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This study investigates the seismic performances of a precast bridge made of geopolymer concrete (GPC) with fibre-reinforced polymer (FRP) reinforcements subjected to cross-fault ground motions. A numerical model was developed and verified against experimental results from a previous study and then used to evaluate the bridge's performances under earthquake excitations. The study found that a simplified model was able to reliably capture the failure pattern and displacement response of the bridge, reducing simulation time significantly. Additionally, the numerical results indicated the combination of torsional and flexural cracks was the primarily damage mode of the columns, which was not observed in the experimental test. This study also revealed that while the performances of the bridge using ordinary Portland cement (OPC) and GPC were similar under low ground excitations, GPC columns were more susceptible to brittle failure under higher ground excitations due to their brittleness. The use of FRP reinforcements led to similar displacement response as steel reinforcements under low ground displacement excitation, although severe flexural and shear damages on the column of Bent 2 were observed due to the lower elastic modulus and shear resistance of Basalt FRP material than steel. To address the disadvantages of brittle GPC and low-modulus of basalt FRP reinforcements, it is suggested to reinforce GPC with fibres and/or increase stirrup ratios if green GPC and corrosion-resistant basalt FRP reinforcements are used to construct bridges for seismic resistance. • Geopolymer bridge with FRP reinforcement under cross-fault ground motions. • Simplified FE model can reliably predict the structural responses. • Numerical results indicate failure mode, not found in test. • Compare bridge with GPC and FRP reinforcement with conventional bridge. • Specify key pros and cons of bridges with GPC and FRP reinforcement [ABSTRACT FROM AUTHOR]

In order to promote the use of new sustainable steel fibers (SF) reinforced coal gangue aggregates (CGA) concrete, impact tests were performed in this paper. The impact resistance of steel fiber-reinforced coal gangue concrete was investigated using a self-developed drop-weight facility. The test variables were the CGA replacement rate (0 %, 50 %, and 100 %), the SF volume content (0 %, 0.75 %, and 1.5 %), and the drop height of the drop-weight (0.5 m and 1.0 m). Using 15 kg of hard steel as a drop-weight, the drop-weight impact test was performed on steel fiber-reinforced coal gangue concrete beams with a span of 300 mm; the damage pattern, impact reaction force-time, displacement-time relationships, and energy absorbed by steel fiber-reinforced coal gangue concrete beams were studied. The test shows that, compared with natural aggregate, CGA reduces concrete's static mechanical properties and impact resistance, and adding SF improves the static mechanical properties and impact resistance of coal gangue concrete. As the CGA replacement rate increased from 0 % to 50 % and 100 %, the reaction force of impact of the specimens decreased by 2.54 %− 6.06 % and 3.69 %− 12.33 %. The SF volume content was increased from 0 % to 0.75 % and 1.5 %, and the reaction force of impact of the specimens was increased by 23.05 %− 32.34 % and 72.27 %− 81.84 %, respectively. The impact resistance of steel fiber-reinforced concrete beams under impact loading was investigated numerically using a nonlinear explicit finite element model in LS-DYNA. The Finite Element results were validated with experimental results. Based on the validated finite element model, a parametric study was carried out to investigate the effects of coal gangue replacement rate, steel fiber volume content, and drop height of the drop weight on the behavior of the beams. This study might provide a basis for the future engineering project applications of steel fiber-reinforced coal gangue concrete under impact conditions. • New sustainable coal steel fibers reinforced gangue aggregates (CGA) concrete was investigated. • Impact resistance of this new type of concrete was studied. • Numerical modelling was made to this new type of structure. • Parametric analysis of SFCGC beams was carried out [ABSTRACT FROM AUTHOR]

