Mark Fintel

Abstract: BASED ON THE PRESENT STATE OF THE ART, A PRACTICAL DESIGN PROCEDURE IS PRESENTED TO PREDICT THE CREEP AND SHRINKAGE STRAINS IN COLUMNS OF MULTISTORY BUILDINGS, CONSIDERING THE EFFECTS OF LOADING HISTORY, MEMBER SIZE AND PERCENTAGE OF REINFORCEMENT. ALTHOUGH THE MAGNITUDE OF CREEP AND SHRINKAGE OF PLAIN CONCRETE SPECIMENS MAY VARY CONSIDERABLY, THE FINAL INELASTIC STRAINS IN REINFORCED CONCRETE COLUMNS AND WALLS HAVE MUCH LESS VARIATION DUE TO THE RESTRAINING EFFECT OF THE REINFORCEMENT. ELEMENTS WHICH RECEIVE A SUBSTANTIAL LOADING AT EARLY AGES, SUCH AS PRESTRESSED ELEMENTS AND COLUMNS IN THE UPPER STORIES OF TALL STRUCTURES OR COLUMNS OF LOW-RISE STRUCTURES, ARE PRONE TO HIGHER SHRINKAGE AND CREEP STRAINS. LOWER STORY COLUMNS OF TALL STRUCTURES HAVE CONSIDERABLY SMALLER CREEP AND SHRINKAGE STRAINS THAN COMMONLY ASSUMED AS A RESULT OF: (1) INCREMENTAL LOADING OVER A LONGER PERIOD OF TIME WHICH REDUCES CREEP; (2) A SUBSTANTIAL VOLUME-TO-SURFACE RATIO WHICH REDUCES SHRINKAGE; AND (3) A SUBSTANTIAL PERCENTAGE OF REINFORCEMENT WHICH REDUCES BOTH SHRINKAGE AND CREEP. IN A TALL STRUCTURE THE RELATIVE VERTICAL MOVEMENT BETWEEN COLUMNS AND ADJACENT WALLS CAN CAUSE STRUCTURAL AND ARCHITECTURAL DISTRESS UNLESS PROPER DESIGN AND DETAILS ARE PROVIDED. /AUTHOR/

TL;DR: In this paper, the authors present a design process based on the present state of the art to predict the CREEP and SHRINKAGE STRAINS in columns of multiple-history buildings.