Analysis of the explosion resistance of an I-shaped steel‒concrete composite structure under contact explosion

Abstract

Reinforced concrete and steel structures are commonly used in bridge construction; thus, researchers have conducted relatively comprehensive analyses of their dynamic responses and damage mechanisms under blast loads. However, for a new type of I-shaped steel‒concrete composite structure with various structural performance advantages, there remains a lack of effective experiments and analyses of damage modes. In this paper, three I-shaped steel‒concrete composite specimens are designed and fabricated, and explosion experiments under different explosion scenarios are performed. The experimental results show that under the support of an I-shaped steel plate, the structure has a strong ability to withstand the blast load. The concrete damage area on the rear blast surface is small, and the I-shaped steel plate does not yield under a small explosive equivalent. Based on the experimental results, the dynamic response and failure behavior of the I-shaped steel‒concrete composite structure are numerically evaluated using Autodyn explicit dynamic analysis software. By considering different working conditions and by taking the deformation and damaged areas of the structure as the damage index, the key explosion resistance factors of the structure under contact explosion are studied. Some important structural parameters greatly influence the explosion resistance of the structure, including the thickness of the I-shaped steel plate; however, increasing the strength of concrete does not significantly improve the explosion resistance of the composite structure.

Keywords

steel‒concrete composite structure contact explosion dynamic response failure behavior explosion resistance

Introduction

In recent years, due to the frequent occurrence of terrorist attacks and bridge safety accidents, explosions have become potentially important threats to bridge structures. Once explosions occur, the damage to the bridge system cannot be ignored (Zhang et al., 2014; Yi et al., 2014). An I-shaped steel‒concrete composite structure is a new structure type. The main girder rib structure adopts I-shaped steel beams, and the wing plate ribs use steel concrete slabs. This structure integrates the advantages of steel and concrete materials and has high structural strength, high rigidity and good ductility. Additionally, this structure has a short construction period, low dead load ratio, and fast replacement speed; it is widely used in bridge construction applications. (Nie et al., 2012; Chen et al., 2013). However, relative to the reinforced concrete structure, the I-shaped steel-concrete composite structure has a greatly reduced section size because the steel plate is relatively thin. For this kind of structure under blast load, the following are unclear: the influence of the steel plate support on the overall structure, the damage modes of steel and concrete structures, and the factors affecting the overall explosion resistance of the structure. These factors make the dynamic mechanical response of this special structure more complex than that of simple structures, such as slabs and columns. Additionally, due to the randomness of numerical analyses, relevant experimental verification processes are the most direct and effective methods for clarifying the damage modes of the structure. To date, there is no explosion experiment for I-shaped steel‒concrete composite structures. Therefore, it is an urgent problem to be solved to clarify the dynamic mechanical responses and damage mechanisms of I-shaped steel‒concrete composite structures under blast loads.

For reinforced concrete and steel structures commonly used in bridge construction, many researchers have analyzed the dynamic responses and damage mechanisms of structures under explosive loads and laid the foundation for the anti-blast protection of bridge structures. For reinforced concrete structures, recent research focuses on simple members, such as slabs, beams, and columns. When the reinforced concrete slab is exploded in the near field and the energy is large enough, cracks are generated on the rear blast surface of the slab due to tension; the damage of the rear blast surface is more severe than that of the front blast surface. With an increase in the explosive equivalent, the degree of damage of the concrete slab changes from inelastic deformation to local spalling failure (Yao et al., 2016; Zhao and Chen, 2013). For reinforced concrete beam structures, the structure bends rapidly under a blast shock wave; the blast surface of the beam is damaged by compression and the rear blast surface of the beam is damaged by tension. When the explosive equivalent increases, the overall damage mode of the structure changes from bending fracture to plastic hinge and severe spalling failure (Zhang et al., 2013; Yan et al., 2015). However, under the contact explosion of reinforced concrete columns, the pier column is prone to punching failure at the contact explosion position, the local damage is very serious, and many transverse through-cracks appear in the pier body (Zong et al., 2017; Fujikake et al., 2013). For steel structures, steel columns undergo local buckling and plastic deformation (Nassr et al., 2012). For the closed and thin-walled structure of the steel box, the limited parts around the explosion point cause stress concentration, the plastic area is mainly concentrated in the area around the breach, and the damage to the whole bridge is mainly characterized by local damage (Geng et al., 2017). In a numerical analysis, different element forms and boundary conditions have different dynamic responses to the structure (Liew and Chen, 2004; Chen and Liew, 2005; Lee et al., 2009).

