THE SUPPORT OF THE MINISTRY OF SCIENCE AND HIGHER EDUCATION UNDER THE GRANTS N AND R IS KINDLY ACKNOWLEDGED

Outline: - Motivation - Introductory remarks - Objectives and numerical analysis: - Structural safety - Public safety - Results - Conclusions THE SUPPORT OF THE MINISTRY OF SCIENCE AND HIGHER EDUCATION UNDER THE GRANTS N AND R IS KINDLY ACKNOWLEDGED

Motivation: The elements of critical infrastructure are often under explosive risk, and must be protected - Airports - Railway Stations - Trade & Business centers - Banks - Fuel depots and storages - Government agencies Objective: Pressure distribution and structural damage

Introductory Remarks: - The office structure (the main structure) is subjected to explosion - The analysis demands a compelx caluculations (complexity, dof). This time the general problem of safety is uncoupled into three jobs: A) STRUCTURAL ELEMENT SAFETY (steel column) B) GLOBAL STRUCURE SAFETY (whole RC structure) C) PERSONEL SAFETY (pressure evolution)

Introductory Remarks: Structural safety criteria 1. Acceleration for equipment 3g, t > 1200s; 5g, t > 60s; 8g, t > 10s; 18g, t > 0.2s; 25g, t > 0.001s; 60g (database server) 2. Stress & Strain for structural elements Depending on material kind, compression, tension, strain rate, loading peaks and impulses Public safety criteria Human tolerance to the blast output of an explosion is relatively high. However, the orientation of a person (standing, sitting, etc.) is really important. The pressure tolerance for short-duration blast loads is significantly higher than that for long-duration blast loads. There are used two separate criteria, in agreement US standard i.e. Unified Facilities Criteria (UFC ), for assessment public safety. 1. Eardrums rupture for overpressure above [Pa], and impulse duration 0.2 [Pa · s] 2. Lung damage depends on overpressure-impulse and person weight

Objectives and Numerical Analysis: Structural safety Case A – Steel column Objective: To find a limit value of scaled distance (Z) for safety design Geometry Steel column (H-section), IPE300, 3m high, fixed-joint boundaries Material Johnson-Cook model for stainless steel [Akbari, Joodaki 2005] Numerical job 72e3 S4R elements (0.005x0.005m 2 ), time of the analysis is 52e3s (1CPU 2.6XEON) 1. Initial Static loading (10s) Dominant is vertical force (effort below 90%) 2. Explosive loading CONWEP (0.01s) 0.1kg of TNT in 0.25m distance 3. Assessment of limit loading (10s) Upper boundary movement (1cm/10s) F0F0 F0F0 F0F0 explosive loading Δ

Objectives and Numerical Analysis: Structural safety Case A – Steel column Results IPE300 The results for the 1kg of TNT in 0.25m distance The FE mesh is decreased in to 0.05 by 0.05 m 2 element size

Objectives and Numerical Analysis: Structural safety Case A – Steel column Different failure criteria for steel elements

Objectives and Numerical Analysis: Structural safety Case A – Steel column Results IPE300 for close (distance <1m) explosions The different high of the columns are analyzed, under different explosions (4x16 examples) Z min = 0.22Z min = 0.16 Limit vertical load must be lower than 90% of limit loading Maximum support rotation for beams is 2 deg (TM5-1300)

Objectives and Numerical Analysis: Structural safety Case A – Steel column Results HEB600 for close explosions (distance <1m) The different high of the columns are analyzed, under different explosions (3x19 examples) Z min = 0.14Z min = 0.17 Limit vertical load must be lower than 90% of limit loading Maximum support rotation for beams is 2 deg

Objectives and Numerical Analysis: Structural safety Case B – Whole structure Objective: General assessment of whole structure safety The explosive pressure is subjected to reinforced concrete structure. The homogenous RC material is loaded by the overpressure. Geometry RC structure 30x30m 2 and 20m high (6 floors) Material Elastic RC concrete with stress limit (FE deletion) Ideal Gas Equation of the state for the Ambient Air JWL Equation of the state for the Explosive Numerical job EOS ~5e6 EC3D8 finite elements (0.2x0.2x0.2m 3 ), Def. ~2e6 C3D8 finite elements (0.1x0.1x0.1m3) Time of the analysis is 26h (8CPU 2.6XEON) 1. Initial Static loading 450kg/m 2 2. Explosive loading CEL 1000kg of TNT in 2.0m distance form the frontal facade

Objectives and Numerical Analysis: Structural safety Case B – Whole structure

Objectives and Numerical Analysis: Structural safety Case B – Whole structure The results FE failure criteria Compression -80.0MPa Tension +1.0MPa t=0.001s after detonation t= 0.01s after detonation

Objectives and Numerical Analysis: Structural safety Case C – Public safety Objective: Overpressure distribution inside a building Geometry Rigid geometry of the building simulates the reflection of the blast wave Material Ideal Gas Equation of the state for the Ambient Air JWL Equation of the state for the Explosive Numerical job ~5e6 C3D8 finite elements (0.2x0.2x0.2m3), time of the analysis is 8h (8CPU 2.6XEON) 1. Initial Static loading 450kg/m2 2. Explosive loading CEL 100kg of TNT in 2.0m distance form the frontal facade

Objectives and Numerical Analysis: Structural safety Case C – Public safety The blast wave reflection from the rigid body

Objectives and Numerical Analysis: Structural safety Case C – Public safety Personnel safety criteria (TM5-1300, UFC), for SI units Lung DamageEar drums rupture

Objectives and Numerical Analysis: Structural safety Case C – Public safety Results The limit value for personnel safety has been set on Pa (grey elements) The blast wave front (>150000Pa) propagates through the structure

Conclusions A1. Limit values of scaled distance are obtained for steel columns A2. Scaled distance is different for close and far field explosive action A3. Further study enforces using of advanced material behavior B1. Analysis of whole RC structure + steel reinforcement ! B2. Air discretisation vs. the results C1. Personnel safety is analyzed, what about fragmentation ?

Thank you for your attention ! Poznan University of Technology