**3.4. Footbridges**

deck consists of a main span of 165 m and two side span of 82.5 m each. The total bridge length is 330 m and the width of the bridge is 30 m. The structural system of the bridge consists of deck, piers, and side support. There are four piers and each has 4.50 m height and 9.00 m × 3.75 m cross‐section areas. All piers are footed on the two raft foundation with bored piles. Two abutments that allow longitudinal direction movement only support the superstructure at both sides [19, 20]. Some views of the bridge with relieve drawings is given in **Figure 9**.

Accelerometer locations are shown in **Figure 10**. The measurements were carried out for at least 60 min. The singular values of spectral density matrices obtained from the processing

vibration data are given in **Figure 11**.

178 Structural Bridge Engineering

**Figure 10.** Accelerometer location and views taken from the measurements.

**Figure 11.** The singular values of spectral density matrices for base isolated bridge.

**Table 3.** Experimentally identified natural frequencies and damping ratios.

**Mode Natural frequencies (Hz) Damping ratio (%)**

 0.993 0.995 2.661 3.952 1.508 1.505 0.958 0.559 2.238 2.241 0.741 0.604 2.853 2.874 0.765 2.145 3.181 3.258 0.371 0.758 4.321 4.298 0.558 0.962

**EFDD SSI EFDD SSI**

Ortahisar and Akçaabat footbridges constructed in Turkey are selected for example. Ortahisar arch‐type footbridge is located in a heavy traffic area in Trabzon, Turkey, and has a main span of 35 m. The footbridge operates as part of a pedestrian public footpath [21]. Akçaabat footbridge also operates as part of a pedestrian public footpath [22]. Some views of the footbridges with relieve drawings are given in **Figure 13**.

**Figure 13.** Some views of the footbridges with relieve drawings. (a) Ortahisar Bridge and (b) Akçaabat Bridge.

Some views from the measurements with accelerometer locations are shown in **Figure 14**. The measurements were carried out for at least 45 min. The singular values of spectral density matrices obtained from the processing vibration data are given in **Figure 15**.

The dynamic characteristics such as natural frequencies, mode shapes, and damping ratios obtained using EFDD and SSI methods in frequency and time domain are given in **Table 4** and **Figure 16**. The first six natural frequencies are obtained between 1.9 and 6.7 Hz. The mode shapes occurred in lateral and torsional forms.

**Figure 14.** Accelerometer location and views taken from the measurements.

**Figure 15.** The singular values of spectral density matrices for footbridges.


**Table 4.** Experimentally identified natural frequencies and damping ratios.

**Figure 16.** The first five mode shapes of the footbridges.

#### **3.5. Steel bridges**

Some views from the measurements with accelerometer locations are shown in **Figure 14**. The measurements were carried out for at least 45 min. The singular values of spectral density

The dynamic characteristics such as natural frequencies, mode shapes, and damping ratios obtained using EFDD and SSI methods in frequency and time domain are given in **Table 4** and **Figure 16**. The first six natural frequencies are obtained between 1.9 and 6.7 Hz. The mode

matrices obtained from the processing vibration data are given in **Figure 15**.

shapes occurred in lateral and torsional forms.

180 Structural Bridge Engineering

**Figure 14.** Accelerometer location and views taken from the measurements.

**Figure 15.** The singular values of spectral density matrices for footbridges.

Bridges are one of the most important engineering structures which are commonly used for interplant and intercity transportation. In Turkey, in earlier days they were designed as narrow and short span with stone and wood materials and to be able to carry light loads. Today, the location of these bridges has been replaced with long span reinforced concrete and steel bridges. According to the General Directorate of Highways data, there are 6447 highway bridges with a total length of 296 km in Turkey.