For steel‒concrete composite structures, the existing research mainly focuses on concrete-filled steel tubular (CFST) beams and columns. The performance of the square steel pipe filled with concrete under explosion load significantly improves, and the residual displacement decreases. When the concrete is filled, the steel pipes at the mid-span do not fail (Remennikov and Uy, 2014; Ngo et al., 2015). Fujikura et al. (2008) conducted an explosion experiment on 10 circular CFST columns (one-quarter scale model). The experiment results show that the steel tube concrete columns have good ductility; the structure is mainly dominated by flexural deformation without concrete spalling. Yang et al. (2022) conducted corrugated steel reinforced concrete slab contact explosion experiments. The results show that the damage mode of this structure from the rear blast surface of the concrete transforms from collapse damage into plastic deformation for the steel plate. Zhao et al. (2021) designed and produced a double steel plate concrete slab specimen. The experiments show that the damage mode differs from the reinforced concrete slab, the steel plate undergoes plastic deformation and local buckling, and no concrete splashing occurs. Existing studies have shown that the damage modes and mechanisms of composite components under blast loads differ from those of single steel structures and concrete structures. For the I-shaped steel‒concrete composite structure, there remains no relevant experimental research thus far; additionally, there is a lack of effective experimental verification, even for numerical simulation. Therefore, the existing results cannot be directly applied to evaluations of the damage mechanisms of I-shaped steel‒concrete composite structures. Therefore, the aim of this paper is to analyze the responses and failure behaviors of an I-shaped steel plate-concrete composite structure under blast loading conditions. Three I-shaped steel‒concrete composite structure specimens are designed and manufactured, and explosion experiments under different explosion scenarios are performed. A numerical model is established through the dynamic analysis software Ansys/Autodyn, and the key parameters of the dynamic damage constitutive model of the structure are corrected. After comparing and verifying the numerical analysis results with the experimental results by changing different parameters, such as the explosive equivalent, concrete strength, and steel plate thickness, the key parameters affecting the explosion resistance of the I-shaped steel‒concrete composite structure are obtained, providing a reference for the design of structural anti-blast protection measures.

Experiment

Structural geometry

In this section, three identical experimental specimens are designed and fabricated, and experiments are performed under different explosion scenarios. During the design of the experimental specimen, by taking the steel‒concrete composite beam bridge of the Xixiang-Zhenba Expressway in Shaanxi Province as the engineering background, the original design of the steel‒concrete composite beam section structure is used for scaling. To reduce the experiment cost, the smallest possible component size should be used; however, an overly small size leads to the failure of the steel‒concrete composite connector.

According to the design method of Eurocode 4 for steel–concrete composite beams (Johnson and Anderson, 1993) shear nail push-out experiment recommendations, when the concrete slab thickness of the scaled-down member reaches 8 cm and the corresponding shear nails are configured, a reliable connection between the steel plate and the concrete are guaranteed. By considering the structural stability under explosion, a symmetric structure with concrete top and bottom plates is adopted; I-shaped steel webs with different widths from concrete are used as webs.

The size of the experimental specimen is determined comprehensively. The lengths and widths of the concrete top and bottom slabs are both 560 mm, and the thickness is 80 mm. Double-layer reinforcement is adopted with a diameter of 10 mm and a spacing of 125 mm. The top and bottom plates of I-shaped steel are 560 mm long and 260 mm wide, and the thickness is 16 mm. The diameter of the welding nail shank is 10 mm, and the length is 45 mm. The diameter of the nail head is 22 mm, and the length is 8 mm. The detailed dimensions are shown in Figure 1. The design strength of the concrete is 50 MPa, the steel bar is an HRB400 Φ10 mm threaded steel bar, and the steel plate is Q345 B thick steel. The mechanical properties of the material are shown in Table 1.

Figure 1.

Geometry of the steel‒concrete composite structure.

Table 1.

Material properties of the steel‒concrete composite structure.

