Lateral Impact Research Articles

Performance of concrete filled steel tubular (CFST) members with circumferential gap under lateral impact

To investigate the influence of circumferential gap on the impact-resistance capacity of CFST columns, 12 CFST specimens were tested under constant axial load and lateral impact loading at mid-span. The test parameters included gap ratio, impact velocity, and slenderness ratio. The failure mode, impact force versus time curves, and deflection versus time curves of CFST specimens with circumferential gap were experimentally investigated and compared with those of the reference samples without any gap. Based on the test results, the failure mode, impact force history, deflection response, and energy dissipation of the specimens were experimentally investigated, and the influence of the above parameters on the impact-resistance of CFST specimens was analyzed. To further explore the force transfer mechanism of CFST with gap under lateral impact, a finite element analysis (FEA) model was established, and the influence of the gap on the contact stress, internal force transfer mechanism, and dynamic flexural capacity of CFST specimens was analyzed. Lastly, a simplified formula for predicting the dynamic flexural capacity of CFST considering the influence of circumferential gap was proposed, which could provide a reference for practical engineering applications.

Experimental and Numerical Flexural–Torsional Performance of Thin-Walled Open-Ended Steel Vertical Pile Foundations Subjected to Lateral Loads

This research investigates the effects of torsional moments on the mechanical behavior of thin-walled open-ended vertical pile foundations subjected to lateral wind loads. The aim of this research is to determine and quantify the errors using traditional design methods and provide more effective alternatives. The warping and torsion effect generated over the piles due to the resultant lateral load impact outside the shear center is analyzed in field tests. Complementarily, a two-dimensional finite element model based on the simple bending stress–strain state, as well as a three-dimensional finite element model considering torsional effects, were implemented and their results analyzed. Finally, a comparative analysis between the in-field lateral loading tests and the finite element model approaches was established by comparing load–displacement curves and using a non-linear Wrinkle model of the soil. Additionally, correlations between the experimental and finite element model errors for the cross-sections pile with a different torsional constant and torsional susceptibility index are shown. From the results, it has been ascertained that the slender thin-walled open-ended pile foundations are particularly sensitive to small load deviations from their center of gravity; this leads to the fact that the slenderer the load and the greater its eccentricity, the more it affects the torsion and warping of the pile. Calculation methodologies usually consider a simple in-plane bending behavior, which leads to errors between 44 and 58% in comparison with the experimental results obtained.

Experimental and numerical investigation on the lateral impact responses of CFST members after exposure to fire

The impact load acting on structure can cause a completely different structural response from the static load, and structure may be subjected to both impact and fire in extreme events, leading to severe structural damage or collapse. This paper reports the lateral impact responses of concrete-filled steel tubular (CFST) members after fire. Nine CFST specimens with different parameters, i.e., the fire duration time, impact heights, and boundary conditions, were tested using an electric furnace and a drop hammer impact system. The failure modes, impact force, midspan deflection, and energy absorption were investigated and compared. Results reveal that post-fire CFST members exhibit global bending failure under lateral impact, and increasing the fire duration time reduces the impact resistance of CFST members, with lower peak and plateau impact forces but larger deflection. The finite element (FE) model of post-fire CFST members under lateral impact was developed and calibrated against the test results to further analyze the impact responses. In addition, simplified methods were proposed for the evaluation of dynamic flexural capacity, plateau impact force and maximum deflection of CFST members subjected to lateral impact.

Dynamic response of concrete-filled square steel tubular columns under lateral impact load at flat or corner zone

The dynamic response of columns under lateral impact is of great significance for guiding structural design under accidental loads. The present study aims to investigate the effect of different impact directions on the dynamic response of square concrete-filled steel tubular (CFST) columns by conducting drop hammer tests at flat or corner zones. The main experimental parameters included hammer mass, drop height, indenter radius, built-in steel bars, shear span ratio, width-thickness ratio, and column sizes. The experimental results showed that the impact zone has a significant effect on the dynamic response of CFST specimens. Under higher impact energies, specimens impacted at corner zones were more likely to fracture on the tensile side of the steel tube than specimens impacted at flat zones. And the specimens impacted at the corner zone were more sensitive to the change of indenter radius. Smaller shear span ratios, built-in steel bar, and larger column sizes improved the impact resistance of tested specimens. The 3D finite element models were developed and analyzed by ABAQUS/Explicit to explore dynamic behavior further.