A series of numerical simulations were completed to investigate the behavior of intact, fire-damaged, and Carbon Fiber-Reinforced Polymers (CFRP) retrofitted reinforced concrete (RC) bridge columns of varying sizes subjected to vehicle collisions. Three-dimensional finite element models of isolated RC columns and their foundation systems surrounded by soil volumes were developed using LS-DYNA. A comprehensive parametric study was carried out to investigate the effects of nine demand and design parameters on the performance of bridge columns. Studied parameters included: column diameter, column height, unconfined compressive strength, steel reinforcement ratio, fire duration, CFRP wrap thickness, wrapping configuration, vehicle's mass, and vehicle's speed. For each studied scenario, Peak Twenty-five Milli-second Moving Average (PTMSA) was employed to estimate the Equivalent Static Force (ESF) corresponding to each vehicle collision scenario. Resulting ESF s were then utilized to assess effectiveness of the current ESF approach available in the American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO-LRFD) Bridge Design Specification for analyzing and helping design bridge columns under vehicle collision. Multivariate nonlinear regression analyses were used to derive an empirically based, simplified equation to predict the ESF that corresponds to a vehicle collision. Rather than constant design force, this equation established a correlation between ESF and kinetic energy, column axial capacity, and column height. Results indicated that the proposed equation is reliable and can accurately predict ESF s over a diverse range of collision scenarios that included intact, fire damaged, and CFRP retrofitted columns. To facilitate realistic implementation of the derived equation, an ESF assessment framework was also devised. • Performance assessment and insights on intact, fire-damaged, and CFRP retrofitted bridge pier columns under vehicle impact. • Developed 3D finite element models of isolated bridge column, foundation system, and surrounding soil domain using LS-DYNA. • Conducted a comprehensive parametric study including nine demand and design variables. • Derived an empirically based, simplified equation that predicts ESF over a wide range of vehicle collision scenarios. • Proposed an assessment framework to facilitate the implementation of the proposed equation. [ABSTRACT FROM AUTHOR]

Highlights • An FE model for predicting the flexural behaviour of UHPC was investigated. • The numerical approach was validated with 21 UHPC specimens. • The FE model accurately traces the flexural performance of the tested specimens. • The simulated and experimental ultimate load and deflection agree well. Abstract This paper presents a finite element (FE) modelling to predict the behaviour of ultra-high performance concrete (UHPC) members under static flexural loading. A plasticity-based constitutive model for concrete and an implicit solver in LS-DYNA were adopted in the numerical simulation. Experimental data for 21 UHPC specimens tested in the present study and in previous works were used to calibrate and validate the proposed FE model and modelling technique. The simulation was able to accurately predict the experimentally obtained ultimate strength, stiffness, and hardening and softening behaviours of the specimens. This demonstrates the effectiveness and adequacy of the developed FE model and modelling technique. [ABSTRACT FROM AUTHOR]

• Full-scale blast testing of RC structure with successive explosive charges. • Maximum slab deflection of 42 mm after 3 blast test up to 20 kg TNT. • Crater generated in the RC slab about 66 cm diameter with 20 kg TNT at 0.5 m. • RC structures following EC2 can withstand explosive charges up to 20 kg TNT at 0.5 m. Three full scale tests have been carried out on the same structure to determine the effect produced by several blast loadings detonated at different times. The structure is a two-span 7.00 × 14.00 m2 RC frame subjected to explosives load from 10 to 20 kg TNT equivalent at distances varying from 0.5 m to 1.5 m. The tests were monitored using pressures gauges, accelerometers, high-speed camera and a 3D topography scanner for measurement of permanent deflections. The test results show the robustness of the slab, with only minor cracking damage in the first two loading scenarios and only local damage in the third scenario, where the equivalent load of 20 kg TNT is placed only 50 cm from the slab surface. The third test produced maximum deflections of about 4 cm and a local punching failure measuring 66 cm in diameter on the upper face and 82 cm in diameter on the lower face. The simulation of the building was carried out with the LS-DYNA software with a Lagrangian formulation for the walls, using the Load Blast Enhanced (based on CONWEP) module. Permanent defections and damage has been evaluated and has been compared with numerical modelling. [ABSTRACT FROM AUTHOR]

