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Canadian Journal of Civil Engineering (03151468)23(5)pp. 1051-1063
The Geological Survey of Canada is currently producing a suite of new hazard maps for Canada. These maps take into account the additional recorded data obtained during the past 13 years, as well as the new geological and tectonic information that has recently become available. They provide elastic spectral acceleration values for a uniform probability of exceedance of 10% in 50 years. A method of using the uniform hazard spectral values to obtain design response spectral curves for different values of ductility is presented here. The method uses two spectral values obtained from the hazard maps, the peak spectral acceleration for the site and the spectral acceleration corresponding to a period of 0.5 s. Empirical expressions are developed to represent the design response spectra. It is shown that by using inelastic spectral accelerations rather than the elastic spectral values in association with a reduction factor, the new method provides a more reliable estimate of the design forces.
Canadian Journal of Civil Engineering (03151468)25(1)pp. 1-15
Observations during many earthquakes have shown that building structures are able to sustain without damage earthquake forces considerably larger than those they were designed for. This is explained by the presence in such structures of significant reserve strength not accounted for in design. Relying on such overstrength, many seismic codes permit a reduction in design loads. The possible sources of reserve strength are outlined in this paper, and it is reasoned that a more rational basis for design would be to account for such sources in assessing the capacity rather than in reducing the design loads. As an exception, one possible source of reserve strength, the redistribution of internal forces, may be used in scaling down the design forces. This is because such scaling allows the determination of design forces through an elastic analysis rather than through a limit analysis. To assess the extent of reserve strength attributable to redistribution, steel building structures having moment-resisting frames or concentrically braced frames and from 2 to 30 storeys in height are analyzed for their response to lateral loading. A static nonlinear push-over analysis is used in which the gravity loads are held constant while the earthquake forces are gradually increased until a mechanism forms or the specified limit on interstorey drift is exceeded. It is noted that in moment-resisting frames the reserve strength reduces with an increase in the number of storeys as well as in the level of design earthquake forces. The P-Δ effect causes a further reduction. In structures having braced frames the main parameter controlling the reserve strength is the slenderness ratio of the bracing members. In these structures, reserve strength is almost independent of both the height of the structure and the effect of building sway.
Canadian Journal of Civil Engineering (03151468)27(3)pp. 563-580
The use of uniform hazard spectra for obtaining the seismic design forces is being considered for the next version of the National Building Code of Canada. Such spectra provide the spectral accelerations of a single-degree-of-freedom system for a range of periods but for a uniform level of hazard. One of the issues that need to be resolved before uniform hazard spectra are used in the design of multistorey buildings is the adjustment required in the base shear to account for the higher mode effects present in a multi-degree-of-freedom system. This issue is examined through analytical studies of the response of idealised elastic and inelastic multistorey building frames to ground motions representative of the seismic hazard in the eastern and western regions of Canada. Representative values are obtained for the adjustment factors that must be applied to the design base shear and to the base overturning moment.
Shock and Vibration Digest (17413184)32(1)pp. 67-67
The use of uniform hazard spectra for obtaining the seismic design forces is being considered for the next version of the national building code of Canada. Such spectra provide the spectral accelerations of a single-degree-of-freedom system for a range of periods but for a uniform level of hazard. One of the issues that needs to be resolved before uniform hazard spectra are used in design is the adjustment required in the base shear to account for the higher mode effects present in a multi-degree-of-freedom system. This issue is examined through analytical studies of the response of idealized multistorey building frames to ground motions representative of the seismic hazard in east and west Canada.
Institute of Physics Conference Series (09513248)180pp. 25-34
Geometry has a ritual origin and utilisation of Sacred Geometry by man goes back many centuries. Certain specific ratios can be found in the design of lifeforms in nature Traditional civilisations regarded architecture as a sacred means by which the heavens were manifested. Persian architecture utilised proportions comprehensively and by means of Sacred Geometry measured the proportions of heaven and reflected them in the dimensions of buildings on Earth. In this paper, the design of a number of Persian historical buildings by the use of the science of geometry will be presented. The geometric factors upon which the design of these buildings is made, from both architectural and structural viewpoints, will be discussed and common design laws between Persian monuments and creatures in nature will be explained.
