# Precast Bridges of Bamboo Reinforced Concrete in Disadvantaged Village Areas in Indonesia
## 4 Discussion  
Deformation usually occurs due to shrinkage of concrete, deformation of precast connections, foundation settlement, or due to a static load or dynamic loads on the bridge. In this study, deformation or elastic deformation is a change in shape or change in the angle of the cross-section of the beam or frame due to the distribution of the vehicle loads within the elastic limit measured in the horizontal direction of the cross section. Measurements were made by installing LVDTs (Linear Variable Displacement Transducers) with inductive transducers of type PR 9350 on the horizontal side of the frame and bridge beams, as shown in Figure 30.  
The accuracy of the deformation measurement is very much determined by the calibration of the equipment, the accuracy of the load point of the observation, the conditions of the test site, such as near roads, and human error. Figure 26 shows that the minimum beam deformation occurs when the car axle is right on the neutral line of the beam; this shows that the coupling moment or torque due to the load is a factor that greatly affects the size of the beam deformation. Gravity loads right on the neutral line can reduce the deformation and increase the deflection of the bridge beams. Figures 21 and 26 at the 200 cm coordinates show that when the beam deformation is minimum, the beam displacement is maximum. As shown in Figure 17, Beam 1 is at the coordinates 100 cm and Beam 2 is at coordinates 200 cm. The deformation of the beam increases in line with the track of the car axle; that is, the deformation continues to increase, respectively, at the front car axle and rear car axle. However, the accuracy of the deformation measurements needs attention as to the many determinants of accuracy that exist. Figures 27 and 28 shows that the minimum frame deformation or deformation = 0 occurs when the car axle is directly above the pedestal or approaching the pedestal. Meanwhile, the maximum frame deformation occurs when the car axle is in the middle of the bridge span, which is at coordinates 150 cm. There is a difference in the deformation of the bridge beam and the bridge frame, namely the maximum beam deformation occurs when the load is outside the beam coordinates, while the maximum frame deformation occurs when the load is in the middle of the bridge span or at the 150 cm coordinates. It must be remembered that careful preparation at the time of testing or measurement must be considered so that the data obtained is truly accurate; as shown in Figure 27, the coordinates at 250 cm convey inconsistent deformation data even though the car axle is close to the support. Table 7 shows that the maximum deformation of the bridge frame is 0.13 mm and the maximum displacement of the bridge beam is 0.20 mm. According to the AASHTO [48] and RSNI T-12-2004 standards [49], the allowable limit for the maximum displacement is \(\Delta_{max}\) = L/800 = 3.75 mm and the maximum deformation of the bridge is \(\delta_{max}\) = L/800 = 3.75 mm. Thus, the maximum deformation and displacement that occurs in the precast bridge elements of the bamboo reinforced concrete frame  
Figure 30: Measuring the elastic displacement and deformation. meet the requirements based on AASHTO [48] and RSNI T-12-2004 standards [49]. However, the relationship of load vs. displacement of the beam and the frame results from the field experiments need to be validated or controlled with the relationship of load vs. displacement of laboratory experimental results and simulation results of numerical methods. The simulation in this study used the finite element method (FEM). The simulation of the bridge frame test using the finite element method (FEM) was carried out using the Fortran PowerStation 4.0 program and Surfer 9.8 software [50] based on laboratory test results. Simulations were carried out as control and validation of the experimental data. The bridge frame test simulation was carried out at the first crack load stage, which was 87 kN based on the frame loading capacity of only 100 kN.