Dynamic Bearing Capacity Research Articles

Surface roughness measurement in the notch area for estimating dynamic component load bearing capacity

The surface of a part can have an essential influence on its dynamic load bearing capacity as grooves and scratches act as more or less significant imperfections or additional micro-notches, depending on the interpretation. In order to accurately predict the fatigue strength, detailed knowledge of the surface structure in critical areas is essential but cannot always be established due to geometric constraints. To overcome these restrictions, a method utilizing impressions and a laser scanning microscope to take surface topography measurements in critical notch areas is used in this work. It enables precise and reproducible measurements to be taken. The method is used to conduct surface roughness measurements on fatigue strength specimens made of four different materials. Several roughness influence factors are calculated based on the results and their influence on the result of a recalculation using a fatigue strength assessment is shown as example. The calculated fatigue limit is compared against experimental results. The comparison shows significant scatter in prediction accuracy and no optimal surface influence factor can be recommended so far. It has to be noted that only a small sample of specimens, which were not designed for researching surface roughness influence in particular, were available for this work. The effects of roughness in the notch may not be completely captured by the available roughness influence factors. Furthermore, issues arise in the correct implementation of stress concentration factor based roughness influence factors. Further research is required to provide a more comprehensive understanding of the effects of surface roughness on the fatigue limit.

Free-Drop Experimental and Simulation Study on the Ultimate Bearing Capacity of Stiffened Plates with Different Stiffnesses under Slamming Loads

Differing from previous studies on free-drop tests, this study focuses on the ultimate bearing capacity and failure mechanism of the ship’s bow under slamming loads. A prototype ship’s bow is selected to design two simplified stiffened plates with different stiffeners, and the lateral slamming loads used are equivalent to flare slamming loads. Free-drop tests of the two simplified models are conducted, and the test setups and procedures are provided. The experimental results of slamming pressures and structural responses are obtained. By comparing with the simulation results obtained by Arbitrary Lagrangian-Eulerian (ALE) fluid–structure coupling, the convergence study, symmetry, and independence verifications are carried out. Finally, the dynamic ultimate bearing capacity of stiffened plates with different stiffnesses under lateral slamming loads is studied. The results show that stiffeners enhance the ability of stiffened plates to resist plastic deformation under slamming loads, and T-section stiffeners can provide greater resistance to plastic deformation than other types.

Dynamic properties of alkali residue-based foamed concrete under cyclic load

Alkali residue-based foamed concrete (A-FC), consisting of cement, alkali residue, blast furnace slag, and foam, has great potential for application in subgrade engineering. A series of dynamic triaxial tests were conducted, and the influences of confining pressure, vibration frequency, and curing age on the dynamic properties of A-FC was revealed. Test results indicated that the backbone curves of A-FC exhibit a hyperbolic shape, effectively captured by the H-D model. After 7 days of curing, A-FC possessed robust dynamic bearing capacity. As the dynamic strain increases, the dynamic elastic modulus of A-FC exhibits an initial rise followed by a gradual decline. Concurrently, the damping ratio demonstrates an initial decrease and subsequent gradual increase. Elevated confining pressure, prolonged curing age, and higher vibration frequency were found to contribute to a progressive increase in the dynamic elastic modulus of A-FC. Throughout the damping ratio growth stage, the increasing curing age and confining pressure led to the decrease of damping ratio, with minimal influence from vibration frequency. A calculation model for the maximum dynamic elastic modulus of A-FC was proposed, considering confining pressure, vibration frequency, and curing age. This research underscores the capacity of A-FC to withstand cyclic loading, thereby offering valuable support for its engineering applications.

In-plane compression behaviors of novel reentrant double arrowhead honeycombs with two plateau stress regions

Combining reentrant honeycomb (RH) and double arrowhead honeycomb (DAH), the reentrant double arrowhead honeycomb (RDAH) is proposed. The deformation modes and compression behavior of the RDAH are numerically simulated and compared with the RH. The results show that the RDAH has a better specific energy absorption SEA than the RH regardless of low velocity or high velocity impact. Compared with the RH, the SEA of the RDAH increased by 9.4% under an impact velocity of 1 m/s and increased by 24.4% under an impact velocity of 100 m/s. The mechanical properties of the RDAH under different impact velocities and relative densities were further discussed, and empirical formulas were established based on the deformation mode map to predict the dynamic bearing capacity of the RDAH. Finally, the influence of the cell number on the in-plane compression of the RDAH is discussed, and it is found that an RDAH larger than 4 × 4 can produce more stable deformation. The influence of different cell vertical ligament heights h and relative densities on the mechanical properties of the RDAH is researched parametrically. The increase in the unit vertical ligament height h will reduce the SEA and destroy the stable deformation of the RDAH. SEA increases almost linearly with increasing relative density.

