## 2 Experimental Program  
In this study, a total of 20 columns of 200 mm square cross-section and 1000 mm height, were tested. All the columns were reinforced longitudinally with six deformed 12 mm diameter bars. The transverse reinforcement was provided in the form of closed ties of 6 mm diameter bars at 100 mm center-to-center spacing in all specimens, as shown in Figure 1. The deformed steel of 450 MPa yield strength for D12 (12 mm) bars and 300 MPa yield strength for D6 (6 mm) bars were used. The columns were tested under two loading conditions, i.e., concentric axial loading (eccentricity e = 0 mm) and eccentric axial loading with different eccentricities (i.e., eccentricity e = 15, 35, and 50 mm). A clear cover of 25 mm to reinforcement was provided on all sides in the specimens. [PERSON] and [PERSON] (2016) studied the mechanical properties of steel-fiber-reinforced GPC at ambient and elevated temperatures [41]. Three different fractions of steel fiber by volume were investigated (0%, 0.5%, and 0.75%) to find the optimal fraction of steel fiber. The test results showed that compressive strength of GPC specimens were increased by varying the fiber fraction from 0.5 to 0.75% regardless of temperature, and 0.75% was found to be optimal for other mechanical properties. Therefore, 0.75% of fiber fraction by volume has been used in the present study for all the fiber-reinforced GPC columns [41].  
Figure 1: The size and reinforcement detail of the test specimens.  
The columns were divided into three groups depending upon their mix proportions, i.e., CC (conventional concrete columns), GC, and GCD (geopolymer concrete columns). The first group 'CC' comprised of four conventional concrete specimens. In this group, one column was subjected to concentric loading, and the other three were subjected to eccentric axial loading using three different eccentricities, i.e., 15, 35, and 50 mm. The specimens of this group were set as control specimens for the sake of comparison with GPC columns, i.e., GC and GCD specimens. The second group 'GC' comprised of eight square cross-section GPC columns. In this group, all specimens were prepared with FA (50%) and SG (50%) as the source materials. The mix proportions for the prepared columns are shown in Table 1. In the third group 'GCD', QRD was incorporated as a partial replacement (20%) of SG, alongwith SG (30%), and FA content (50%) in all the column specimens.  
The four specimens each in the GC and GCD groups were prepared without steel fibers, and the remaining four in each were reinforced with 0.75% fraction by volume of steel fibers. The details of the specimens, reinforcements and loading eccentricities are shown in Table 2. The dimensions, longitudinal and transverse cross-sections, and reinforcement details of the columns are shown in Figure 1. In the GC and GCD groups, one plain and fiber-reinforced column was subjected to concentric axial load, whereas the remaining plain and fiber-reinforced columns were tested under eccentric axial loading with eccentricities of 15, 35, and 50 mm. All the specimens were named based upon the group (CC, GC, or GCD), loading condition (concentric and eccentric), and fiber fraction (0% or 0.75%). The first part of the specimen name tag represents the group to which the specimen belongs, the second part refers to the percentage of fiber fraction, and the third part represents the loading condition. For instance, GCD-0.75F-50E represents a specimen of third group 'GCD' with 0.75% fiber fraction (0.75F) and tested under 50 mm eccentric axial load (50E).