Highlights • Cross-platform implementation of advanced models of elastomeric seismic isolation bearings in OpenSees, ABAQUS, and LS-DYNA. • Capabilities and limitations of user elements in three software platforms. • Implementation of a framework for verification and validation of numerical models for seismic isolators. • Discussion on the limitation of the isolator models and error quantification. • Estimation of the parameters of the mathematical model of elastomeric bearings in tension. Abstract Stable inelastic response of seismic isolation bearings is key to the successful performance of base isolated nuclear structures, buildings and bridges. Since full-scale isolated nuclear structures (and buildings) cannot be tested for extreme earthquakes on simulators because their payload capacities are orders of magnitude smaller than weights of structures, confirmation of adequate performance must be provided by analysis of numerical models and testing of individual bearings. As the consequences of isolator failure are high, for example, core damage in a nuclear power plant and collapse for a building, the numerical models of the key nonlinear components, namely, the isolators, must be verified and validated (V + V). Herein, advanced models of elastomeric seismic isolation bearings are implemented as user elements in the open-source code OpenSees, and the commercial codes ABAQUS and LS-DYNA. These advanced models are verified and validated following ASME best practice to predict response under extreme loadings. Sources of error in the computational models are quantified, and where possible, eliminated. Those isolator characteristics crucial to robust estimates of performance are identified. Experiments are performed to obtain data for validation. The isolator models are validated using data from experiments and values of model parameters are recommended. [ABSTRACT FROM AUTHOR]

A finite element model is developed in LS-DYNA to simulate the in-plane cyclic behavior of lightly reinforced, low-aspect ratio reinforced concrete (RC) shear walls. Data from tests of 22 low-aspect ratio RC shear walls in three laboratories are used to validate the numerical model. The design variables in the testing programs included aspect ratio, day-of-test concrete compressive strength, vertical and horizontal web reinforcement ratio, reinforcement ratio in boundary elements, and yield and ultimate strengths of reinforcement, and these are addressed in the numerical model. The finite element predictions and test results, including the force–displacement relationships and damage to the RC shear walls, are presented and contrasted. Numerical methods are proposed to model the effect of early stage cracking on the initial stiffness of RC walls and to capture post-peak strength degradation. The numerical simulations are in good agreement with the measured responses. The validated LS-DYNA model is used in a parametric study to investigate the effects of wall aspect ratio, reinforcement ratios in web and boundary elements, and compressive axial load on the monotonic response of RC walls. The accuracy of four equations used to predict the peak shear strength of low-aspect ratio walls is assessed using results of the numerical analyses. [ABSTRACT FROM AUTHOR]

• Paper describes a methodology that was successfully applied for the development of a temporary road traffic steel barrier in compliance with T1/W1 level according to EN 1317; • A simplified theoretical analysis of 178 barrier, laboratory test of three types of barrier connectors (for two types of barrier), explicit FEM modeling of four chosen barrier, and a full-scale crash test for final barrier are presented; • The stiffness of barrier connector was established based by laboratory barrier test (the FEM model was validated based on laboratory tests); • The chosen final barrier alternative passed the crash test for T1/W1 (TB21) containment level, performed by certified laboratory [35] , which proves that the presented procedure could be used successfully for traffic barrier development. Over a million people die in road crashes and tens of millions result injured or disabled each year, globally. Hence, there is a constant concern for improving the safety of the roads to protect road users, and those at the most risk, the road workers. Construction, maintenance, and utility work are constantly needed to ensure safety and functionality of roads and highways. Temporary road traffic barriers are used to separate passing traffic from the workspace and protect the workspace from an errant vehicle intrusion. Steel barriers are light, and their major advantage is rapid installation. These barriers are not anchored to the ground, and their behavior relies on the base-pavement friction, mass inertia, and stiffness of the system. The paper describes a methodology that was successfully applied for the development of a temporary road traffic steel barrier in compliance with the European specification EN 1317. The study included a simplified theoretical analysis of 178 barriers, static laboratory tests of three types of barrier connectors, development of explicit finite element models (EFEMs) of four selected barrier designs, and a full-scale crash test of the final barrier design. It is shown that static laboratory tests of complex connector systems can help to improve the design process and reduce the cost. The analysis and use of EFEMs was enough so that just a single full-scale crash test was sufficient for certification of the barrier design for use in Europe. The final barrier is compliant with the EN 1317–2 requirements for T1/W1 (TB21) containment level, which was confirmed by a full-scale crash test. [ABSTRACT FROM AUTHOR]