Lessons learned from large-scale physical modeling of tapered jacking piles: HSDT

To provide an improved understanding of the behavior of screw piles in disturbed soil, as a series of companion papers, laboratory tests with full scale tapered jacking piles were performed in the current study. The designated tapered pile has the similar dimensions, material properties and cone-shaped bottom, with the exception of threads eliminated.
 The main objectives of this paper are to: (1) establish the robust and efficient simple high strain dynamic testing (HSDT) requirements for validating displacement tapered piles capacities while exploring the installation effect; (2) determine a correlation between static and dynamic bearing capacity in compression for steel tapered piles installed by jacking in sand with various relative densities.
 Out of nine large-scale laboratory expriments at Aalborg University Offshore Geotechnics Laboratory [1-3] with the tank filled with Aalborg University Sand No.1, this research exclusively presents some lessons learned from an exemplar tapered jacking pile installation (Test 4) in dry sand (relative density and its response to monotonic and impact loadings. The selected piles have diameter of D=76 mm and 89 mm with length of 2.07 m. The layout of the miniature CPTs carried out to measure soil state is shown in Fig. 1, with four CPTs performed following each jacking installation campaign to study the soil state after the installation of the piles (Fig. 1). In order to fulfill the objectives, the piles are installed by a static compression load that includes an unloading/reloading step, followed by dynamic testing in order to facilitate the determination of the bearing capacity (Fig. 2). The hammer test was carried out on both piles, by a hammer from increasing drop heights of 218, 418, 618, 818 and 1018 mm (Fig.3). The hammer consists of a sleigh with multiple attached steel plates weighting 19.31 kg on average and the sleigh itself weighs 18.55 kg. Tapered pile jacking resulted in dilation extending to a depth of 2.8when diameter exceeds from 76 mm to 89 mm. By contrast, in the region around pile P76, the soil was entirely densified. The tendency to densify the soil near tip area due to jacking installation is observed in both tests, where the initial viod ratio varied from 0.67 to 0.59 and from 0.63 to 0.57 corresponding to piles P76 and P89, respectively (Fig.4).
 Subseuqntluy, Danish Pile Driving Formulas (DDR) introduced by [4] was ustilised which is according to the required potential energy from a hammer stroke to exceed the pile penetration resistance. The mass of the hammer G is defined by:
 where elastic settlement =, A is cross-sectional area, E is the Young’s modulus, l is the installed length of pile which is approximately 1.9 m, and is the maximum static force required to install the pile. The efficiency factor is set as 1. During the impact loading tests, the settlement of the pile is measured with a 1 mm accuracy for each hammer stroke, and the limiting settlement, s was set to yield a certain level (0.1D) when the drop height is 618 mm. Thus, the dynamic bearing capacity = , and ratio= are shown in Table 1.

Experimental investigation of the response of guardrail posts embedded in road shoulder material under quasi-static and dynamic impact loading

The main functions of vehicle restraint systems (VRS) are to redirect errant vehicles and prevent them from entering an opposing lane or carriageway, as well as preventing them from colliding with structures along the road [1]. In the case of steel guardrail systems, fulfilment of these requirements greatly depends on the soil-post interaction, which influences the deformation and energy dissipations of the VRS during impact.To date, there is no unified method of modelling the behaviour of guardrail posts embedded in road shoulder material in crash tests simulations. For this reason, the influence of soil type and state as well as post characteristics on the observed motion of vehicle and VRS cannot be adequately evaluated, which is, however, necessary to improve and optimise a VRS without increasing the number of crash tests.This paper presents the findings of a series of static and dynamic full-scale loading tests conducted with different road shoulder materials and post types, the aim being to create an experimental database for modelling the soil-post interaction in crash test simulations. The novel dynamic and static testing techniques used ensures repeatability and enables the reliable evaluation and interpretation of the results.We found that not only the static and dynamic post response but also the failure mode are significantly influenced by the relative soil density and post embedment length. As long as there is no yielding of the post section, the dynamic post resistance varies with increasing impact energy until a maximum value, which depends on the dynamic horizontal bearing capacity of the post. Any further increase in impact energy has no influence on the post resistance.

