PSI - Issue 14

Angitha Vijayan et al. / Procedia Structural Integrity 14 (2019) 696–704

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Angitha Vijayan et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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This is in agreement with the findings of Shahabpoor et.al (2017) where same test was repeated with another group of participants without changing the crowd size. Hence, for further analysis, crowd properties are obtained from properties of an average person given in Table 2 without distinguishing between the characteristics of different individuals in the crowd.

Table 2. Input properties of an average person. Property Value Mass (kg) 70 Stiffness (N/m) 23360 Damping (Ns/m) 770

Table 3. Comparison of analytical results of CS system for assumed crowd characteristics of an average person with experimentally obtained crowd characteristics.

Results of CS system for crowd characteristics given by Shahabpoor et.al (2017)

Results of CS system for assumed crowd characteristics of an average person

No. of people on the structure

f cs (Hz)

ζ cs (%)

f cs (Hz)

ζ cs (%)

Walking along the span 3 4.448

1.00 1.55 2.20 1.80 2.92 3.00

4.448 4.456 4.467 4.453 4.470 4.496

1.41 2.00 2.81 1.80 3.02 4.62

4.460 4.480

6

10

Walking in a circle at midspan 3 4.454

4.485 4.520

6

10

4. Analysis of crowd structure system

The geometric and material properties of the structure are tabulated in Table 4. The geometry is kept same as that of the structure used for validation. Material properties are assumed for a typical RC structure.

Table 4. Input properties of structure. Material property Value

Geometry (Shahabpoor et al., 2017)

Value

2500 2.5 × 10 10 Breadth (m) 0.6 Depth (m) Length (m)

Density (kg/m 3 )

10.800

Young’s Modulus (N/m 2 )

2.000 0.275

Damping ratio (%)

Table 5. Range of vertical frequency for various activities (Bachmann et al, 1995). Activity Frequency (Hz) Walking 1.6-2.4 Running 2.0-3.5 Bouncing 1.5-3.0

Table 6. Results from modal analysis of empty structure. Modal property Mode 1 Mode 2 Natural Frequency(Hz) 3.356 9.492 Modal Mass (kg) 7425 7425