Towards Damage-Based Design Approach for RC Bridge Columns Under Combined Loadings Using Damage Index Models

This article investigates a damage-based design approach for circular reinforced concrete (RC) columns under combined bending, shear, and torsion using decoupled damage index models. The combination of bending moment, shear, axial, and torsional loading affects the structural performance of bridge columns with respect to strength, deformation capacity and progression of damage. The damage index model proposed here permits decoupling these combined actions according to various damage limit states. This work evaluates the interaction between bending and torsional damage indices in terms of progression of damage. It also investigates the effects of the transverse reinforcement ratios and shear span. Based on experimental and analytical results increase of torsion amplified the progression of damage. The increase in transverse reinforcement ratio was found to have delayed the progression of damage and to have changed the torsional dominated behavior to flexural dominated behavior under combined bending and torsion.     

Stochastic Modeling of Earthquake Scenarios in Greater Tehran

Tehran, the capital of Iran, with millions of inhabitants, has been affected several times by historical and recent earthquakes that confirm the importance of seismic hazard assessment for the area. The main objective of this article is to present a probabilistic procedure to construct time series compatible with the source-path and site reflecting the influence of different magnitude events at different distances that may occur during a specified time period. A Monte Carlo approach is used to generate numerous synthetic catalogs for the evaluation of the probabilistic seismic hazard in greater Tehran over hard rock site for a return period of 475 years. The disaggregation of the seismic hazard is carried out to identify hazard-dominating events and to associate them with one or more specific faults, rather than a given distance. The stochastic finite-fault technique based on region specific seismic parameters is used to generate time series of earthquake scenario.     

Effect of Topology Irregularities and Construction Quality on Life-Cycle Cost of Reinforced Concrete Buildings

Life-cycle cost (LCC) analysis entails consideration of building performance throughout the structures’ life. The impact and interaction of topology irregularities and construction quality (CQ) on LCC, however, are often ignored and require a more detailed evaluation. In this article, different levels and interaction of soft story (SS) and CQ are analytically modeled to quantify corresponding fragility curves and LCC (by considering hazard level, limit state cost, and probability of being in different damage states). The proposed method is illustrated with a three-, six-, and nine-story reinforced concrete building located in Vancouver (located in west coast of Canada).     

Numerical Investigation of Residual Strength and Energy Dissipation Capacities of Corroded Bridge Members Under Earthquake Loading

Recent damage examples of aged steel bridge infrastructures around the world are so alarming. They intensified the importance of careful evaluation of existing structures for the feasibility of current usage and to ensure public safety. Corrosion and fatigue cracking may be the two most important types of damages in aging structures. Furthermore, recent earthquakes demonstrated potential seismic vulnerability of some types of steel bridges. Corrosion and its effects can trigger the damages caused by earthquakes, and it will be vital to understand the behavior of existing steel bridges which are corroding for decades in future severe seismic events as well. This article comprises the results of nonlinear FEM analysis of many actual corroded plates with different corrosion conditions and proposes a simple and reliable methodology to estimate remaining seismic strength and energy dissipation capacities by measuring only the minimum thickness of a corroded surface, which can be used to make rational decisions about the maintenance management plan of steel infrastructures.     

Derivation of New Equations for Prediction of Principal Ground-Motion Parameters using M5′ Algorithm

In this study, M5′ model tree is used to develop a model for prediction of peak time-domain strong ground motion parameters. The main advantages of model trees are that can be easily developed and their formulas are simple and understandable. Selected data from Pacific Earthquake Engineering Research Center (PEER) are used to train the proposed model. Earthquake magnitude, earthquake source to site distance, average shear-wave velocity, and faulting mechanisms are used as input parameters. The developed M5′ based formulas are compared with those of well-known empirical and soft computing based models. The accuracy of the model is evaluated by statistical error parameters.     

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.     

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.     

The Present State of Medical Geography in the USSR

A review of the present state of Soviet medical geography based on an analysis of papers presented at the Second National Medical Geography Conference held in Leningrad in November, 1965. The authors, representing four departments of the Geography Faculty of Moscow University, stress geophysical and geochemical causative factors of human disease and the contributions being made by medical landscape science in relating environmental prerequisites to particular diseases.