Study on dynamic response of high speed train window glass under tunnel aerodynamic effects

PurposeThis paper aims to analyze the bearing characteristics of the high speed train window glass under aerodynamic load effects.Design/methodology/approachIn order to obtain the dynamic strain response of passenger compartment window glass during high-speed train crossing the tunnel, taking the passenger compartment window glass of the CRH3 high speed train on Wuhan–Guangzhou High Speed Railway as the research object, this study tests the strain dynamic response and maximum principal stress of the high speed train passing through the tunnel entrance and exit, the tunnel and tunnel groups as well as trains meeting in the tunnel at an average speed of 300 km·h-1.FindingsThe results show that while crossing the tunnel, the passenger compartment window glass of high speed train is subjected to the alternating action of positive and negative air pressures, which shows the typical mechanic characteristics of the alternating fatigue stress of positive-negative transient strain. The maximum principal stress of passenger compartment window glass for high speed train caused by tunnel aerodynamic effects does not exceed 5 MPa, and the maximum value occurs at the corresponding time of crossing the tunnel groups. The high speed train window glass bears medium and low strain rates under the action of tunnel aerodynamic effects, while the maximum strain rate occurs at the meeting moment when the window glass meets the train head approaching from the opposite side in the tunnel. The shear modulus of laminated glass PVB film that makes up high speed train window glass is sensitive to the temperature and action time. The dynamically equivalent thickness and stiffness of the laminated glass and the dynamic bearing capacity of the window glass decrease with the increase of the action time under tunnel aerodynamic pressure. Thus, the influence of the loading action time and fatigue under tunnel aerodynamic effects on the glass strength should be considered in the design for the bearing performance of high speed train window glass.Originality/valueThe research results provide data support for the analysis of mechanical characteristics, damage mechanism, strength design and structural optimization of high speed train glass.

Dynamic response and rockburst characteristics of underground cavern with unexposed joint

The existence of joints poses a challenge to the dynamic stability of underground caverns. To investigate the dynamic response of the underground cavern affected by an unexposed joint, a series of SHPB tests were conducted on the marble specimens with a cavern and differently distributed joint, including the cases of joint location dips of 0°, 56°, 90°, 134°, and 180° and the case of no joint. The discrete element method was also adopted to uncover the dynamic failure mechanism of samples. Based on the experimental and numerical results, the effects of joint distribution on the fracturing process, dynamic strength and local stress evolution of underground caverns were systematically investigated. The deformation characteristics, failure patterns, rockburst characteristics and rockburst mechanism were identified for different joint cases. The results showed that the joint has limited influence on the dynamic bearing capacity and failure characteristics of the cavern when the dip θ = 0°, 90° and 180°, but it becomes significant when the dip θ = 56° and 134°. Similarly, when the dip θ falls in the range of 56°∼134°, the maximum principal stress around the cavern will be significantly affected, but not when the dip θ is 0° or 180°. More specifically, different joint distributions can cause four kinds of rockbursts on the cavern: A) strain rockburst at the roof; B) strain rockburst at the floor; C) slip rockburst of wing cracks at the roof; and D) slip rockburst of wing cracks at the floor. When these rockbursts occur, the displacements of surrounding rocks will demonstrate obvious abnormal changes (e.g., characteristic oscillations and sudden changes), and C-type rockbursts generally lag behind A-type rockbursts. In addition, the magnitudes of the strain energy release rate can be identified: D-type rockburst > A-type rockburst > B-type rockburst > C-type rockburst > no rockburst. The findings of this study will benefit the stability analysis and risk control of underground caverns.

