PROCEDURE AND SPECTRA FOR ANALYSIS OF RC STRUCTURES SUBJECTED TO STRONG VERTICAL EARTHQUAKE LOADS

Abstract

In view of the compendium of field evidence and supporting analysis work indicating the possible damaging effects of vertical earthquake ground motion, this paper addresses the problem of code-type vertical force calculation. In light of recent engineering seismology studies of the relationship between vertical and horizontal peak ground acceleration, the inadequacy of the 2/3-rule depicted by codes is highlighted. A simple piece-wise linear relationship is proposed and shown to represent existing strong-motion measurements adequately. Bilinear and inelastic spectra are derived and studied. It is demonstrated that net tensile forces and displacements may ensue, thus eroding the shear resistance of RC columns. A simple procedure is outlined whereby modal analysis may be employed to estimate conservatively vertical earthquake forces on buildings. Finally, areas of further exploration and refinement are identified.     

ENERGY-BASED TECHNIQUE FOR SEISMIC PERFORMANCE ASSESSMENT OF INTERIOR BEAM-COLUMN JOINTS

For investigating the seismic behaviour of monolithic beam-column joints, a new technique of assessment of joint performance, termed the Shear Deformation Energy Index, is presented in this paper. Previous research efforts in this field were evaluated and the relative merits and drawbacks of each approach were highlighted. Primary variables influencing the seismic behaviour of joints were studied in the experimental phase of the current study. This included pseudo-static testing of nine interior beam-column sub-assemblages with different joint configurations. The parametric investigation of primary variables was complemented by studying the behaviour of specimens of eight different experimental programmes. For easy application of the technique in design practice, the Index is graphically represented versus its main variables in a design chart, referred to as the Performance Chart.     

DEFORMATION-CONTROLLED EARTHQUAKE-RESISTANT DESIGN OF RC BUILDINGS

A procedure for deformation-controlled, or displacement-based, seismic design of multistorey RC buildings is proposed, implemented and applied for the full design of a four-storey RC structure. It is integrated into the overall structural design, along with the design for the non-seismic actions and consists of a ULS verification against the conventional strain limits for a frequent “serviceability” earthquake and of proportioning the compression reinforcement and the transverse reinforcement of critical regions of members to meet the member peak inelastic chord rotation demands under the “life-safety” seismic action. Quantitative rules and expressions are proposed for the estimation of (a) mean and upper-characteristic peak inelastic chord rotation demands, through appropriate linear-elastic analyses, and (b) mean and lower-characteristic values of member ultimate chord rotations, in terms of member geometric and material data.     

Nikolay Vasil'yevich Morozov

Moscow University geographers commemorate a fellow faculty member who died in 1949 after having been barred from teaching and from publication of his methodological articles in the last 15 years of his life. The appraisal of N. V. Morozov is followed by a previously unpublished article on relationships between society and nature, designed to support the “unified geography” position in the current ideological dispute.     

The Development of Geography in the Soviet Republics of Transcaucasia

A review of geographic research in Transcaucasia during the 50 years of Soviet rule. A great diversity of natural conditions within a relatively limited area has made the region a miniature laboratory and testing ground for a variety of geographic concepts, especially in climatology and hydrology.     

Principles of a Territorial Differentiation of Retail Prices

A system of territorial differentials in retail prices for consumer goods in the Soviet Union is considered essential as long as regional physical and other geographic differences produce cost differentials in production and transportation. It is suggested that the present system of three price zones be revised for individual food products to take fuller account of distance between producing and consuming areas.     

Practical Problems in Physical Geography

Before physical geographers will be able to play a more effective role in applied research, a number of methodological problems should be investigated. Work must be done on the kinds of relationships that exist between the physical environment and engineering structures. Physical phenomena of economic significance must be translated into commensurable technical and economic units that can be taken into consideration in the design of engineering objects.     

Problems of Long-Term Geographic Prediction

A program of geographic prediction up to the year 2000 is proposed for inclusion in the teaching and research plan of the Geography Faculty of Moscow University. Three aspects are distinguished: (1) specific forecasting of changes on the face of the earth and in the use of resources, (2) the elaboration of methods of geographic prediction, and (3) prediction of future trends in the science of geography. The three key factors in specific geographic prediction are the hydroclimatic, the anthropogenic, and the resource factor. The principal method of prediction should be the study of chain reactions, of cause-and-effect relationships, allowing for flexible multivariate forecasts. In the science of geography, periods of differentiation and integration are found to have alternated at periods of 25 to 30 years. The most promising tendencies in geographic research are the hydroclimatic approach, the new synthetic disciplines, economic geography, and integrated mapping of geographic phenomena.