## 1 Introduction  
Explosions have historically been a preferred method of terrorists for a variety of reasons. The main reason for this preference is that it is easy and fast in terms of process management and implementation. Bomb-laden vehicles are preferred as they can reach the target easily and the weight of the charges that they carry can be increased in proportion to the size of the vehicle. The damage to the structures because of the explosions varies according to the size of the explosive, the standoff distance, the characteristics of the structure and many other parameters [1]. Many researchers have conducted experimental and numerical studies on the estimation of blast loads. First of all, numerical studies were conducted to estimate the pressure of the blast load and various formulations were developed [2; 3; 4; 5; 6]. The usage of all kinds of tools and equipment with explosion risk, materials used in the defence industry, wars, terrorist activities, etc., all require explosion safety. For this reason, various regulations and reports related to explosion have been issued in many areas. Design of Structures to Resist Nuclear Weapons [2], Design of Structures to Resist the Effects of Accidental Explosions (Army Technical Manual) [7], Design of Blast Resistant Buildings in Petrochemical Facilities [8], and Unified Facilities Criteria [9] are various reports and regulations used nationally and internationally in the definition of blast loads. FEMA 426 (Risk Management Series Primer for Design of Commercial Buildingsto Mitigate Terrorist Attacks, Providing Protection to People and Buildings) [2], FEMA 427 (Risk Management Series Primer for Design of Commercial Buildings to Mitigate Terrorist Attacks, Protecting Office, Retail, Multi-Family Residential, and Light-Industrial Facilities) [1], FEMA 452 (Risk Assessment--A How-To Guide to Mitigate Potential Terrorist Attacks Against Buildings) [10], FEMA 453 (Risk Management Series Design Guidance for Shelters and Safe Rooms) [11] and FEMA 430 (Risk Management Series Site and Urban Design for Security Guidance Against Potential Terrorist Attacks) [3] are published guides on the explosion of terrorist attacks. [PERSON] and [PERSON] [12] wrote a report containing blast load calculations. These regulations and reports are sources for estimating explosion effects on structures. Table 1 shows the estimated damage table given in FEMA 426. Minimum safe distances needed for preventing injury and damage for safe design and risk management of potential terrorist attacks are given in FEMA 430 (Table 2) [3]. In addition, safe following distances for explosive transport are determined by considering the maximum number of explosives that cars can carry based on their luggage capacity (Table 3) [13]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Incident Overpressure** & **Damage** \\
**[kPa]** & **Damage** \\ \hline
1.03–1.52 & Typical window glass breakage \\
3.45–7.58 & Minor damage to some buildings \\
7.58–12.41 & Panels of sheet metal buckled \\
12.41–20 & Failure of concrete block walls \\
34.48+ & Collapse of wooden-framed buildings \\
27.58–48.26 & Serious damage to steel-framed buildings \\
41.37–62.06 & Severe damage to reinforced concrete structures \\
68.95–82.74 & Probable total destruction of most buildings \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Typical overpressure damage [1]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Injury and/or Damage** & **Stand-Off (m)** & **Stand-Off (m)** \\
**(226 kg TNT)** & **(2260 kg TNT)** \\ \hline Threshold of failure of concrete columns & 9 & 18 \\ Potentially lethal injuries & 45 & 105 \\ Injuries from wall fragments or to people in the open & 45–75 & 105–150 \\ Severe glass wounds (glass with applied film) & 75 & 200 \\ Severe glass wounds (unprotected glass) & 150 & 300+ \\ Minor cuts & 240 & 300+ \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Injury or Damage Related to Stand-off [14].