Analysis of influencing factors on gas film characteristics for hemispherical dynamic pressure motors

The hemispherical dynamic pressure motor (HDPM) has the advantages of high speed, wear resistance and stability, which is widely used in inertial instruments to produce the gyroscopic effect. The ultra-thin gas film between the stator and rotor of the motor provides dynamic pressure lubrication and bearing capacity, whose dynamic characteristics determine the motor performance. However, the influence mechanism of some key factors such as ball center distance on the film characteristics is not clear, which has become the bottleneck restricting the performance improvement of HDPMs. Therefore, in this paper, a series of gas film similarity models were solved under different geometric and working parameters, and the influence law of the ball center distance, rotor displacement and stopping process on the aerodynamic characteristics was obtained, the results show that these primary parameters have significant effects on the pressure distribution, resistance moment and frictional heat of the ultra-thin gas film. This work can not only provide a theoretical basis for the aerodynamic performance optimization of HDPMs, but also serve as a reference for the design of other aerodynamic instruments.

Mechanical Performance Analysis of Hydrostatic Thrust Bearing under Microbevel Parameters

Background: Heavy-duty hydrostatic bearings of the original parallel friction pair are prone to hydrostatic loss problems during operation. Aims: To solve the failure problem, the original hydrostatic oil pad was designed as a micro-inclined plane, and the dynamic pressure caused by the micro-wedge of the oil pad at a higher speed was used to compensate for the static pressure loss of the bearing. objective: For a new type q1-205 microbevel double rectangular cavity hydrostatic bearing. Objective: This study aims to design a new type of q1-205 micro bevel double rectangular cavity hydrostatic bearing. Method: The mathematical model of oil film theoretical analysis of hydrostatic bearing with the micro-inclined surface was established, including the flow equation of a double rectangular cavity with a micro-inclined surface and static and dynamic bearing capacity equation. result: The oil film lubrication performance of the bearing with the wedge parameters of 0mm, 0.02mm, 0.04mm, 0.06mm, 0.08mm and 0.10mm was simulated by the finite volume method, the comprehensive influence law of the wedge-shaped parameters on the vorticity and flow rate of the oil cavity pressure fluid was revealed. Finally, the oil cavity pressure changes of oil films with different wedge parameters under certain load and speed were tested by design experiments, and the theoretical analysis and simulation were verified. Result: In this paper, the mechanical properties of oil film with tilt height between 0 and 0.1mm were simulated with variable viscosity, and the distribution law of pressure field under different working conditions was obtained. Through the experimental study, the pressure data of parallel flat pads and tilting pads under different working conditions are measured and compared with the simulation data. Conclusion: The pressure loss value of the oil pad designed in this paper is relatively small under extreme working conditions. The overall loss rate is about 10% ~ 20%, and the dynamic pressure compensation rate is about 16%. The dynamic pressure generated by the slight inclination Angle can well compensate for the static pressure loss.

Effect of dynamic loading conditions on the dynamic performance of MP1 energy-absorbing rockbolts: Insight from laboratory drop test

Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the split-tube drop test with varying impact energy was conducted to reproduce the dynamic performance of MP1 rockbolts under a wide range of seismic event magnitudes. The test results showed that the impact process could be subdivided into four distinct stages, i.e. mobilization, strain hardening, plastic flow (ductile), and rebound stage, of which strain hardening and plastic flow are the primary energy absorbing stages. As the impact energy per drop increases from 8.1 to 46.7 kJ, the strain rate of the shank varies between 1.20 and 2.70 s−1, and the average impact load is between 240 and 270 kN, which may be considered as constant. The MP1 rockbolt has a cumulative maximum energy absorption (CMEA) of 31.9–40.0 kJ/m, with an average of 35.0 kJ/m, and the elongation rate is 11.4%–14.7%, with an average of 12.7%, both of which are negatively correlated with the impact energy per drop. Regression analysis shows that energy absorption and shank elongation, as well as momentum input and impact duration, conform to the linear relationship. The complete dynamic capacity envelope of MP1 rockbolts is proposed, which reflects the dynamic bearing capacity, elongation, and distinct stages. This study is helpful to better understand the dynamic characteristics of energy-absorbing rockbolts and assist design engineers in robust reinforcement systems design to mitigate rockburst damage in seismically active underground excavations.

