STUDI PERBANDINGAN FAKTOR REDUKSI (f) DARI TAHANAN GLOBAL DENGAN FAKTOR REDUKSI PARSIAL MATERIAL PADA KASUS BETON BERTULANG DENGAN METODE LRFD

Abstract

A reinforced concrete structure can guarantee its safety by giving strength
capacity or design strength more than any combination of working load effect. Design
strength can be obtained by multiplying normal strength with reduction value of f
strength less than one and nominal load is multiplied with the load factor with the value
more than one. It can be written as factored resistance ³ effect of factored loads.
Resistance factor can be expressed in some ways. Such as ACI Building Code was
expressed as fRn ³ D Dn + L Ln, where f was resistance factor and D, and L were
load factor for dead load and live load. Meanwhile CEB explained about resistance
factors with reduction factor directly to its material, fc`/c and fy/s where c and s were partial material of safety factor or under strength material factors for concrete and steel.
Herewith result from concrete material variability, the variety coefficient compression
strength of concrete ( Wfc) had great influence to the reduction factor both global
reduction factor from ACI and material partial reduction factor from CEB. The increase
of load ratio (L/D) would add space between factor of dead load (D) and live load (L)
were wider. With the increase of the value index gave the increase of safety condition.
The result of the study was obtained that the influence of small dimension was to the
global reduction factor and material partial reduction factor. After comparing the results
obtained from the calculation method using global reduction factor (ACI) with material
partial reduction factor (CEB), it could be drawn a conclusion that for beam and coloum
using global reduction factor, its capacity to hold dead load was more than 13 % than
material partial reduction factor.