Excel spreadsheet for the article
Gambhira
Bridge Collapse: slab fell. Time: 9 July 2025, 7:30 AM IST 2hrs UTC.
By
Ramaswami Ashok Kumar, B.E.,M.E., Negentropist, Bombay Sarvodaya Mandal, 299,
Tardeo Road, Nana Chowk, Mumbai-400007.
Photo Courtesy Reuters.
Copyright © 2025 Ramaswami Ashok Kumar.
Table 1: Ball park estimates of bridge being hit by world dam dynamics.
Table 1:Bridge Collapse preliminary assessment based on world dam Dynamics
caused earthquakes MM 0+ on (9 July 2025 from 0 hrs to 2:06 h UTC.
The approximate analysis for a ball park estimate of the
disaster.
The bridge slab was assumed to be of 15m by 15m by 1m for
which the acceleration vertically down was measured.
The bridge collapse is examined on the basis of
earthquakes worldwide caused by the world’s dams. The period was from 00:00:00
hrs UTC on 9 th July 2025 to 9th July 2025T2:06:18 Z. The bridge
collapsed around 2:06:18.1Z. Note that in the dam era almost all the
earthquakes worldwide are caused by the world’s dams. Thus the earthquakes
during the study period are used as proxy for the dam content changes during
the period.
The heat input required around the collapsed Gambhira
bridge to raise the temperature of the structure by 1 K is taken to be 1.55E+13 J/degree Kelvin. The centre of gravity of
the world’s dams during the hydrological year 2024-2025 is taken to be 25.80571,116.2424,
same as the average deviation of the earthquakes from the mean during the
hydrological year. The earthquake magnitude expressed in moment magnitude and
location parameters are got from the earthquake data as published by
usgs.gov.in at earthquake search data at USGS website. At any earthquake caused
by the dams the stress which released the earthquake of stated magnitude, the
seismic moment, is computed and five times the seismic moment is taken as the
stress at the point prior to release of the earthquake. The distance between
the earthquake hypocentre and the centre of gravity of dams is computed and
from these data the dam content change worldwide which caused this earthquake
is determined. This dam content change is computed for each earthquake in the
stated study period. The shear stress limit for concrete is assumed to be
2800000 N/m^2. Knowing the dam content change for the earthquake, the force
applied by the world’s dams at the earthquake point is determined. Knowing this
force, the force at the bridge break point is assumed the same. With the value
assumed for the shear stress limit for concrete, the shear area for the slab is
computed for each earthquake whose dam content change and associated force
applied on the slab has been just computed. This way the shear area on the slab
for each earthquake caused by the world’s dams is determined(Table 1). The max
shear area for the slab turns out to be 96.66 m^2 and the mean was 3.11 m^2. The mean acceleration of the bridge slab
every dam content change was a mammoth 22.8 m/s/s. The initial mass of the slab
which broke away was assumed to be of dimensions 15mx15mx1m.
Excel spreadsheet for the above estimate
https://docs.google.com/spreadsheets/d/1cctoM4NTVdjFvNYgwJPDtHN3lztUBYKg/edit?usp=drive_link&ouid=105333656754945226707&rtpof=true&sd=true
No comments:
Post a Comment