Concerns have risen from building responses and resulting fatalities in some recent infamous terrorist attacks. The collapse of the Alfred P. Murrah Building, for instance, revealed that failure of load-bearing members could lead to extensive building failure. It has become imperative to investigate the blast resistance offered by loading-bearing structural members designed for gravity loads and other load types such as earthquakes. Reinforced concrete (RC) columns not forming part of the seismic force resisting system were detailed according to CSA A23.3-04 – Design of Concrete Structures. Using a high-fidelity physics-based finite element code, LS-DYNA, a numerical study was undertaken to investigate the effects of transverse reinforcement spacing on the blast resistance of RC columns. The study shows that the effect of transverse reinforcement spacing and axial loading significantly affects RC column behaviour under blast loading at low scaled distances. At higher scaled distances, however, the effects were insignificant. [ABSTRACT FROM AUTHOR]

Both the peak dynamic force (PDF) and the equivalent static force (ESF) of a vehicle collision with reinforced concrete bridge columns were examined as part of an extensive finite element (FE) analyses study. An extensive parametric study of 13 parameters, including the concrete material model, the unconfined concrete compressive strength f c ′ , the material strain rate, the percentage of longitudinal reinforcement, the hoop reinforcement, the column span-to-depth ratio, the column diameter, the top boundary conditions, the axial load level, the vehicle’s velocity, the vehicle’s mass, the roadside distance between errant vehicle and unshielded bridge column, and the soil depth above the top of the column footing was conducted. Three approaches were used to investigate the ESF. The ESF in the first (stiffness-based) approach was defined as the static force producing the same maximum displacement that is produced by a vehicle collision at the point of impact. The ESF examined in the second approach was calculated according to the Eurocode. The ESF studied in the third approach was defined as the Peak of the Twenty-five Milli Second moving Average (PTMSA). The different ESFs were compared to the ESF in the American Association of State Highway and Transportation Officials-Load and Resistance Factor Design (AASHTO-LRFD; 2670 kN [600 kips]). In general, the ESF calculated according to the Eurocode presented the lower bound while those from the stiffness-based approach presented the upper bound. Furthermore, the recommended ESF of the AASHTO-LRFD was found to be non-conservative for heavy and/or high speed vehicle impacts; it was found to be too conservative for light and/or slow vehicle impacts. Hence, rather than a constant design impact force, a variable design impact force should be used. An equation was developed to calculate a design impact force, which is the function in the vehicle’s mass and velocity. A simplified equation based on the Eurocode equation of the ESF was proposed. These equations, however, do not require cumbersome FE analyses. [ABSTRACT FROM AUTHOR]

The air blast that is generated by the explosion of bombs or fuel tankers on or adjacent to a bridge can cause severe structural damage, and may result in partial or full collapse of the bridge. The dynamic response and structural performance of buildings under blast has been the subject of several studies, with considerably less attention being paid to the assessment of bridges under extreme blast loading scenarios. To reduce the computational expense of conducting blast analyses on large or complex bridges, the numerical sub-structuring technique is used in current practice. However, the simplifying assumptions adopted in these sub-structuring methods can lead to erroneous results. Accordingly, this study attempts to simulate numerically the dynamic response of an entire cable-stayed bridge subjected to blast loading using the LS-DYNA explicit finite element code. Based on best practice available in the literature, the blast load estimation, material modelling and detailed numerical simulation are carried out and the response of a cable-stayed steel bridge (designed according to minimum requirements of the Australian Bridge Standard) under blast loads ranging from a small to large detonation at different positions above the deck and near pylon are obtained. Furthermore, the potential effects of blast loads on different structural components with a focus on the cross-sectional geometry of the pylons are investigated. [ABSTRACT FROM AUTHOR]

This paper presents results of numerical studies on the in-plane monotonic response of steel-plate concrete (SC) composite shear wall piers. Results of finite element analysis of 98 SC wall piers are used to investigate the effects of wall aspect ratio, reinforcement ratio, slenderness ratio, axial load, yield strength of the steel faceplates, and uniaxial compressive strength of concrete on in-plane response, and to formulate (a) predictive equations to establish the trilinear lateral force versus lateral displacement response of SC wall piers up to peak strength, sufficient for seismic analysis of structures including SC wall piers and (b) a mechanics-based design equation for peak flexural strength, which addresses the interaction of co-existing shear and axial force. Design of Experiments is used to select the 98 piers. The baseline finite element model was formally validated using data from reversed cyclic, inelastic in-plane tests of four large-scale SC wall piers. [ABSTRACT FROM AUTHOR]