The Influence of Different Dynamic Material Constitutive Models on the Impact Performance of Circular CFST Columns

At present, there is a lack of research on the influence of different dynamic constitutive models of steel and concrete on the dynamic mechanical properties of concrete-filled steel tubular (CFST) columns under lateral impact. In this paper, A comprehensive numerical study on the effects of different dynamic constitutive models of steel and concrete on the lateral impact response of CFST columns was conducted. The dynamic constitutive models of steel and concrete with different strengths were divided into four categories, namely, normal-strength steel, high-strength steel, normal-strength concrete and high-strength concrete. The established finite element model of CFST columns considering the progressive damage degradation of steel as well as the compressive and tensile damage factors of concrete was verified against published experimental data. Based on the verified FE model, the effects of different dynamic constitutive models of steel and concrete on the impact response of circular CFST columns were analyzed. The analyzed results show that the different dynamic constitutive models of steel have different effects on the impact force and mid-span time-history deflection curves of CFST columns. The analysis result, ignoring the effect of concrete strain rate, is in good agreement with the CEB-FIP model considering the effect of steel strain rate. This is because the largest proportion of the impact energy of CFST members is mainly assimilated by the outer steel tube.

Ligaments Laxity and Elongation at Injuryin Flexed knees during Lateral Impact Conditions.

The knee is one of the regions of interest for pedestrian safety assessment. Past testing to study knee ligament injuries for pedestrian impact only included knees in full extension and mostly focused on global responses. As the knee flexion angle and the initial ligament laxity may affect the elongation at which ligaments fail, the objectives of this study were (1) to design an experimental protocol to assess the laxity of knee ligaments before measuring their elongation at failure, (2) to apply it in paired knee tests at two flexion angles (10 and 45 degrees). The laxity tests combined strain gauges to measure bone strains near insertions that would result from ligament forces and a custom machine to exercise the knee in all directions. Failure was assessed using a four-point bending setup with additional degrees of freedom on the axial rotation and displacement of the femur. A template was designed to ensure that the two setups used the exact same starting position. The protocol was applied to six pairs of knees which were tested until the failure of all ligaments. In the laxity tests, a higher compliance of the knee was observed at 45 degrees compared to 10 degrees. Minimum lengths associated with the beginning of bone loading were also successfully identified for the collateral ligaments, but the process was less successful for the cruciate ligaments. The failure tests suggested increased elongation and length at failure for the ligaments and their bundles at 45°. This could be consistent with the higher compliance in static test, but the minimum lengths identified on the collaterals did not explain this difference during failure. The results highlight the possible relationship between position, laxity and elongation at failure in a lateral loading and provide a dataset including 3D coordinates of insertions to continue the investigation using a modelling approach. Perspectives are also outlined to improve upon the laxity determination protocol.

Optimization of crashworthiness of CFRP thin-walled beams filled with aluminium honeycomb based on surrogate model

The CFRP thin-walled beam filled with aluminum honeycomb is a new design form in the crashworthiness design of automobile energy-absorbing component. It not only meets the requirements of strength, rigidity and lightweight under the normal load, but also ensures absorption of crash energy in a stable failure mode when a crash occurs. In this paper, under two typical conditions of axial impact and lateral impact, structural sample points are established by orthogonal experiment; a highly feasible surrogate model is constructed based on the radial basis function; the initial load peak Fmax and specific energy absorption (SEA) are taken as the main criteria to evaluate the energy absorption performance of the structure; the multi-objective genetic optimization algorithm NSGA-II is used to optimize the energy absorption design of CFRP thin-wall beams filled with aluminum honeycomb. The structure and material parameters of the minibus frame are optimized according to the crash condition to improve the energy absorption performance of the minibus in frontal and side crashes, and on this basis, an effective method to improve the crashworthiness of minibuses is explored.