Material	Material type	Young’s modulus (MPa)	Compressive strength (MPa)	Yield strength (MPa)	Ultimate strength (MPa)
Concrete	C50	3.5 × 10⁴	50	—	—
Steel bars	HRB400	2.0 × 10⁵	—	400	570
I-beam steel plate	Q345 B	2.0 × 10⁵	—	345	568
Welding stud	/	2.0 × 10⁵	—	494	512

Construction process

To better simulate the explosion resistance of the I-shaped steel‒concrete composite structure, the specimens are manufactured outdoors and transported to the experiment site; the explosion experiment is performed outdoors in open air. The fabrication process of the specimens involves 5 steps: welding the studs to the steel plate, embedding the steel plate into the mold, making and placing the reinforcement mesh, pouring concrete and curing the specimen, and welding the steel web. The construction process is shown in Figure 2. To ensure structural performance, materials are supplied from the factory, and structures are fabricated by the manufacturer.

Figure 2.

Construction process of the test specimens: (a) welding the studs; (b) embedding the steel plate into the mold; (c) making steel mesh; and (d) pouring concrete and welding the steel web.

Experimental conditions

Due to the high energy released by the explosion, it is easy to cause serious overturning and excessive sliding during experimentation. To capture real structural damage, the arrangement of the explosives and the boundary conditions of the specimen are critical. Laminated rubber bearings are placed below bottom plates to form the simply supported boundaries. The explosives explode in contact above the concrete roof. The experimental layout is shown in Figure 3.

Figure 3.

Experimental set up: (a) experimental specimen and (b) RDX.

The results under explosive action are related to various factors, such as the shape and weight of the explosive, which in this experiment is carefully weighed and trimmed into a cuboid shape. The explosives in this experiment are mixtures of hexogen and adhesives, of which 86% is hexogen (RDX). As a highly explosive material, the internal energy is almost 1.5 times that of trinitrotoluene (TNT), and the density is approximately 1890 kg/m³. However, high-energy explosives have high energy density and high explosion temperature and pressure parameters. Using the TNT equivalence factor to evaluate the response to the explosion does not cause much difference. In numerical analysis, TNT is also a commonly used material in the explicit material library, so according to the explosion heat and combustion heat, the equivalent TNT equivalent is converted for subsequent numerical calculations. To quantitatively compare the explosion resistance of composite structures with different explosion scenarios, three explosion scenarios are set up, and the damage modes of composite components at different explosive equivalents and explosion positions are studied. The detonation position of the explosive in explosion scenario 1 is at the center of the concrete roof, and the RDX equivalent is 100 g. The detonation positions of the explosives in explosion scenarios two and three are both at distances that are 1/4 of the way from the center of the concrete roof along the transverse direction of the I-shaped steel; the RDX equivalent is 100 g and 50 g. The detailed explosion scenarios are shown in Table 2 and Figure 4.

Table 2.

Blasting scenarios of the I-shaped steel‒concrete composite structure.

Blast scenario	Explosion location (top of the plate)	The weight of RDX during the experiment (g)	Equivalent TNT weight when calculating (g)	Volume of explosive (mm³)
1	Center point	100	129	40 × 40 × 50 mm³
2	1/4 place	100	129	40 × 40 × 50 mm³
3	1/4 place	50	64.5	40 × 40 × 25 mm³

Figure 4.

Blast scenarios.

Experimental results

After detailed preparatory work, the experimental specimens were contact blasted, and the damage ranges were measured to evaluate the ability of the structures to resist blasting. When the explosion occurred at the center of the concrete roof (blast scenario 1) and the equivalent of the RDX explosive was 100 g, the concrete in the center of the roof suffered punching failure; additionally, a circular blast crater was generated on the explosive-facing surface. The concrete in the center of the blast pit peeled off, and the steel bars were exposed. The damage area was 270 mm × 220 mm, accounting for 18.9% of the concrete roof area. Concrete microcracks were generated from the edge of the self-explosion pit, and the concrete protective layer peeled off due to the loss of synergy of the reinforcement. The rear blast surface suffered greater damage during the explosion than the reinforced concrete slab structure. Under the support of the I-shaped steel plate, the roof concrete of the steel‒concrete composite specimen did not exhibit penetration damage, and only a small range of concrete spalling along the steel bar appeared on the rear blast surface. Longitudinal cracks were generated in the direction of the steel bar, the I-shaped steel plate did not yield, and the structure still maintained a large bearing capacity after the explosion; these phenomena were convenient for rapid repair. The structural damage is shown in Figure 5.

Figure 5.

Structural damage of 100 g RDX explosive equivalent in contact explosion at the center of the top plate. (a) top view and (b) bottom view.