• 6 mm thick polyurea layers offer an adequate improvement in retrofitting CMU walls. • The polyurea systems can deflect and sustain debris during a blast event. • Polyurea coatings do not increase the out-of-plane resistance of the wall. A blast event may result in structural damage, generating high velocity fragments that usually come from masonry walls. To reduce the extent of damage from an explosion, one solution is to improve the strength of the structures. This can be achieved by retrofitting. In the field of safety against blast loading, experimental tests are of great value in assessing and understanding the phenomenon and its effects on structures. However, experiments in a blast environment are difficult and expensive to conduct. For that reason, numerical modelling is commonly used as an alternative to experimental testing. In this study, four concrete masonry walls were tested in two different blast trials carried out at full scale; one wall was unreinforced, and the other three were retrofitted with different polyurea coating systems. Additionally, a numerical model using a finite element code was applied to reproduce the experimental tests. The geometric model was created using a detailed micro-modelling approach. To calibrate the simulation, the results between the field test and the numerical model were compared using quantitative and qualitative data. A parametric study was carried out to explore the rupture limits of the polyurea layer. The polyurea coatings that were tested proved to be a good retrofit option for non-load bearing concrete masonry walls. According to the present work, it was found that a thickness of 6 mm provided a satisfactory improvement in retrofitting concrete masonry walls, although a 10-mm thick layer would considerably increase the rupture limit of the polyurea. The numerical modelling method used appears to be an acceptable approach for reproducing blasting tests. [ABSTRACT FROM AUTHOR]

Over the past two decades, blast loads have been recognised as one of the extreme loading events that must be considered in the design of important structures such as cable-stayed bridges. However, design provisions for blast-resistant bridges are very limited and mostly empirical owing to an inadequate understanding of the local and global dynamic response of the bridge components (piers, deck and cables) subjected to blast loading scenarios. Accordingly, this study develops detailed finite element models of a steel cable-stayed bridge and it is analysed using an explicit solver. Three different explosive sizes, i.e. small (01W), medium (04W) and large (10W), are considered (W being the TNT equivalent explosive weight index) and placed at different locations above the deck level to determine the influence of the size and location of the blast loads on the global and local response of the bridge components. In particular, the results of the computer simulations are employed to characterise the type and extent of damage on the pylon and deck, and additionally to investigate the potential cable loss scenarios associated with a loss of anchorage. Furthermore, the results of the finite element simulations are used to assess the potential progressive collapse response of a cable stayed bridge subject to various blast loading scenarios. [ABSTRACT FROM AUTHOR]

The objective of the present work is to investigate the dynamic structural response of perforated plates subjected to water impact load. A fully coupled ALE/FEM method, is used to simulate the fluid–structure coupling problem. The deformations of the plate and of the water are coupled through the hydrodynamic pressure subjected by the water on the plate, and the velocities of the structural particles affecting the deformation of the water. Considering plates with various numbers of openings resulting in a different degree of opening intensity, the structural deformations around the plate are analysed. The effects of the number, degree and location of the openings on the maximum distortion and recovering rate of the plate are analysed. The predictions of the plates’ distortions at two typical time moments during the impact loading are estimated by the proposed mathematical equations. [ABSTRACT FROM AUTHOR]