Advances in Earthquake Engineering (1361617X)13pp. 157-165
Iranian traditional domes are of the most notable samples of traditional construction in Iran spanning thousands of years, many of which have been standing on seismic parts of the country for many centuries. Structurally, Iranian domes can be categorised into single, double and triple-shell domes. Single-shell domes are the earliest type of domes. The single-shell is the main load bearing part. Double-shell domes consist of two shells, and they are divided into continuous and discontinuous types. In continuous double-shell domes the distance between the two shells is small and shells are connected by brick connectors. In discontinuous double-shell domes there is a considerable distance between the two shells. For the structural stability of some domes meridional walls or stiffeners are built in the space between the two shells. There are also a few domes with three shells. In this paper, structural systems of a number of Iranian historical domes made of masonry materials will be discussed and their structural strength and stability due to dynamic effects of earthquakes will be presented. The document will also explain the structural role of meridional stiffeners in double-shell domes.
Advances in Architecture Series (13681435)20pp. 503-512
The use of wood as a building material in Iran has a long history which dates back to the first millennium. At that time wood was used to make the roofs, beams and columns of some buildings. The extensive use of wood in the construction of large wooden buildings came into practice in the seventeenth century A.D. In that era, huge wooden structures were introduced to the world, some of which are still in existence. A typical example of such buildings is the wooden structure of the Ali Qapu building in Isfahan, Central Iran. The main part of the building, which supports the wooden structure, is made of masonry materials and it was repaired and maintained in the 1960s, but the maintenance of the wooden part remained incomplete. In 1987, a thorough study of the structural behaviour of the wooden structure was completed. Instructions were proposed for repairing the structure according to this investigation. This paper demonstrates the maintenance procedure of the whole building and, in particular, the study of the wooden structure, and it presents instructions for maintenance of the wooden structure.
International Journal of Design and Nature (17443679)1(2)pp. 186-196
The climatic characteristics in different regions of Iran have created architectural design problems. It is advantageous to look at various architectural solutions to such problems. In the hot-dry climate of the indigenous settlements of Iran, particularly interesting design solutions are found. Most solutions, such as high thermal capacity construction materials, compact structure of cities, narrow winding passageways, thick walls, courtyards, internal vegetation, arched roofed chambers, highly elevated wind towers and big water reservoirs, are in conformity with nature and environment. The role of architectural elements is to make use of natural forces such as light, heat, wind and water in design. In this paper, the effects of climatic factors on urban and architectural forms in the hot-dry regions of Iran, climatic design problems and architectural solutions are explained.
Journal of Asian Architecture and Building Engineering (13472852)7(2)pp. 239-245
Today the cultural heritage of humankind is endangered not only by natural catastrophes and the exploitation of resources but also by economic and social problems and institutional weaknesses. Western and Central Asian countries contain a major part of the cultural heritage on the earth, but due to different problems common in developing countries, cultural heritage in such countries suffers from natural and non-natural risks. A lack of public awareness of various types of risks itself worsens the conditions in such countries. It is necessary to clarify the situation within the region regarding different categories of risk, and then considering how to devise measures for heritage sites that are truly endangered at present, as well as how to prepare for risk anticipated in the future. This paper discusses and categorises the risks to cultural heritage in Western and Central Asia.
The Gardaneh Rokh tunnel is being excavated with the length of 1300m it axis striking of N28. The height of tunnel section is 8.6m and its width is 13m. To characteristics of the discontinuities were recorded from 5 outcrops as survey stations. A series of laboratory tests was conducted on the intact rock samples selected from cores taken from two boreholes to get the physical and geomechanical properties. The rock mass along the tunnel enroute was divided into 5 structural zones and were then classified based on the Q and RMR systems. The required support systems were also determined according to the systems. Regarding tunnel stability analysis, the tunnel inlet section as the weakest zone of rock mass located in km 6+300 (structural zone 5) is numerically modelled and analyzed using PLAXIS software with and without support system. The excavation and support installation process was modelled in 3 phases. The results of the numerical modelling show that the crown and sidewalls instabilities are mainly reduced by installation of partial shotcrete support in crown and sidewalls. However, the support installation even in lower sidewalls may not substantially reduce the displacements in invert.
