PSI - Issue 27

Aditya Rio Prabowo et al. / Procedia Structural Integrity 27 (2020) 77–84 Prabowo et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Accidental loads are a common load type in any engineering structure and operation. Its characteristic as an accidental load comes from a wide range possibility of an initial trigger, which may be human error, broken equipment, environmental state, regulation breach, etc. Scholars in civil, mechanical, and marine engineering investigate these phenomena in three major areas, i.e., collision (including crash), grounding (raking and stranding), and explosion. The collision is terminology in marine structures in which two subjects are in contact accidentally. Ship-to-ship collision (Kim, 2020; Prabowo et al. 2017; 2019; Song et al., 2017) and ship-to-offshore installation (Han et al., 2019; Bela et al., 2017, Sha et al., 2019) are given serious attention considering the demand for better safety is continuously growing. Interaction between ship and maritime mammals, such as whales, is a rising topic since the extinction risk of the species is surfacing (Sèbe et al., 2020; Cegarra and Pacheco, 2019). Grounding is similar to the collision case, but the interaction is mainly with the seabed, including rock formation and soil. Most damage is experienced by bottom structures of the ship, which may trigger oil spill and marine pollution. High profile grounding accidents, e.g., Exxon Valdez has been analyzed due to its destructive influence on Alaska water territory (Prabowo and Bae, 2019; Nixon and Michel, 2018). On the other hand, explosions are quite distinct events compared to previous ones, as the target may include not only marine vessels but also offshore installation and land-based structures, such as power plants. The explosion itself is very closely related to fire hazard, and it is commonly triggered due to the chemical reaction of the fire triangle. The fuel may be vary depending on the location of the events. The explosion topic is exciting to be reviewed and discussed since even the highly secure facilities may be subjected to this load type. Taking account to this preliminary discussion, the explosion incident is designated as the main discussion of this work, which several subjects are set as a topic, i.e., historical accident and occurred loss, improvement in assessment methodology, experimental investigation to estimate structural integrity, and numerical approach in observing subject crashworthiness. Assessment of the existing research and report is also considered as a valuable contribution to future development in safety and mitigation measures for both land and marine-based structures. 2. History of explosion accident on land infrastructure Explosion accidents in the recent decade show positive improvement, in which life casualties in an accident is gradually decreasing. Summarized data based on accidents in Chinese mines (Fig. 1a) indicates that the highest death toll occurred in the beginning of millennium for approximately three years with life losses are above 6000 with the rate at least 4.7 death cases per million ton. Nevertheless, advanced technology development after 2010 cannot entirely avoid death cases subjected to the explosion. Causes of the accident are identified as presented in Figure 1b in which the most explosion accident in a coal mine occurred due to leak of gas or gas acts as fuel in a chemical reaction that leads to the accident. Another fuel in the explosion is the coal dust explosion, which is more than 10 cases.

140

70

8000

6

Statistical data: Death toll Death rate

Statistical data:

Frequency Percentage

7000

120

60

5

6000

Accident types: A - Gas explosion

100

50

4

B - Coal and gas outburst C - Coal dust explosion D - Fire E - Mine inundation F - Others

5000

Death Case/10 6 ton 40 60 80

40

4000

3

30

3000

2

20

Case Numbers

2000

1

20

10

1000

0

0

2000 2002 2004 2006 2008 2010 2012 2014 2016 0 0

A

B

C

D

E

F

Accident Types

Year

(a) (b) Fig. 1. Coal mine explosion data: (a) death toll and loss rate from Chinese mines; and (b) frequency of various types of major coal mine accidents in range 1950 – 2015 (Zhang et al., 2018).