China
Africa
Explore chapters and articles related to this topic
Earthquake activity
Published in F.G. Bell, Geological Hazards, 1999
The most serious direct effect of an earthquake in terms of buildings and structures is ground shaking. As pointed out in Section 3.4, the type of ground conditions are important in this regard, buildings on firm bedrock suffering less than those on saturated alluvium. Nonetheless, buildings standing on firm rock can still be affected, so that susceptible buildings should not be located near to a fault trace. The type of construction also influences the amount of damage that occurs. Poorly constructed buildings and those that are not reinforced undergo the worst damage. Indeed, strong ground shaking can reduce cities to rubble if buildings are weakly constructed. For instance, on 29 February 1960, hundreds of old unreinforced masonry buildings and many younger but poorly constructed reinforced concrete structures were destroyed in Agadir, Morocco, by an earthquake of magnitude 5.9, intensity VII. Approximately 14 000 persons met their death out of a population of 33 000. A number of factors can influence the death toll in a major earthquake. The time of day determines whether large numbers of people will be in offices, factories or schools. Property losses can be enormous in metropolitan areas and this tends to rise dramatically with urban development. Fortunately, the ratio of loss of life to property damage tends to decline as more earthquake-resistant structures are built. In the Tokyo earthquake of 1 September 1923, 128 000 houses were destroyed by the earthquake shock. However, a further 447 000 were burnt out.
The influence of material variability on failure mode control of steel frames
Published in A.S. Elnashai, European Seismic Design Practice, 1995
G.M. E. Manzocchi, M. Chryssanthopoulos, A.S. Elnashai
As discussed above, the performance of earthquake resistant structures is dependent on the ability to sustain deformations into the inelastic range whilst maintaining overall structural stability and without exceeding the ductility supply of the individual members. Thus the response criteria obtained via static analysis are specifically chosen to measure this capability. In this study, the effects of strain hardening are considered by using a bilinear elastic-strain hardening material model for the steel stress strain law. This model is implemented at the fibre level of the steel section within ADAPTIC, and thus the spread of plasticity within a member is modelled explicitly. As a result of material strain-hardening, the static load-deflection curve may not always degrade following the formation of an overall mechanism. In such cases it is may not be possible to obtain the system ductility based on degradation of the load-deflection curve. Therefore, the system ductility is here derived in all cases by considering the ultimate rotation capacity of the plastic hinge zones. This criterion for hinge rotation capacity is based on that derived by Kato (1989) where hinge rotation is assumed to be limited by the onset of inelastic buckling in the section, and includes the effects of interaction between flange and web buckling. This criterion is a function of the randomly distributed yield stress and hence variability in the rotation capacity is also a factor that is accounted for in this study.
A Simplified Mechanical Approach for a Large-Scale Seismic Vulnerability Assessment of the Algerian Masonry Buildings
Published in International Journal of Architectural Heritage, 2022
In order to perform seismic scenarios for Algerian masonry buildings at a large scale, the N2 method is herein adapted and applied. This reduction factor method is a fast nonlinear method originally developed by Fajfar (2000) and is used nowadays for almost every building type. This method has been integrated into European standards for the design of earthquake-resistant structures, such as Eurocode 8, to better control the damages caused by earthquakes (Adriana, Ivan, and Dragan 2018). Through this method, the seismic performance of buildings is identified by means of an intersection point between the capacity curve of an equivalent nonlinear SDOF system and the earthquake demand curve, which is reduced to include the energy dissipation of the buildings. Both curves should be represented in a spectral acceleration versus displacement domain. The following relationships (Equations 8–10) are used to relate the spectral displacement Sd to the spectral acceleration Sa (Fajfar 2000):
Development of structural testing equipment for impact and complex loading
Published in Journal of Structural Integrity and Maintenance, 2021
Experimental testing plays a significant role in developing earthquake-resistant structures. Among all the structural components, structural columns (in general, including structural elements carrying both vertical and horizontal loads) receive most attention, as failures of such structural elements result in devastating collapse of structures under severe earthquake attacks.