Failure Modes Behavior of Different Strengthening Types of RC Slabs Subjected to Low-Velocity Impact Loading: A Review

Concrete is brittle; hence, it is incredibly likely that concrete buildings may fail in both local and global ways under dynamic and impulsive stresses. An extensive review investigation was carried out to examine reinforced concrete (RC) slab behavior under low-velocity impact loading. Significant past research studies that dealt with experimental and numerical simulations and analytical modeling of the RC slabs under impact loading have been presented in this work. As a result, numerous attempts to define failure behavior and to assess concrete structures’ vulnerability to lateral impact loads have been made in the literature. Based on analytical, numerical, and experimental studies carried out in previous research, this article thoroughly reviewed the current state of the art regarding the responses and failure behaviors of various types of concrete structures and members subjected to low-velocity impact loading. The effects of different structural and load-related factors were examined regarding the impact strength and failure behavior of reinforced concrete slabs reinforced with various types of strengthening procedures and exposed to low-velocity impact loads. The reviews suggested that advanced composite materials, shear reinforcement, and hybrid techniques are promising for effectively strengthening concrete structures.

Axial Compression Performance of Reinforced Concrete Columns after Lateral Impact Load

Axial compression performance and bearing capacity of reinforced concrete column is crucial to concrete structure. Lateral Impact load could pose severe danger to the security and service life of reinforced concrete column. Impact dynamic response, axial compression performance and residual bearing capacity of reinforced concrete columns after lateral impact load were investigated in this paper. Investigation results indicated that with the increase of impact energy, residual displacement and crack width on column increased, impact damage on column exacerbated. It was proved that impact resistance performance of reinforced concrete column could be enhanced by preload axial force. Residual bearing capacity of reinforced concrete column degenerated obviously after subjected to lateral impact load. And RC column would be under elastic stage when impact energy was low. According to analysis results on the correlation between residual displacement and residual bearing capacity, prediction model on residual bearing capacity of reinforced concrete column after lateral impact load was proposed.

Experimental and numerical investigation on the deformation behaviors of large diameter steel tubes under concentrated lateral impact loads

Large diameter steel tubes are widely used in bottom fixed and floating offshore wind turbines. Offshore wind turbines (OWTs) operating in the oceans are exposed to the risk of collisions when ships pass and dock at turbines. Thus, it is extremely important to investigate the impact mechanics of ship-OWT collisions and propose practical designs for methods to protect OWTs from collision loads. This paper presents a series of experimental and numerical studies on the deformation behaviors of large diameter steel tubes from a NREL 5 MW spar-type floating offshore wind turbine (FOWT) under lateral impact loads. These studies consider the effects of different impact velocities, attached masses, diameters and thicknesses of the tubes on their response to impact loading. In these experiments, a rigid indenter was mounted on a pendulum system and accelerated to strike the tubes; the scale was 1:30. The dimensions of the indenter head were much smaller than the tube diameter in order to concentrate the impact load. Global motions of the impacted tubes were modeled by springs introduced at the boundaries, and their stiffnesses were determined according to an equivalent single-degree-of-freedom (SDOF) model. Numerical simulations of the experiments were conducted using the nonlinear finite element (FE) software LS-DYNA. The experimental and numerical results were compared and discussed with respect to force-deformation curves, deformation modes and energy dissipation. Existing theoretical solutions for the lateral indentation resistance of tubes were also compared to the experimental and numerical simulation data. The results indicated needs for new solutions when the impact loads become concentrated.