When the explosion occurred at 1/4 of the concrete roof (blast scenario 2) and the RDX explosive equivalent was 100 g, the pressure differential distribution appeared on the explosion-facing surface of the structure. When the center of the explosion source moved laterally, the damage area moved synchronously with the location of the explosion point, and a greater degree of damage ensued than when the explosion occurred at the center. The concrete outside the support of the I-shaped steel plate peeled off in a large area, and penetrating failure occurred. The damage area was 290 mm × 310 mm, accounting for 28.7% of the area of the concrete roof. The outer longitudinal steel bars fell off under the strong shock waves, and the transverse steel bars were bent. Due to the high-frequency vibrations of the steel bars, the cracks in the top plate propagated along the direction of the steel bars. Under the eccentric load, the top of concrete plate was lifted by 10 mm, but it remained connected under the welding stud; the bearing capacity of the structure greatly decreased. The I-shaped steel plate did not yield, and the structural damage is shown in Figure 6.

Figure 6.

Structural damage of 100 g RDX explosive contact explosion at 1/4 of the top plate.

When the explosion occurred at 1/4 of the concrete roof (blast scenario 3) and the RDX explosive equivalent was 100 g, due to the reduction in the explosive equivalent, the damage area of the structure significantly reduced, and a small area of concrete in the explosion center was damaged. The damage area was 230 mm × 200 mm, accounting for 16.1% of the area of the concrete roof. From the damaged area of the lower edge of the concrete slab to the joint position of the I-shaped steel, the crack propagation form was similar to that of the previous two sets of experiments. The I-shaped steel plate did not yield; the structural damage is shown in Figure 7.

Figure 7.

Structural damage of 50 g RDX explosive contact explosion at 1/4 of the top plate. (a) top view and (b) bottom view.

Autodyn analysis

Material parameters

In this section, based on the explosion experiments of steel‒concrete composite specimens, the explicit dynamic analysis software Autodyn is used to perform numerical analysis to verify the rationality of the constitutive model and the applicability of the fluid–solid coupling algorithm. Further research on the internal relationship between various factors, such as explosion position and explosion intensity and the dynamic mechanical response of the structure, is performed.

For numerical analysis, the choice of material parameters plays a decisive role in the reliability of numerical simulation results. When an explosion occurs, the mechanical properties of the material change under the condition of a high strain rate.

In the numerical calculation model, Riedel–Hermaier–Thoma (RHT) is used for concrete, and Johnson–Cook (J&C) is used for the steel plate. The parameters related to the failure of the material are corrected, and the tensile fracture energy of the material under the impact load is set to 100 J·m⁻² to describe the mechanical characteristics of the structure. Assuming air is an ideal gas, the equation of state for an ideal gas is as follows:

p = (γ - 1) ρ E

(1)

where p is the hydrostatic pressure; γ is the adiabatic index; ρ is the mass density; E is the energy density; and the initial energy density of the air is set to 2.068 × 10⁵ mJ/mm³.

The explosive material is TNT explosive, and the state equation adopts the Jones–Wilkins–Lee (JWL) state equation:

p = A (1 - \frac{ω}{R_{1} V}) e^{{- R}_{1} V} + B (1 - \frac{ω}{R_{2} V}) e^{{- R}_{2} V} + \frac{ω E}{V}

(2)

where p is the hydrostatic pressure; V is the relative volume; E is the energy density; and A, B, R₁, R₂, and ω are material constants. The specific parameters of the material are shown in Tables 3–6.

Table 3.

Material parameters of concrete.

Compressive strength (MPa)	Tensile strength	Shear strength	Elastic modulus (MPa)	Shear modulus (MPa)
50	0.1	0.18	32500	13000

Table 4.

Material parameters of the J&C equation state.

Parameter A (MPa)	Parameter B (MPa)	Parameter C	Parameter n	Parameter m
345	424	0.26	0.014	1.03

Table 5.

Material parameters of air.

$ρ$ (g/cm³)	e (J/kg)	$γ$
0.00125	2.068 × 10⁸	1.4

Table 6.

Material parameters of the JWL equation state.