**Figure 17.** Some views of the steel bridge with relieve drawings.

**Figure 18.** Accelerometer location and views taken from the measurements.

**Figure 19.** The singular values of spectral density matrices for steel bridge.

Eynel steel bridge constructed in Turkey is selected for example. The bridge is located in the Black Sea region of Turkey. It connects to the villages near the two sides of Suat Uğurlu Dam reservoir in the city of Samsun. The construction of the bridge started in 2007 and it was opened to traffic in 2009. The bridge is upper‐deck steel bridge which has arch‐type carriage system with a total length of 216 m. The span of the arch rib is 186 m and it has box‐type section. The height and width of the section is 2.4 and 12 m. The deck is 12 m wide and has a constant thickness of 10 cm [23]. Some views of the steel bridge are given in **Figure 17**.

In **Figure 18**, the accelerometer locations and views during the measurement are presented in detail. The measurements were carried out for at least 60 min. The singular values of spectral density matrices obtained from the processing vibration data are given in **Figure 19**.

**Table 5** and **Figure 20** summarize the dynamic characteristics obtained using EFDD and SSI methods. The first six natural frequencies are obtained between 0.7 and 2.7 Hz. The mode shapes occurred in lateral and transverse forms.


**Table 5.** Experimentally identified natural frequencies and damping ratios.

**Figure 20.** The first six mode shapes of the steel bridge.

#### **3.6. Old riveted bridge**

**Figure 17.** Some views of the steel bridge with relieve drawings.

182 Structural Bridge Engineering

**Figure 18.** Accelerometer location and views taken from the measurements.

**Figure 19.** The singular values of spectral density matrices for steel bridge.

Eynel steel bridge constructed in Turkey is selected for example. The bridge is located in the Black Sea region of Turkey. It connects to the villages near the two sides of Suat Uğurlu Dam reservoir in the city of Samsun. The construction of the bridge started in 2007 and it was opened to traffic in 2009. The bridge is upper‐deck steel bridge which has arch‐type carriage system with a total length of 216 m. The span of the arch rib is 186 m and it has box‐type section. The height and width of the section is 2.4 and 12 m. The deck is 12 m wide and has a constant thickness of 10 cm [23]. Some views of the steel bridge are given in **Figure 17**.

Borçka Old Riveted Bridge constructed in Turkey is selected for example. The bridge, built in 1936, is on the Çoruh River in the town center of Borçka. Total length and width of the bridge are about 114 and 5.30 m, respectively. The main structural system of the bridge has an arch height of 16.30 m from the bridge deck. The bridge girders consist of two edge beams and five middle beams in the longitudinal and transverse directions. The structural elements (arches, pillars, decks, wind connections, etc.) are made out of steel with riveted connections. Bridge is closed to vehicle traffic and it is for only pedestrians [24]. Some views of the old riveted bridge with relieve drawings are given in **Figure 21**.

**Figure 21.** Some views of the old riveted bridge with relieve drawings.

**Figure 22.** Accelerometer location and views taken from the measurement.

**Figure 23.** The singular values of spectral density matrices for old riveted bridge.


**Table 6.** Experimentally identified natural frequencies and damping ratios.

**Figure 24.** The first six mode shapes of the old riveted bridge.

**Figure 21.** Some views of the old riveted bridge with relieve drawings.

184 Structural Bridge Engineering

**Figure 22.** Accelerometer location and views taken from the measurement.

**Figure 23.** The singular values of spectral density matrices for old riveted bridge.

**Table 6.** Experimentally identified natural frequencies and damping ratios.

**Mode Natural frequencies (Hz) Damping ratio (%)**

 0.970 0.968 2.185 1.801 1.352 1.348 0.736 0.926 1.761 1.758 0.962 0.817 2.042 2.041 0.459 0.401 2.726 2.725 0.764 0.707 3.183 3.189 0.432 0.395

**EFDD SSI EFDD SSI**

The accelerometer locations and placements on the deck are displayed in **Figure 22**. The measurements were carried out for at least 60 min. The singular values of spectral density matrices obtained from the vibration data are given in **Figure 23**.

The dynamic characteristics obtained using EFDD and SSI methods are given in **Table 6** and **Figure 24**. The first six natural frequencies are obtained between 0.9 and 3.2 Hz. The mode shapes occurred in lateral, vertical, and torsional forms.