Lateral impact resistance of full-scale concrete-filled weathering steel tube columns

This paper conducted lateral impact tests on 10 concrete-filled weathering steel tubular (CFWST) columns and studied the effect of prestressing on their resistance to lateral impact. The results indicate that by using prestressed cantilever members, the impact resistance of the column can be significantly improved. This is mainly due to the reduction of tensile stress level in the steel tube at the fixed end of the cantilever column and of the overall plastic deformation of the member, which is achieved through the application of prestress. Furthermore, the test process was also simulated numerically. Based on verifying the correctness of the numerical simulation, the parameters of the full-scale model are analyzed. The impact resistance of the model was evaluated by considering various factors such as impact angle, impact point height ratio, prestress ratio, width-thickness ratio, slenderness ratio, and mass ratio. Based on these analyses, empirical formulas for the lateral ultimate displacement and bending moment of the cantilever members were derived. Particularly, considering the difference in yield strength between tension and compression sides, the theoretical calculation of plastic limit bending moment of concrete-filled square steel tubular members is modified. Additionally, the damage level of the component is defined, and the damage limit value of the concrete-filled steel tubular cantilever column is given based on the different damage grades. On this basis, considering the bending bearing capacity and displacement response of the component, an impact resistance design approach based on the performance of the component is proposed.

Effect of the axial load on the dynamic response of the wrapped CFRP reinforced concrete column under the asymmetrical lateral impact load.

This study investigated the impact of axial load on the dynamic response of reinforced concrete (RC) members to asymmetrical lateral impact loads. A series of asymmetrical-span impact tests were conducted on circular and square RC members with and without Carbon Fiber Reinforced Polymers (CFRP) while varying the axial compression ratios. The impact process was simulated using ABAQUS software, and the time history curves of deflection and impact were measured. The study found that specific impact loads caused bending and shearing failures. The axial compression ratio ranged from 0.05 to 0.13 when the impact curve reached its maximum deflection before the component's impact resistance decreased. Analysis of the impact point and inclined crack location revealed that axial load affects the maximum local concrete. The speed of inclined crack penetration and inclined cracks take longer to form, with weaker resistance to damage to local concrete when the axial compression ratio is between 0.05 and 0.13. When the axial compression ratio is greater than 0.13, inclined cracks form sooner with more brittle and severe damage to the impact point's concrete. The study also identified key parameters affecting the dynamic response of RC members, including impact height, CFRP layer thickness, axial force, and impact location. Thicker CFRP layers in RC can improve impact resistance, especially when the impact location is farther from the center. However, there is a limit to the impact of axial force on this resistance.

An energy-based method for predicting the peak displacement of steel casing composite pile under lateral impact loading

Effective and convenient prediction of the peak displacement of piles under collision conditions facilitates the design framework preparation and pile damage evaluation. Hence, an energy-based method was proposed to predict the peak displacement of the widely used steel casing composite (SCC) piles under impact loading. The pile deformation energy was first calculated based on its deformation characteristics and the relationship between the sectional bending moment and curvature. The pile deformation energy and pile–soil energy distribution ratio were then employed to determine the relationship between the total absorbed impact energy and pile head displacement, which was represented by curves. The peak pile displacement under lateral impact loading was finally obtained by interpolating the absorbed impact energy curves. By conducting sectional analysis of the pile considering the strain rate effects and using a structural pushover procedure, the peak pile head displacements for various collision cases were predicted with reasonable accuracy. The effectiveness and reliability of the proposed method were verified by comparing its results with those of previous reduced-scale impact tests and validated full-scale finite element models.