R₁	R₂	A (MPa) (E)	B (MPa) (E)	$ω$	$ρ$ (g/cm³)	V	E (J/kg)
4.15	0.90	3.3785	3.7473	0.35	1.63	1.00	7.0E6

Finite element model

In the preprocessing module of ANSYS, a structural model consistent with the experiment is established. The concrete adopts the solid164 element, the steel bar adopts the beam161 element, and the steel plate adopts the shell163 element. The structure is simulated by Lagrangian elements, and the explosive material and ambient air are simulated by Euler elements. The air domain defines the outflow boundary conditions, which are used for the fluid–solid interaction analysis during the explosion process.

After pretrial calculations and the preanalysis of the experimental results, the analysis model is calculated with structural grid sizes of 5 mm, 10 mm, and 15 mm. The results show that grids that are overly fine may cause convergence difficulties and greatly increase the calculation costs. Grid division may distort the calculation results. The selection of a 10 mm grid size ensures the numerical analysis accuracy and computational efficiency. Due to the short action time of the explosive load, the slip characteristics between the concrete and steel bars are not considered, and the common node contact is used. According to the literature (Wang et al., 2014), the external gap contact algorithm is used in the calculation, and the structural Lagrange solver is used in conjunction.

To obtain the distribution and pressure‒time history of the shock wave on the bridge deck and the overall response of the structure, the numerical model and Gaussian point distribution of the structure are shown in Figures 8 and 9.

Figure 8.

Structural numerical model.

Figure 9.

Arrangement of defined gauges. (a) Concrete roof (b) Steel plate roof.

Comparison between numerical and experimental results

Figure 10 shows the damage modes of the numerical simulations and the experimental results of the specimen under explosion. Since the steel plate does not yield in the numerical simulation or experiment, the analysis results in the numerical analysis show that the damage mode is basically consistent with the experiment. Due to the comprehensive influences of various factors, such as explosive type, explosive shape, detonation conditions, and materials, there are slight gaps between the numerical simulation results and the experimental results. The error results of the three explosion scenarios are 5.8%, 4.1% and 9.8%. The numerical model can reasonably simulate the damage of the structure.

Figure 10.

Comparison of damage modes between numerical simulations and experiments under blast loads. (a) Structural damage of the 100 g RDX explosive in the center of the concrete slab, (b) Structural damage of 100 g RDX explosive exploded at 1/4 of the concrete slab and (c) Structural damage of the 50 g RDX explosive exploded at 1/4 of the concrete slab.

Observing the calculation results shows that the explosive equivalent is 100 g and the initiation point is the center of the concrete slab; the concrete pressure time history curve in Figure 11 shows that the pressure of the explosion shock wave gradually decays with increasing distance from the explosion source. When the explosion shock wave reaches the surface of the structure, the pressure value peaks almost instantaneously before decaying to atmospheric pressure. Immediately afterward, due to the effect of air backflow, the pressure value continues to drop to form a local negative pressure and then slowly returns to atmospheric pressure again. As the explosion distance increases, the maximum velocity of the steel plate increases, the acceleration decreases, and the shock intensity decreases.

Figure 11.

Time history curve during explosion. (a) Pressure time history curves on the concrete roof, (b) Velocity time history curve on the steel plate.

Parameter analysis of the steel‒concrete composite structure

Explosive equivalent

In this section, the effects of the equivalent weight of explosives on the responses and failure behaviors of composite structures are evaluated. Based on the combined components established above, TNT equivalents of 50 g, 100 g, 200 g, 300 g and 400 g are selected. The contact explosion is performed at the center of the concrete roof, and the other parameters are unchanged. Figures 12 and 13 show the failure behaviors of the concrete roof and I-shaped steel plate under different explosive equivalents, respectively. With increasing explosive equivalent, the concrete damage area increases. Radial cracks and annular cracks increase, and the structure suffers more severe fracture damage. For the steel plate, when the explosive equivalent is 50 g and 100 g, the steel plate undergoes no plastic damage.

Figure 12.

Damage of the concrete roof under different explosive equivalents. (a) 50 g (b) 100 g (c) 200 g, (d) 300 g (e) 400 g.

Figure 13.

Principal stress distribution and structural damage of steel plates under different blast equivalents. (a) 50 g, (b) 100 g, (c) 200 g, (d) 300 g and (e) 400 g.

