# Static and Seismic Responses of Eco-Friendly Buried Concrete Pipes with Various Dosages of Fly Ash
## 6 Static and Seismic Analysis
### Static Analysis of GPC Underground Pipe  
In this study, the static analysis is executed by employing the 7.6-m model of the GPC pipe under static loadings (Figure 5) which are self-weight of the GPC pipe and soil, traffic load onto the ground, internal fluid pressure, and fault displacement in the middle position of the GPC pipe. The main reason for applying such a load combination is to evaluate the most critical statement of the GPC pipe at the failure moment. The self-weight of both the GPC pipe and soil is calculated by applying the gravity (9.81 N) to the created \begin{table}
\begin{tabular}{c c c} \hline \hline
**Material Type** & **No.** & **Density (Kg/m\({}^{3}\))** \\ \hline GPC concrete & 1 & 2420 \\ \hline Internal fluid (Sewage) & 2 & 706 \\ \hline Backfill (Soil type 1) & 3 & 2032 \\ \hline Sidefill and Bedding (Soil type 2) & 4 & 1730 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Material number defined for meshing in ANSYS. FE model in ANSYS. As shown in Table 9, the applied traffic load is used as the uniform contact pressure with the value of 74,137 N/m\({}^{2}\) on the top surface of the backfill soil which is exactly located on the fault considered in the middle position of the GPC pipe as well (Figure 16). In addition, node no. 20 in the element is chosen as the most critical node for this purpose. The internal pressure of 414 KPa is also applied to the internal surface of the GPC pipe model. It is urgent to point out that the mechanical properties of the GPC pipe, such as the compressive strength and density made from PC with diverse dosages of 0, 10, 20, 30, 50, and 70% FA as replacement of PC weight were experimentally obtained in this study (Tables 11-13), along with the 9 parameters related to the nonlinear state of the GPC calibrated in this investigation (Table 14) [3,50]. Figure 16: The settlement of applied static loadings in (**a**) 2D and (**b**) 3D view. The typical vertical displacement of the buried GPC pipe under static loading is presented in Figure 17. Two types of vertical and horizontal displacements are to be assessed for GPC pipes with the variety of FA content with the dosages of 0, 10, 20, 30, 50, 70% as the replacement of PC weight on the directions of the \(y\)- and \(x\)-axis, respectively. It is assumed that the GPC pipe model has no slip in the direction of the \(z\)-axis. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Mix**} & \multirow{2}{*}{**\% FA**} & \multirow{2}{*}{**\% FA**} & \multicolumn{2}{c}{**Compressive Strength (MPa)**} & \multicolumn{2}{c}{**Curing Condition**} \\ \cline{5-6}  & & & **7 Days** & **28 Days** & & \\ \hline PF7030B & 70 & 30 & 8.14 & 14.58 & Water bath at 21 \({}^{\circ}\)C \\ \hline PF5050B & 50 & 50 & 5.97 & 10.55 & Water bath at 21 \({}^{\circ}\)C \\ \hline PF3070B & 30 & 70 & 10.02 & 15.63 & Water bath at 21\({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Compressive strength of various mixes with AS for the percentages of 30%, 50%, 70% FA. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Mix**} & \multirow{2}{*}{**\% FA**} & \multicolumn{2}{c}{**Compressive Strength (MPa)**} & \multicolumn{2}{c}{**Curing Conditions**} \\ \cline{3-6}  & & **7 Days** & **28 Days** & & **Water Bath at 21 \({}^{\circ}\)C** \\ \hline PF10000 & 0 & 21.56 & 31.93 & Water Bath at 21 \({}^{\circ}\)C \\ \hline PF9010B & 10 & 24.99 & 36.63 & Water Bath at 21 \({}^{\circ}\)C \\ \hline PF8020 & 20 & 25.24 & 37.84 & Water Bath at 21 \({}^{\circ}\)C \\ \hline PF7030C & 30 & 18.44 & 31.03 & Water Bath at 21 \({}^{\circ}\)C \\ \hline PF5050A & 50 & 11.68 & 24.53 & Water Bath at 21 \({}^{\circ}\)C \\ \hline PF3070A & 70 & 5.49 & 12.33 & Water Bath at 21 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Compressive strength of various mixes without alkaline solution (AS).