Study on the Vibration Displacement of Hydraulic Pipeline System Excited by Fluid Impact

Hydraulic impact had an effect on pipeline vibration displacement, so it was important to study the external lateral impact periodic force on fluid-structure coupling vibration displacement of hydraulic pipeline. Based on Bernoulli beam model, the fluid-structure coupling vibration equation of flexible pipeline was established by analyzing the stress of flexible pipeline under the action of internal flow. The hydraulic system pipeline was simulated whether the pipeline was subject to periodic impact force. The displacement-time curves in x, y and z directions of vibration monitoring points of hydraulic flexible pipelines were obtained, and the maximum displacement-time curves of fluid-structure coupling vibration under different pressure hydraulic impact were obtained. The simulation results were shown that the vibration of monitoring points in x, y and z directions of hydraulic impact pressure increased and the total displacement of the pipeline middle section of the hydraulic system decrease continuously, and then they tend to stabilize after a period of attenuation. The maximum displacement value of the X-direction monitoring point in the middle part of the hydraulic system pipeline was 9.5e −5 m, and the displacement vibration was stable at 0.135s. The maximum y-displacement was 3.1e −4m, and the vibration was stable at 0.2 s. The maximum z displacement was 1.32e-4 m, and the vibration was stable at 0.36 s. The total displacement was 3.35e −4 m, and the vibration was stable at 0.43s. Increasing the impact pressure, the maximum displacement of the hydraulic pipeline vibrations were larger, and the attenuation of the maximum values were faster. The research results provide a reference for the hydraulic system to prevent pressure shock and reduce vibration.

Incremental design process for vehicle structural components using thermoplastic-based composites: A simulation-guided approach for door anti-intrusion beams

The design of safety-related structural components in automobiles is a critical phase. Most car manufacturers are aiming at reducing vehicle weight considering continuous fiber-reinforced thermoplastics as candidate to replace metal-based structural components. However, this replacement cannot compromise the safety level already achieved by metal-based designs. A good example is the side door anti-intrusion beam, which is a passive safety component to protect the passengers under a lateral impact. This paper presents an incremental design process to achieve a functional side door anti-intrusion beam fully made of glass fiber reinforced thermoplastic conceived to replace metal-based ones. The reader is guided along the design challenges, where the mechanic-based reasons to adapt the part geometry and composite layout are explained in detail. This incremental design process uses a fully FEM-based approach allowing to reach a standard-defined absorbed energy of 1000 J in a lateral collision. From the simulation analysis, it was found that by implementing essential modifications in the beam’s cross-section corrugation, the damage progression can be slowed down leading to an increase of absorbed energy. Additionally, the enhancement of one extra ply in the proper direction solves severe fracture in the clamping area. The final composite design not only performs similarly to its metal-based counterpart, but also considers aspects of production feasibility. This trip along the design process concludes with the production of the simulate-designed component and its effectiveness under lateral impact is demonstrated. To meet the safety regulations, the model is thoroughly validated against the real impact test by analyzing the response in force, intrusion, energy and damage.

Assessment on concrete constitutive models for numerical simulations of vehicular collisions with RC bridge piers

Accident statistics showed that vehicular collision caused serious shear damage or failure of reinforced concrete (RC) bridge piers and even resulted in overall collapse of bridge structures. For the resistance evaluation of RC components under impact loads, numerical simulations have been performed by adopting different concrete constitutive models and obtained different results, e.g., Karagozian and Case Concrete (KCC) model and Continuous Surface Cap (CSC) model widely used, as well as Kong-Fang (KF) model recently proposed. This study mainly evaluates the accuracy of the above three concrete constitutive models in numerical analyses of vehicular collisions with RC bridge piers. Firstly, basic mechanical behaviors of these models are systematically compared based on single element simulations. Then, the scope of investigation is extended to component level by simulating a drop hammer test on RC beam and a lateral impact test on RC column, and the dynamic behaviors of impacted RC components are deeply compared. Finally, these models are further compared at structure level through performing the refined numerical simulation of a real truck colliding with a prototype bridge and evaluating its global structural behaviors and damage. The results show that, (i) KF model well reflects the post-peak softening behavior, stable strain-rate effect and independence of mesh size of concrete materials under uniaxial loading conditions at different loading rates; KCC and KF models both capture the brittle to ductile transition of concrete materials with increasing confinement pressure; (ii) KF model yields a better prediction in dynamic responses and damage characteristics of impacted RC beam and column, while KCC and CSC models both overestimate the damage degree; (iii) KF model better simulates the shear failure of RC pier in the real accident and provides the reasonable structural dynamic responses, but KCC and CSC models much underestimates the damage degree of impacted bridge pier and adjacent components.

