Resistance of structures

The dynamic methods used are a modal analysis with a spectrum as an input and a space-time history analysis which needs one or more accelerograms for inputs. Analyses of the first type are the most common ones the second type is used in particular cases or for the accurate study of the response of a plant component placed at a specific place in a structure. 

The seismic engineering texts (e.g. CasteUani el al., 2000) and the many electronic computer programs now available (SAP, MARC, ADYNA, ANSYS, etc.) are a reliable basis for these analyses, but considerable computer-power may be needed, with associated high costs, where a plastic analysis of complex structures has to be performed. Similarly, the inclusion of ductility factors, where allowed and made in a conservative way, has to be done with care and attention in particular it is necessary to distinguish between ductility of a structure point (section) and the complex of the structure, to avoid an excessively conservative outcome and to highlight the possible onset of self-amplification of the cycle load-deformation phenomena P- effects), already mentioned above. 

The following section details some elements of dynamic analysis which are useful for indicative evaluations. 

The overall characteristics which make a structure particularly resistant to an earthquake are its symmetry in the distribution of masses and rigidities, its compactness, possibly its low height, the good connection between horizontal and vertical elements, the connection between isolated foundation elements, the uniformity and competency of the foundation soil, the provisions against impact between adjacent structures, and the absence of negative effects of non-structural elements (filling walls, etc.) (CasteUani et al., 2000 Livolant et al., 1979). 

The absence of P- effects (i.e. the strong increase of the loading characteristics, e.g. moments, because of the deformation of the structure) is also to be considered. 

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Table 4.93 Corrosion resistance of structural ceramics to fused salts, alkalis and low-melting oxides...

The corrosion resistance of structural ceramics consisting of oxides and non-oxides is presented in Table 4.93. The data presented in the table are of limited generality. The code letters A, B and C must be used for comparison of the materials. It is obvious from the data that both oxide-based and non-oxide-based ceramic materials are attacked at low and intermediate temperatures. The relatively poor corrosion resistance of SiC and Si3N4 may be due to the formation of Si02 layers on the ceramic components. More detailed information on the corrosion resistance of structural ceramic materials may be found in the literature.111... 

In this paper, the importance of particle and whisker reinforcement to creep and creep rupture behavior of ceramics is discussed. Particle and whisker additions generally increase both the fracture toughness and creep resistance of structural ceramics. These additions also act as nucleation sites for cavities. Cavities form preferentially in tensile specimens. This results in a creep asymmetry, in which composites creep faster in tension than in compression. As a consequence of cavitation, the stress exponent for creep in tension 6-10,... 

Corrosion resistance of structural iron-base alloys in high-temperature environments is typically achieved by formation of a continuous... 

The resistance of structures was measured by a four-contact method simultaneously parallel and perpendicularly to the step edges of vicinal surface in the temperature interval 4.2-300 K. The Hall effect and magnetoresistance were investigated in magnetic fields up to 0.5 T. 

A careful control of the purity of the coolant is required to avoid the formation of such deposits. It was necessary to develop corrosion resistant steels and to pre-treat the surfaces of components and also to use special inhibitors in the lead-bismuth coolant. More extensive studies are required for lead coolant to demonstrate the corrosion-resistance of structural material. 

The principle solutions ensuring high corrosion resistance of structural materials in heavy liquid metal coolant were found using oxygen dissolved in the coolant. It has been shown as a result of long-term studies that this corrosion resistance essentially depends on concentration of dissolved oxygen. 

The problem of hyperthermal corrosion resistance of structural materials was got over by development of preliminary protective coatings for the working steel surfaces. In particular, the most important structural units of circuit, e.g. fuel rod claddings and steam generator tubes, are covered by these coatings at the final stage of their manufacture. Additional barriers are also formed directly on the inner surfaces of liquid metal circuit under effect of the coolant in the early stage of the reactor operation. 

ROUSSANOV, A., et. al.. Corrosion resistance of structure materials in lead coolant with reference to reactor installation paper presented at the International Seminar on Cost, Competitive, Proliferation Resistant Inherently and Ecologically Safe Fast Reactor and Fuel Cycle for Large Scale Power , MINATOM, Moscow, 29 May-1 June, (2000),pp. 65-67. 

In the USA the scientific and research development works were conducted on using lead-bismuth coolant (LBC), but the alternative to solving the problem of corrosion resistance of structure materials and maintenance of coolant quality (the coolant technology) did not give any positive results and those works were stopped. 

FATIGUE CRACK GROWTH RESISTANCE OF STRUCTURAL ALLOYS AT CRYOGENIC TEMPERATURES... 

Fatigue Crack Growth Resistance of Structural Alloys at Cryogenic Temperatures... 

R. L. Tobler and R. P. Reed, Fatigue Crack Growth Resistance of Structural Alloys at Cryogenic Temperatures, Report NBSIR 76-848, National Bureau of Standards, Boulder, Colorado (1976). 

A torsional impact test, developed by the GMC Technical Center, Warren, Mich., was used to compare the relative toughness and impact resistance of structural adhesives. In this test, a 3.6-lb. weight falls in a 20-inch, 90 -arc to impact a one-half inch overlap bonded lap shear positioned at a right angle to the bond. The impact scale reads directly in inch-pounds of force needed to break the bond. Sixty inch-pounds is the limit of the test. Steel and aluminum lap shears severely deform near this limit. Table 4 illustrates the typical values obtained. 

FIGURE 14.25. Corrosion resistance of structural materials to chlorine [27). 

Fabrication technologies to ensure high corrosion and radiation resistance of structural materials ... 

The problems of lead technology, corrosion resistance of structural materials and mass transfer in the primary circuit were comprehensively addressed and resolved when operating second generation reactor installations, there were no problems with corrosion resistance of structural materials or in meeting the requirements for coolant and circuit quality [XIX-2] ... 

This chapter provides a summary of the generalized theory and a discussion of the parameters which appear in its equations. The use of the theory is illustrated for several different adhesion situations, including the peeling of rubberlike and pressure-sensitive adhesives, adhesion to skin, and the moisture resistance of structural adhesives bonded to metals and glass. 

EN 1998-4 (2006) Eurocode 8 Design Provisions for Earthquake Resistance of Structures —Part 4 Silos, Tanks and Pipelines. CEN, Brussels. 

Note Stress ratio A = 0.1, at 20 to 28 Hz compact specimens, (a) NI - normal interstitial, LI = low interstitial, ELI = extra low interstitial. Source R. L. Ibbler and R.P. Reed, Fatigue Crack (Srowth Resistance of Structural Alloys at Cryogenic Temperatures, in Advances in Cryogenic Engineering, KD. Timmerhaus et al., EkL, Vol 24, Plenum Press, 1978, p 82-90... 

J.A. Milke, Analytical methods to evaluate fire resistance of structural members. Journal of Structural Engineering ASCE (American Society of Civil Engineers), 125(10), pp. 1179-1187, 1999. 

A.206. In this section the design criteria for the resistance of structures, systems and components to external events should be presented. These may include ... 

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