Study of the influence of compressive strength concrete on columns during the design of a multi-floor building

G M Fregonezi,R D Vanderlei,W W Wutzow

doi:10.1590/s1983-41952019000500008

Abstract

Abstract This work aims to analyze the influence of the compressive strength of concrete columns in the design of a multi-floor building using the CAD/TQS computational tool. The strengths of the columns varied in increments of 5 MPa, from 35 MPa to 90 MPa, with a 35 MPa resistance in the remaining structural elements. Analyses of the horizontal deformability, stability parameters, and optimized sections, as well as quantities and cost of the main materials used (concrete, steel, and formwork), were performed. As a result, a 32% reduction to the total area of the columns was achieved; consequently, a reduction in material quantities and the total cost of the building was also achieved. Thus, greater durability was provided without major costs or loss in structural safety.

Highlights

Technological development and the high competitiveness of the current market result in constantly evolving processes
Mehta and Monteiro [4] explain that the high strength of high-strength concrete (HSC) is due to the effects of the reduction in porosity, heterogeneity and microcracking in the paste and in the transition zone, presenting a different behavior compared to conventional concrete
Reductions in the total costs were observed with respect to fck = 35 MPa and optimized for strength higher than this, reaching just under 3% for fck = 50 MPa and a total average of approximately 1% for the other resistances. These results demonstrate that, the unit costs of HSC are considerably higher (Table 7), when analyzed together with the costs of steel and wood, this cost increase is offset by a reduction in concrete volume and other materials

Summary

Introduction

Technological development and the high competitiveness of the current market result in constantly evolving processes. Among the factors that hinder our understanding of this material are the differences between compressive and tensile strengths, the physical non-linearity (considered by strain-stress diagrams), presence of microcracks, water retention, shrinkage, etc. From a resistance point of view, the water/cement ratio and the porosity are the most important factors, because, independently of others, they affect the porosity of the cement paste matrix and the transition zone between the matrix and the course aggregate [1]. Mehta and Monteiro [4] explain that the high strength of HSC is due to the effects of the reduction in porosity, heterogeneity and microcracking in the paste and in the transition zone, presenting a different behavior compared to conventional concrete. In Brazil, the ABNT NBR 6118: 2014 [7] and the ABNT NBR 8953: 2015 [8] classify concrete structures into two groups of characteristic strength of compression at 28 days (fck, days): Group I (20 MPa ≤ fck, days ≤ 50 MPa) and Group II (55 MPa ≤ fck, days ≤ 90 MPa)

Objectives

Methods

Conclusion