# Load Testing and Analysis of a Large Span Through Simply-Supported Steel Box Arch Bridge
## 4 Static Load Test
### Static Load Test Results Data Analysis  
#### 4.4.1 Strain Analysis  
(1) _Arch Rib 1/2 and 1/4 Sections_  
After analyzing the data across various operating conditions, it was observed that under the load of Condition 1, the maximum compressive strain occurred at the 1/2 and 1/4 cross-section positions of Arch Rib 1, which were lower than the calculated values. The verification factor satisfied the code requirements [33]. Furthermore, the maximum relative residual strain rate was below the code limit of 20%. The measured data are presented in Table 2.  
(2) Arch Foot  
The measured data under operating conditions 3, 4, 5, and 6 show that, under Condition 3, the strain at the arch foot is the largest, but it is lower than the calculated value. The verification factor meets the requirements of the code [33]. The maximum relative residual strain rate is less than the code limit of 20%. The measured data can be found in Table 3.  
(3) Tie Beam  
Through the data analysis under various operating conditions, it was found that under Condition 1, the maximum tensile strain occurs at the L/2 cross-section of the tie beam, while under Condition 3, the maximum tensile strain occurs at the L/4 cross-section of the tie beam. The verification factors for all tensile strains are less than 1. After unloading, the maximum relative residual strain rate is less than the code limit of 20%, indicating that the structure is in an elastic working state. The measured data for the tie beam can be found in Tables 4 and 5. Some measurement points exhibited compressive stresses that surpassed the calculated values. This can be attributed to the fact that, during the deformation of the main arch, a portion of the tensile force applied to the tie beams is shared by the main beam, resulting in a decrease in tensile stress. Consequently, when combined with compressive stress, this leads to compressive stress values that exceed the calculated ones. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Measurement Point Location**} & **Measurement Point ID** & **Strain Test Result (\(\mu\)c)** & **Calculated Value (\(\mu\)c)** & **Residual** & **Residual** & **Verification Strain Rate (\%)** & **Factor** \\ \hline \multirow{6}{*}{
\begin{tabular}{c} East Side Arch \\ Ring (L/4) \\ \end{tabular} } & Top Plate & B01 & \(-11\) & \(-18\) & 0 & 0.0 & / \\  & B02 & \(-21\) & \(-26\) & \(-1\) & 4.7 & 0.81 \\  & & B03 & \(-38\) & \(-39\) & \(-1\) & 2.6 & 0.97 \\  & & B04 & \(-42\) & \(-46\) & 0 & 0.0 & 0.91 \\  & & B05 & \(-38\) & \(-59\) & \(-1\) & 2.6 & 0.64 \\  & & B06 & \(-53\) & \(-66\) & 0 & 0.0 & 0.80 \\  & & B07 & \(-23\) & \(-26\) & 0 & 0.0 & 0.88 \\  & & B08 & \(-6\) & \(-18\) & \(-1\) & / & / \\  & & B09 & \(-44\) & \(-46\) & 0 & 0.0 & 0.96 \\  & & B10 & \(-33\) & \(-39\) & 0 & 0.0 & 0.85 \\  & & B11 & \(-57\) & \(-66\) & 0 & 0.0 & 0.86 \\  & & B12 & \(-58\) & \(-59\) & 0 & 0.0 & 0.98 \\  & & C01 & \(-45\) & \(-57\) & \(-1\) & 2.2 & 0.79 \\  & & C02 & \(-59\) & \(-70\) & 0 & 0.0 & 0.84 \\ East Side Arch & & C03 & \(-23\) & \(-32\) & 0 & 0.0 & 0.72 \\  & & C04 & \(-44\) & \(-45\) & 0 & 0.0 & 0.98 \\  & & C05 & \(-5\) & \(-7\) & \(-1\) & / & 0.71 \\  & & C06 & \(-14\) & \(-20\) & 0 & 0.0 & 0.70 \\  & & C07 & \(-55\) & \(-70\) & 1 & / & 0.79 \\  & & C08 & \(-43\) & \(-57\) & 0 & 0.0 & 0.75 \\ West Side Arch & & C09 & \(-40\) & \(-45\) & 1 & / & 0.89 \\ Ring (L/2) & & C10 & \(-30\) & \(-32\) & 1 & / & 0.94 \\  & & C11 & \(-19\) & \(-20\) & 1 & / & 0.95 \\  & & C12 & \(-2\) & \(-7\) & 0 & 0.0 & / \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Measured data of arch ribs under working condition 1. (4) Main Beam  
Under the load of Condition 1, the strain values observed at the top plate and U-rib measurement points of the main beam were relatively low. The tensile stresses at the bottom plate measurement points ranged from 15 \(\upmu\epsilon\) to 44 \(\upmu\epsilon\), with an average strain value of 29 \(\upmu\epsilon\), which is less than the calculated value of 35 \(\upmu\epsilon\). The verification factor was 0.83.