• Simulation procedure to predict impact force excitation generated by an ISO tapping machine on wooden floors. • Computation via finite element method and explicit time integration to consider the non-linear interaction between the hammers and the floor. • Model validation showed good agreement with experimental results on a cross-laminated timber slab. • Sensitivity analysis revealed that local properties of the slab were the most important to the impact force pulse. Application of simulation tools to compute impact sound insulation properties of wooden floors has raised interests in recent decades. To achieve accurate results from the prediction models, information from force excitation generated by impact sound sources is required. The purpose of our study was to present a validated procedure to determine the non-linear impact force excitation generated by an ISO tapping machine. The method comprised use of finite element method (FEM) and explicit time integration to compute impact force pulse generated by a hammer of the tapping machine. With a post-processing procedure, the force pulses can be converted to present point forces describing the continuous operation of the tapping machine on the floor. To demonstrate the applicability of the method, the finite element model was applied to imitate an experimental situation on a cross-laminated timber (CLT) slab. The model validation showed that the computational model closely predicts the force pulse generated on the CLT slab. Findings from a sensitivity analysis revealed that local properties of the slab were the most important to the simulated impact force pulse. The findings of the analysis are helpful for those developing simulation tools to compute the impact force generated by the tapping machine on wooden floors. [ABSTRACT FROM AUTHOR]

Confinement of both existing and newly constructed reinforced concrete (RC) columns by fibre reinforced polymer (FRP) has been commonly used in recent decades. This is because of its ability to enhance the shear resistance and the ductility of the RC columns, which are the main parameters that govern the behaviour of RC columns under lateral loading. This paper presents a finite element (FE) model that was developed using the LS-DYNA program aimed at modelling the plastic hinge length ( l p ) for FRP-confined RC columns. A FE parametric study was conducted to investigate the effect of FRP-confinement on l p . Empirical models were proposed to predict l p and the ultimate drift ratio ( δ u ) for FRP-confined RC columns and the results were compared with similar previous models. The proposed FE model was able to predict the plastic hinge region and l p value which can provide a simple way for designers to investigate the behaviour of FRP-confined columns during the design process. The proposed δ u model reduced the average of errors (A) and standard deviation (SD) by 15.1%, 3.9%, respectively, compared to the best predictions by previous models. [ABSTRACT FROM AUTHOR]

A finite element model is developed in LS-DYNA to simulate the nonlinear cyclic response of flexure-critical steel-plate concrete (SC) composite shear walls. The developed finite element model is validated using data from tests of four large-scale SC wall piers with an aspect ratio (height-to-length) of 1.0. Each SC wall was constructed with steel faceplates, infill concrete, steel studs and tie rods, and a steel baseplate that was post-tensioned to a reinforced concrete foundation. Steel studs tied the faceplates to the infill concrete and the infill concrete to the baseplate. Damage to the SC walls included cracking and crushing of the infill concrete and yielding, outward buckling and tearing of the steel faceplates. The finite element predictions include global force–displacement responses, equivalent viscous damping ratio, damage to the steel faceplates and infill concrete, strain and stress distributions in the steel faceplates, and estimates of the contribution of the steel faceplates and infill concrete to the lateral resistance of the walls. The DYNA-predicted responses are in good agreement with the measured responses. The impacts of interface friction between the steel faceplates and the infill concrete, and of the distribution of shear studs on the baseplate, to the global response of the SC walls are investigated using the validated DYNA model. [ABSTRACT FROM AUTHOR]

• Impactor geometry is important parameters affected the behavior of RC members. • Experimental/ numerical studies about impactor geometry are limited in literature. • Three flat-surface and hemispherical hammers with different surface areas are used. One of the important parameters that affect the behavior of the reinforced concrete (RC) members under impact loading is the impactor geometry used for applying impact loading. It is known that changes in the impactor geometry have significant effects on energy transfer to the structural system, deformation distribution, and damage on structural members caused by impact loading. However, there is no encounter with a study with a detailed and comprehensive conclusion on this topic during the literature review. The lack of this kind of conclusion leads to an experimental study with different impactor geometries applying impact loading on RC slabs. These experiments examine the effects of impactor geometry on acceleration-time, displacement–time, impact loading-time, and maximum strain–time behaviors. In addition to those, effects on damage distribution and impact loading behaviors are examined. This study uses three flat-surfaced hammers with different surface areas and a hemispherical hammer. Impact loading is applied at two different magnitudes on specimens. Ls-Dyna software is also used to do numerical analysis for the members. Outputs of the analysis are compared with the experimental results to evaluate the modeling of effects of change in impactor geometry. When the results obtained as a result of the experimental study were examined, it was seen that the change in the geometry of the impactor to which the impact loading was applied significantly changed the behavior of the slabs under the impact loading. The increase in the impactor contact area caused an increase in the impact loading applied to the specimens, and the acceleration, displacement, residual displacement, and strain values measured from the specimens all increased. [ABSTRACT FROM AUTHOR]