Two approaches for analysis of the dynamic pile bearing capacity via pile driving formulas

Piling is considered the most cost-efficient solution in deep foundation structures, and it involves many modern-day solutions in every field, such as modern-day materials and construction equipment. However, analysis of pile bearing capacity that includes evaluating of soil conditions and its mechanical properties is relatively new compared to piling itself. Pile bearing capacity depends on two factors – the strength of the structural element itself and the resistance of the soil around the pile. This resistance must be enough to avoid excessive displacements, rotations and other movements that make the superstructure unstable. The structural strength of the pile itself could be determined, though soil resistance is affected by many factors. One of the pile bearing capacity establishment methods is pile driving formulas – equations that establish pile bearing capacity considering set per blow and hammer impact energy. However, given establishment approach is considered unreliable and out of date, although this approach has several advantages – fast execution and minimum additional equipment required. Paper deals with two approaches for analysing the dynamic pile bearing capacity via pile driving formulas and correlation establishment between dynamic load test and static load test. In paper correlation between both dynamic pile bearing capacity approaches and static load test is established.

Experimental Study on Vibration Velocity of Piled Raft Supported Embankment and Foundation for Ballastless High Speed Railway

In recent years, the high development of high-speed railway lines cross through areas with poor geological conditions, such as soft soil, offshore and low-lying marsh areas, resulting geotechnical problems, such as large settlements and reduction of bearing capacity. As a new soil reinforcement method in high speed railway lines, the piled raft structure has been used to improve soil conditions and control excess settlement. In order to study the dynamic behavior of piled raft supported ballastless track system in soft soil, an experimental study on vibration velocities of piled raft supported embankment and foundations is presented in soft soil with different underground water levels. Vibration velocities at specified positions of the piled raft supported embankment and foundations are obtained and discussed. The vibration velocity curves on various testing locations of piled raft foundations are clearly visible and have sharp impulse and relaxation pattern, corresponding to loading from train wheels, bogies, and passages. Vibration velocity distribution in the horizontal direction at three train speeds clearly follows an exponential curves. Most of the power spectrums of vibration velocity at various locations are mainly concentrated at harmonic frequencies. The change in water level has slight impaction on the peak spectrum of vibration velocity at harmonic frequencies. The vibration power induced by train loads are transmitted, absorbed, and weakened to a certain extent through embankment and piled raft structure. The dynamic response character of embankments are affected by their self-vibration characteristics and the dynamic bearing capacity of the piled raft structure.

Numerical Simulation Analysis on the Lateral Dynamic Characteristics of Deepwater Conductor Considering the Pile-Soil Contact Models

It is important to accurately assess the interaction between the conductor and the soil to ensure the stability of the subsea wellheads during deepwater drilling. In this paper, numerical simulations were carried out to study the lateral dynamic bearing capacity of the conductor considering different contact models between the conductor and the soil. In particular, the contact surface model and contact element model were selected to study the dynamic behavior of pile–soil under a transverse periodic load. On this basis, the influence of the bending moment, the wellhead stick-up, the outer diameter (O.D.) of the conductor and the wall thickness (W.T.) of the conductor, as well as the physical parameters of the soil on the dynamic bearing capacity are discussed in detail. Analysis results show that the lateral deformation, deflection angle and von Mises stress calculated by the contact element model are greater than those calculated by the contact surface model. The maximum value of the lateral deformation and bending moment of the conductor decrease with the O.D. and W.T. of the conductor, and the cohesion and internal friction angle of the soil. However, the maximum value of the lateral deformation and bending moment of the conductor increase with the wellhead stick-up. Both the vertical force and the soil density have a negligible effect on the lateral behavior of the conductor. This study has reference value for the design and stability assessment of subsea wellheads.