However, when the explosive equivalent is 200 g, the concrete slab almost completely quits working, and the steel plate begins to undergo plastic damage at the mid-span position. As the explosive equivalent continues to increase, the I-shaped steel plate bends significantly, and the plastic damage area increases until the steel plate breaks, and the structure completely loses its bearing capacity. In this process, the vertical displacement of the steel plate has a nonlinear relationship with the explosive equivalent. Table 7 reflects some key parameters of the steel‒concrete composite structure in different scenarios.

Table 7.

Structural responses under different explosion scenarios.

Blast scenario	TNT equivalents (g)	Concrete strength	Steel plate thickness	Concrete damage range (mm²)	Maximum displacement value of the I-shaped steel plate(mm)	Displacement at the center point of the top plate of the I-shaped steel plate (mm)
1	50	C50	16	70 × 50	2.74	2.5
2	100	C50	16	150 × 150	2.56	2.23
3	200	C50	16	280 × 280	11.12	5.82
4	300	C50	16	360 × 360	14.77	5.78
5	400	C50	16	420 × 420	20.45	6.24
6	200	C30	16	300 × 320	11.01	5.65
7	200	C35	16	280 × 295	11.79	5.54
8	200	C40	16	285 × 300	13.13	5.36
9	200	C45	16	190 × 285	10.87	5.93
10	200	C50	8	370 × 380	19.80	8.46
11	200	C50	10	320 × 350	18.27	7.52
12	200	C50	12	300 × 300	14.12	6.58
13	200	C50	14	290 × 300	13.46	5.65

Concrete strength

For a TNT equivalent of 200 g, the strength of the concrete is taken as 30, 35, 40, 45 and 50 MPa, and the other parameters remain unchanged. Table 7 shows that with the increase in the strength of the structural concrete, the damage area of the exploded face decreases slightly, not obviously. There is little change in the damage patterns of the steel plates. Increasing the strength of ordinary concrete cannot significantly improve the composite structure explosion resistance.

Steel plate thickness

In this section, the explosion resistance levels of composite members under blast loads are evaluated by changing the thickness of the I-shaped steel plate as another key structural parameter. The thicknesses of the I-shaped steel plate are considered to be 8 mm, 10 mm, 12 mm, 14 mm, and 16 mm. When maintaining other structural features, the results show that there is little difference in the damage extent of concrete slabs with steel plates of different thicknesses. When the thickness of the steel plate is 8 mm, the steel plate undergoes plastic deformation and damage at the blast crater. As the thickness of the steel web increases, the resistance to deformation increases. The maximum displacement of the steel plate decreases, lateral movement occurs, and the plastic damage area decreases. Figure 14 shows the displacement distribution of the I-shaped steel roof with different thicknesses. The blue area indicates the maximum displacement. The thickness of the steel plate is a significant factor affecting the explosion resistance of the steel‒concrete composite member.

Figure 14.

Displacement distribution of I-shaped steel top plates with different thicknesses. (a) 8 mm, (b) 10 mm, (c) 12 mm (d) 14 mm and (e) 16 mm.

Conclusion

In this paper, three I-shaped steel‒concrete composite structure specimens were designed and manufactured, and explosion experiments in three different explosion scenarios were performed. The response and failure behavior of the composite structure under contact explosion were analyzed. To date, there was no experimental study on this type of structure. Existing research has mainly aimed at numerical simulations and lacks effective experimental verification. The damage results of structures under different working conditions and different structural characteristics were calculated by explicit dynamics Autodyn.

According to the calculation results, the punching failure of the concrete roof under contact explosion formed a circular blast crater, and the damage on the blast surface was more serious than that on the rear blast surface. This phenomenon occurred because under the support of the I-shaped steel plate, the ability of the structure to withstand the explosion load improved, especially when an explosion occurred in the support area of the I-shaped steel plate, and the overall damage of the structure weakened. For the same explosive equivalent, the structural damage area when detonated at the 1/4 distance increased by 43.3%. In addition, the overall response of the structure differed when the explosive yield changed. With an increase in the explosive equivalent, the damaged area of the reinforced concrete slab increased. When the concrete slab was almost completely destroyed, the I-shaped steel plate was bent and plastically damaged at the mid-span position. Eventually, the structure lost its bearing capacity completely. Moreover, the explosion resistance of steel‒concrete composite specimens was mainly affected by the steel plate part, absorbing most of the explosion energy; increasing the thickness of the steel plate reduced structural damage and deformation. However, increasing the strength of ordinary concrete did not significantly improve the explosion resistance levels of composite structures.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Yuan Li

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