Concrete dilation is one of the main parameters that controls the stress–strain behaviour of confined concrete. Several analytical studies have been carried out to predict the stress–strain behaviour of concrete encased in fibre-reinforced polymer (FRP), which is crucial for structural design. However, none of these studies have provided a simple formula to determine the dilation parameter that is always required in the finite element (FE) material modelling of concrete. This paper presents a simple empirical model predicting the confined concrete dilation parameter within the theoretical framework of a Karagozian and Case type concrete plasticity model. A set of 105 FRP-confined specimens with different unconfined concrete strengths ( f ′ c ) and confinement moduli ( E 1 ) was analysed using the LS-DYNA program. The model predictions of the confined ultimate strength ( f ′ cc ), confined ultimate axial strain ( ℰ cc ) and confined ultimate hoop strain ( ℰ h ) were compared with the corresponding experimental database results for each specimen. In addition, the model axial and hoop stress–strain curves of each specimen were developed and compared with the corresponding experimental ones. The proposed model was able to predict stress–strain curves of the test specimens quite well .The proposed model was able to predict f ′ cc with mean errors ( M ) and standard deviations ( SD ) of 2.6% and 10.7%, respectively. Similarly, the model predicted ℰ cc with M and SD values of 0.3% and 29.0%, respectively. Finally, the model was less successful in predicting ℰ h with M and SD values of 13.7% and 26.3%, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] We simulate the impact collision of truck and curved railing by FE model using LS-DYNA software. [•] Absorbed energy and displacement of railing will increase with rising of railing curvature. [•] Absorbed energy and displacement of railing will increase with rising of impact angle. [Copyright &y& Elsevier]

• The contact explosion size effect of reinforced concrete slab is revealed with experiments. • The impact echo device was used to test concrete damage under direct contact explosion. • Suggest choosing a scale ratio of more than 1/4 to reduce size effect under contact explosion. The static size effect of concrete is well known; however, investigations on the size effect of reinforced concrete slabs under direct contact explosion remain scarce. It is of great importance to understand the size effect so that the scale model test results can be applied to real damage of full-scale structures subjected to explosion. This paper presents an experimental investigation consisting of eleven direct contact explosion tests carried out to investigate the size effect phenomenon in reinforced concrete slabs. The results indicate that the explosion size effect is clearly observed; that is, the specimens of smaller sizes had less bottom spalling damage even if the upper crater size was approximately the same proportion. Furthermore, the damaged area tended to decrease as the steel ratio increased. Non-destructive testing can detect the damage location and depth of reinforced concrete slabs after explosion by imaging. Finally, finite element model based on LS-DYNA is developed and validated by experimental results for the numerical investigation of the reinforced concrete slab under direct contact explosion. [ABSTRACT FROM AUTHOR]

• Develop P–I models for FRP retrofitted RC columns to predict and assessment of blast damages. • Proposed a new method to determine the damage index to identify the capacity degradation of the RC columns when exposed to extreme loads. • Applied LBE function to simulate blast loads in RC columns retrofitted with FRP composite. • Validation of numerical simulation of FRP strengthened RC column compare to experimental blast field test. The efficiency of fibre reinforced polymer (FRP) in strengthening the concrete structure against blast loads is investigated for RC columns exposed to blast loads. It should be mentioned that no systematic investigations derived pressure and impulse (P-I) models for FRP retrofitting RC columns in the literature. Thus, the primary goal of this project is to construct a finite element model that will offer data for the development of a P-I diagram that can be utilized to mitigate blast threats and predict damage in RC columns retrofitted with FRP. Another aspect of the present work is to propose a new technique to determine the damage index to identify the capacity degradation of the RC columns when exposed to extreme loads in the current research various strengthening schemes are quantitatively tested against blast loads by doing LS-DYNA software. Numerical simulation of blast load is implemented by using Load-Blast-Enhanced (LBE) technique. The models are validated through experimental work to assess the correctness of model simulations in order to illustrate the models behavior. The structural behavior of un-strengthened RC columns was compared to the structural behavior of various columns retrofitted with varying FRP wrap thickness, strength, and arrangement. The simulations revealed that strengthening columns with FRP is a viable strategy to improve their explosion resistance capability, and that retrofit procedures are useful in minimizing the building's hazard. Engineers can utilize the P–I curves obtained to assess the damage levels of new columns and to estimate the damage levels of existing columns subjected to different extreme load scenarios. [ABSTRACT FROM AUTHOR]