The effect of humeral component retroversion on external rotation and shoulder function outcomes in patients undergoing reverse total shoulder arthroplasty with a lateralized glenoid component

BackgroundDeficits in shoulder external rotation create significant limitations in activities of daily living, including eating and reaching the top of the head. Reverse total shoulder arthroplasty (rTSA) changes the mechanics of the shoulder and improves forward elevation reliably, but external rotation deficits frequently persist. There is currently a wealth of information regarding the impact of glenoid component lateralization, neck shaft angle, and angulation of the glenoid component on external rotation. However, the impact of humeral component retroversion is less understood. The purpose of this study was to compare strength and range of motion in external rotation of patients undergoing rTSA at different degrees of humeral retroversion. We hypothesized that humeral retroversion at 30 degrees would result in superior external rotation and strength postoperatively than 0 degrees of retroversion. MethodsThis is a retrospective study of prospectively collected data on patients who underwent rTSA with either 0 or 30 degrees of humeral component retroversion between November 2016 and 2018. A 36-mm-sized glenosphere with a system that lateralizes off the glenoid was utilized in all patients. Patient demographic information and postoperative outcomes at 3 months, 6 months, and latest follow-up including degree of external rotation, strength in external rotation, visual analog scale for pain, Simple Shoulder Test score, and American Shoulder and Elbow Surgeons score were recorded. ResultsOutcomes for 38 patients were included (N = 18 at 0-degree; N = 20 at 30-degree). No preoperative difference was observed between the two cohorts. There was no significant interaction between time and retroversion for any variable (P ≥ .16). Time had a significant effect on all outcomes (P ≤ .002) except for internal rotation (P = .17). Retroversion did not have a significant effect on outcomes at any time point (P ≥ .07), though external rotation strength nearly reached significance (P = .07). External rotation at the side increased from 25.0 to 35.3 degrees and external rotation in abduction increased from 39.2 degrees to 63.4 degrees from 3 months to final follow-up. External rotation at the side strength increased from 1.6 kg to 1.8 kg and external rotation in abduction strength increased from 1.2 kg to 1.7 kg from 3 months to final follow-up. ConclusionsNo differences in outcomes were observed between 0° and 30° of humeral component retroversion. Strength in external rotation may be impacted by humeral component retroversion. Further clinical studies with larger sample sizes are needed to study the impact of humeral component retroversion on external rotation strength.

A Torn Discoid Lateral Meniscus Impacts Lower-Limb Alignment Regardless of Age: Surgical Treatment May Not Be Appropriate for an Asymptomatic Discoid Lateral Meniscus.

A discoid lateral meniscus (DLM) is more prone to tear, and treatment of this condition is challenging. The purpose of the present study was to investigate (1) whether a torn DLM is associated with more varus alignment than a torn semilunar lateral meniscus (SLM) and (2) whether the lower-limb alignment associated with a torn DLM changes with age. Consecutive patients who underwent arthroscopic knee surgery for a torn lateral meniscus were included. Patients with a torn DLM (confirmed on arthroscopy) were allocated to the DLM group; those with a torn SLM were allocated to the SLM group. After strict screening according to the inclusion and exclusion criteria, 436 and 423 patients were included in the DLM and SLM groups, respectively. The mechanical axis deviation (MAD), hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle, and medial proximal tibial angle were compared between the 2 groups after propensity score matching. Additionally, the correlation of the HKA and MAD with age was evaluated within the DLM group. After propensity score matching, all baseline characteristics were well balanced between the 2 groups. The DLM group had significantly more varus alignment than the SLM group (MAD: 3.6 mm ± 9.6 mm versus 1.1 mm ± 10.3 mm, respectively, p = 0.001; HKA: 179.1° ± 2.9° versus 179.9° ± 3.0°, respectively, p = 0.001). Within the DLM group, the MAD (R = 0.10, p = 0.032) and HKA (R = -0.13, p = 0.007) had a weak correlation with age. Patients with a torn DLM had more varus knee alignment than those with a torn SLM, and this trend did not increase with age after minimizing the effects of osteoarthritis. Therefore, surgical treatment may not be appropriate for asymptomatic DLM. Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Influence of stirrup ratio on vehicular impact resistance of double-column RC bridge piers

