged (from Dowrick et al 2001) Figure 6.10 Plot of damage ratios for buildings versus contents for the MM9 zone of the 1987 Edgecumbe, New Zealand earthquake showing zero correlation, although Dr (buildings) Dr (contents) (from Dowrick, 1991)...

Cc

Figure 10.15 Beam-column connections with major axis column bending tested by Popov and Pinkney (1969). (a) Butt-welded beam-column joint (b) fillet welded beam-column joint (c) bolted beam-column joint Figure 10.15 Beam-column connections with major axis column bending tested by Popov and Pinkney (1969). (a) Butt-welded beam-column joint (b) fillet welded beam-column joint (c) bolted beam-column joint

12hd20

Figure 10.35 Elevation of a column in a ductile moment-resisting frame, showing splice located out of plastic hinge zone at column base reinforcement in the form of links should be added, especially where high shears exist, to help to confine the concrete in the development length. It is especially desirable to avoid anchorage bars in the 'panel' zone of beam-column connections. Large amounts of the reinforcement should not be curtailed at any one section. The minimum bend radius depends upon...

33 Ground Classes and Microzones

As soil types and thicknesses, and to a lesser extent rock, vary widely from site to site in a region and worldwide, many different ways of classifying sites exist. Fortunately as knowledge has grown in recent years of site response to earthquakes, there has been Total number of records analysed 104 Total number of records analysed 104

105

(1) Unclad refers to open industrial frameworks (perhaps with web grating steel flooring or platforms). Clad refers to most other structures such as offices. (1) Unclad refers to open industrial frameworks (perhaps with web grating steel flooring or platforms). Clad refers to most other structures such as offices. are conducted at low strain rates of about 10-3 s. Under seismic loading conditions in short period structures local strain rates may be in excess of 1.0 s, causing increases in fy of...

61 Introduction

To manage and minimize risk in future earthquakes, by design, planning and retrofitting, we need to understand and evaluate the earthquake vulnerability of the built and natural environments. This is best done by developing models by studying damage in past earthquakes, and quantifying the data on damage to a much greater degree than that which is possible in earthquake reconnaissance reports, or that given in the excellent book by Steinbrugge (1982). Earthquake damage to the built environment...

06

Sway Bracing Civil Engineering

Where Fac is the maximum compressive stress as a function of the slenderness ratio, calculated on a permissible stress basis, and As is the sectional area of the member. Where uniaxial bending occurs about the major principal axis design bending moment M* should satisfy where the strength reduction factor, and Mrx the nominal section moment capacity, reduced by axial force (tension or compression), Msx(1 (N* Ns)), where N* is the design axial force, Ns is the nominal section capacity for axial...

836 Appropriate stiffness

In designing construction to have reliable seismic behaviour, the design of structures to have appropriate stiffness is an important task, often made difficult because so many criteria, often conflicting, may need to be satisfied. The criteria for the stiffness of a structure fall into three categories, i.e. the stiffness is required (1) To create desired vibrational characteristics of the structure (to reduce seismic response, or to suit equipment or function). (2) To control deformations (to...

51Introduction

This chapter is principally concerned with the determination of seismic motions, stresses, and deformations necessary for detailed design. The design earthquake (Chapter 4) is applied to the soil and or the proposed form and materials of the structure (Chapter 8). In earthquake conditions the relationship should ideally be analysed as a structural continuum. Although in practice this is seldom feasible, each of the parts should be seen as part of the whole when considering boundary conditions....

Dso

Figure 11.10 Belleville washer damper arrangement for the earthquake protection of equipment (from Pham and Hoby, 1991) At the other end of the size scale, for small items of equipment Belleville washers provide an inexpensive and simple means of damping seismic motions. As can be seen in Figure 11.10, these washers are conical spring washers, which are designed to achieve A shift in the natural period of the equipment they support to outside the range where the ground acceleration is...

1038Columns

The design notes given in this section are aimed primarily at columns which form part of ductile moment-resisting frames. Columns in other situations, such as (1) trapped spandrel columns in wall frame systems, (2) columns in flat slab structures, and require specific consideration, as outlined by Selna et al. (1980). Other general design requirements for columns are as follows (4) The minimum width of the compression face of a member should be 200 mm. (5) The minimum content of longitudinal...

48 Faults Hazard and Design Considerations 481 Introduction

Intuitively the thought of building across an active fault is alarming, and obviously in general it is best avoided. However, in some circumstances structures can safely ride a fault rupture. For example, in the 1972 Managua earthquake the Banco Central de Nicaragua was astride a fault which moved 17 cm (horizontally only), and its foundation was strong enough to deflect the rupture around itself and survive intact (Wyllie et al., 1977). Indeed the situation not infrequently arises when it is...

00004

Prestressed Concrete Earthquake

Where 00 004 is the curvature at a nominal maximum concrete strain of 0.004, and 0cr is the curvature at first cracking. The ductility or rotation capacity of prestressed concrete is affected by (1) The longitudinal steel content. (2) The transverse steel content. (3) The distribution of longitudinal steel. Each of these variables is discussed below. Longitudinal and transverse steel content From Figure 10.43, it may be seen that ductility decreases markedly with increasing prestressing steel...

845 Eccentrically braced frames

Traditional design of trussed structures lays great importance on keeping the forces in the structure to axial only, avoiding moments by ensuring that the centre-lines of all intersecting members meet at a point, i.e. concentrically (Section 8.4.4). However, starting in the late 1970s, the concept of using deliberately eccentric bracing for earthquake resistance purposes has been found to have certain advantages, so far principally for steel structures, with major structures being designed this...

854 Isolation using flexible piles and energy dissipators

An interesting alternative to the use of lead-rubber bearings is the isolation system used first for Union House (Boardman et al. 1983), a 12-storey office block in Auckland, New Zealand, completed in 1983 (Figure 8.15). As the building required end-bearing piles about 10 m long, the designers took the opportunity of making the piles flexible and separating them from lateral contact with the soft soil layer overlying bedrock by surrounding them with a hollow sleeve, thus creating the...

911 Introduction

As discussed in Chapter 5 the properties and dynamic behaviour of soils and their relationships to structures are complex and involve large uncertainties. In view of the challenges thus imposed on designers of foundations, Pender (1996) proposed three levels of design analysis for foundations, in a review of earthquake resistant design of foundations where design analysis was defined as all the calculation and analysis that is a central part of the design process. He described the three levels...

21 Introduction

An earthquake is a spasm of ground shaking caused by a sudden release of energy in the earth's lithosphere (i.e. the crust plus part of the upper mantle). This energy arises mainly from stresses built up during tectonic processes, which consist of interaction between the crust and the interior of the earth. In some parts of the world, earthquakes are associated with volcanic activity. For example, in Guatemala such earthquakes occur in swarms, with an average duration of three to four months,...

0036

(1) Predominantly cemented limestone. (1) Predominantly cemented limestone. The basis of the microzones was the geology of any deposits overlying bedrock, as mapped in the earlier microzoning study of Suggate and Wood (1979). Their map for Greymouth is reproduced here, slightly annotated, in Figure 6.14. Inangahua and Reefton, are entirely Ground Class C. The Ground Classes AB, C and D conform to the definitions used in the 2002 draft joint Australian New Zealand loadings standard. These...