• Study the hail impact with the intermediate-velocity range (10 – 50 m/s). • Investigate the effectiveness of simulation methods and material models in LS-DYNA®. • Arbitrary Lagrangian-Eulerian method combined with MAT155 has the best performance. Hail impact on structures such as building envelopes and vehicles can cause huge economic loss every year. Numerical simulation of the hail impact process is crucial for the mitigation strategy development. However, very few research works are focused on the hail impact simulation with impact velocity that falls into the intermediate-velocity range (10 – 50 m/s), to which the static structure could be exposed during a hailstorm. This study is to investigate the effectiveness of three simulation methods (Lagrangian method, Arbitrary Lagrangian-Eulerian method (ALE) and Smooth Particle Hydrodynamics method (SPH)) and three built-in material models from LS-DYNA® (MAT10, MAT13 and MAT155) on modeling hail during an intermediate-velocity impact process. The performance of each combination of simulation method and material model is evaluated by comparing the contact force results with the documented experimental results. Statistical analysis was conducted to check the accuracy of the simulation model. It was shown that ALE method combined with MAT155 has the best performance on contact force profile prediction. The findings were further validated by case studies. Outcomes from this study provide insights on the effect of various failure material treatment methods of the solvers and the material models on the hail failure mode and their reflection on the contact force, which can assist the selection of simulation method and material model for hail modeling for an intermediate-velocity impact. [ABSTRACT FROM AUTHOR]

• Full-scale blast testing of RC slabs with different scaled distances. • FE-LBE and FE-SPH slabs present reasonable acceleration values with CSCM, MAT72-R3 and JHC. • FE-LBE model with CSCM is able to reproduce the slab perforation in near field blasts. • MAT72-R3 and JHC concrete models do not work as well for tests with 0.83 m/kg1/3. • FE-SPH model reproduces the damage pattern with reasonable errors in damage area. This paper investigates the response of three reinforced concrete slabs subjected to a dynamic (explosive) load at close range, through full-scale testing and its subsequent simulation with numerical models. The first slab was subjected to 1.74 kg of TNT equivalent at one-meter distance and instrumented with pressure and acceleration sensors. In the second slab, the load was increased to 13.05 kg of TNT equivalent while maintaining the distance; finally, the load from the second case was maintained but the distance was decreased to half a meter. The results of the three slabs were compared with respect to the concrete damage surfaces. A well-known Finite Element (FE) model with LOAD BLAST ENHANCED (LBE) tool has been used to numerically describe the slab and the explosive charge, respectively. Three different concrete material models have been used for the description of the first slab with the FE-LBE model. Numerical models adopting coupled Finite Element (FE) and Smoothed Particle Hydrodynamics (SPH) (for the charge definition) have also been developed for the same slab, including the three concrete material models and two alternatives to describe the explosive mass. After comparing the damage evolution with different material models for the concrete in the first test, the remaining tests have been simulated with the concrete model that presented the best results. In the FE-SPH models the load has been simulated with three geometries (cylinder, cube and bag) to account for the uncertainty in geometry of the explosive charge. The cylindrical charge is the best replicating the detonation pressure, the cubic charge is the best reproducing the surface damage and the bag shaped gets the best results regarding the acceleration. FE-SPH models are able to reproduce the shape of the surface damage slightly better than the classic FE-LBE, an important finding when the explosive charges are not spherical. On the contrary, the ratio of surface damage is closer to that obtained in the tests for the FE-LBE models compared to the FE-SPH models. [ABSTRACT FROM AUTHOR]