Vehicular collision is a typical lateral consecutive impact process. Under such an impact process, reinforced concrete (RC) bridge piers commonly suffer shear failure or punching-shear breakage, which could further cause the collapse of the bridges, especially for the simply-supported double-column RC bridges. The current work experimentally and numerically investigates the influence of stirrup ratio on the lateral consecutive impact resistance of double-column RC bridge piers (DCBPs). Firstly, a scaled lateral consecutive impact test is conducted on three DCBP specimens (containing impacted pier, adjacent pier and bent cap) to examine the influence of stirrup ratio on the dynamic behaviors at component level. Then, finite element (FE) models of the impact test are established and validated against the experimental results. Finally, refined numerical simulations of light, medium and heavy trucks colliding with a prototype simply-supported double-column RC bridge are performed at structural level to analyze the influence of stirrup ratio on dynamic shear capacity and deformation of the impacted RC piers, and anti-collapse performance of the bridges. The results derive that, (i) The impacted piers exhibit shear failure at the impact location, and the damage degree is significantly reduced with increasing stirrup ratio. However, the damage degree of adjacent piers and bent caps is not obviously influenced by the change of stirrup ratio; (ii) A higher stirrup ratio effectively achieves less stiffness degradation and smaller lateral deformation of the impacted piers under the first impact, that allows DCBPs to resist a higher second impact force; (iii) The deformation shape of the impacted piers is changed from the localized deformation to the global deformation with the increase of stirrup ratio, while such a variation does not occur to the adjacent piers; (iv) As the stirrup ratio increasing, the simply-supported double-column RC bridge can withstand a higher dynamic shear demand induced by vehicular collisions, and therefore decreases the global damage and collapse probability, especially when subjected to heavy truck collisions.

Investigation on lateral impact resistant performance of aluminum foam-filled 6082-T6 aluminum alloy circular tubes: Experimental and numerical study

Nowadays, the aluminum alloy building structure is at risk of the accidental impact loadings, which seriously threatens the personal security and the safety of the property. However, the existing research on the local lateral impact performance of the aluminum foam-filled tube applied to building structures is limited. In this study, impact tests on 9 aluminum foam-filled tubes with fixed boundaries were conducted by using a drop hammer impact test device to investigate the dynamic performance of the foam-filled tube under local lateral low-velocity impact loadings. The failure modes, impact force histories, displacement histories, and permanent deformation of the foam-filled tubes were obtained and compared with those of the empty tubes under the same impact loading. The finite element (FE) model was also established via the software ANSYS/LS-dyna and the accuracy of the FE method was verified against impact test results. Based on the experimental and numerical results, the aluminum foam-filled aluminum tube shows better lateral impact resistant performance than the empty tube due to the support effect of the aluminum foam on the tube wall by good energy absorption and deformation characteristics. Especially, filling the aluminum foam prevents the generation of cracks for the composite tube near the impact position when the impact energy is high. The influence law of the aluminum foam filler and its density, shape of hammer head on the lateral impact resistant performance of the aluminum foam-filled composite tube was then investigated based on the experimental and numerical results by consideration of the damage level, energy absorption, impact force–lateral displacement relationship, and permanent deformation. By filling the aluminum foam into the empty tube, the energy absorption is improved by up to 67.2% and 44.9%, respectively, when the hammer displacement reaches 20 mm and 40 mm within the impact load condition conducted in this study.