Wind-induced instability analysis of large-span single-layer lattice domes

This paper addresses the instability behaviour of single-layer lattice domes with a long span subjected to wind action. Two structural configurations with a span of 120 m and a rise-to-span ratio of 1:3 and 1:6 are analysed to compare critical dynamic loads to critical static loads. The Budiansky–Roth and phase-plane criteria are employed for estimating dynamic critical conditions. Wind fluctuation (Cpf) is simulated as a function of the average pressure coefficient (C¯p) over time, and the imperfections are set by means of the so-called “Conformable Imperfection Method”. The parameters considered in this research include the wind fluctuation, fluctuation period, geometric imperfection, and strengthening the members. It is found that the critical wind velocity reduces as the wind fluctuation increases. Furthermore, as the fluctuation period Tf increases, the difference between the static and the dynamic critical loads decreases. The use of Cpf=0.3C¯p and Tf/T1=1.0 (T1 being the fundamental period) produced the lowest amount of critical velocities of 50 and 43 m/s for D1:3 and D1:6 configurations, respectively. The corresponding critical dynamic loads were 29.27 and 15.15 kN giving the dynamic load ratio of 193%, the dynamic to static critical load ratios being 0.67 and 0.68 for these configurations. The D1:3 and D1:6 domes exhibited imperfection sensitivity by as much as about 17 and 82% load reduction, respectively, for an imperfection amplitude of Span/350. Strengthening the critical members of the D1:6 dome subjected to the wind action had the advantage of increasing the static instability load and the dynamic critical load bearing capacity by 20 and 30%, respectively. For estimating the equivalent static wind load, a reduction factor of 0.50 defined as the ratio of dynamic to static load was proposed.

Dynamic Response and Energy Absorption Characteristics of a Three-Dimensional Re-Entrant Honeycomb

In this paper, we design a new three-dimensional honeycomb with a negative Poisson’s ratio. A honeycomb cell was first designed by out-of-plane stretching a re-entrant honeycomb and the honeycomb is built by spatially combining the cells. The in-plane response and energy absorption characteristics of the honeycomb are studied through the finite element method (FEM). Some important characteristics are studied and listed as follows: (1) The effects of cell angle and impact velocity on the dynamic response are tested. The results show that the honeycomb exhibits an obvious negative Poisson’s ratio and unique platform stress enhancement effect under the conditions of low and medium velocity. An obvious necking phenomenon appears when the cell angle parameter is 75°. (2) Based on the one-dimensional shock wave theory, the empirical formula of the platform stress is proposed to predict the dynamic bearing capacity of the honeycomb. (3) The energy absorption in different conditions are investigated. Results show that as the impact velocity increases, the energy absorption efficiency gradually decreases. In addition, with the increase of cell angle, the energy absorption efficiency is gradually improved. The above study shows that the honeycomb has good potential in using in vehicle industry as an energy absorption material. It also provides a new strategy for multi-objective optimization of mechanical structure design.

Modified pseudo–dynamic bearing capacity of strip footing on rock masses

In this paper, the seismic bearing capacity of a strip footing sitting on rock masses has been investigated following the upper bound theorem of limit analysis. The generalized tangential technique is used to obtain the equivalent Mohr–Coulomb parameters of the modified Hoek–Brown criterion. Considering the damping characteristics of the site as well as the dynamic characteristics of the seismic waves, the modified pseudo-dynamic (MPD) method is applied to evaluate the seismic effects. A parametric study is conducted, which shows that the seismic acceleration coefficient, the geological strength index, the material constant of the intact rock, and the normalized frequency all have a significant effect on the seismic bearing capacity. The MPD results are also compared with other methods, including the conventional pseudo-dynamic (CPD) method, spectral pseudo-dynamic method (SPD), and pseudo-static (PS) method. A high degree of agreement can be observed between the MPD results and the CPD results as the normalized frequency increases. When the normalized frequency equals 0.5 + nπ, the values of the bearing capacity factor obtained by using the MPD method and the SPD method will hit their local minima, while the CPD and PS methods will overestimate the bearing capacity factor to a large extent.

COMPARATIVE ANALYSIS OF STATIC AND DYNAMIC PILE TESTS IN DIFFICULT GROUNDS OF KAZAKHSTAN

A comparative analysis of the results of field tests to determine the bearing capacity of a pile at the facilitys in the Nur-Sultan city and Petropavlovsk city. The aim of the study was to carry out a comparative analysis of the results of dynamic and static tests in the two construction site in order to identify the difference in performance. This article provides programs and results of tests with static indentation load and dynamic load on a pile in different two of the construction site under different soil conditions. The results of the comparative analysis are the following: Dynamic tests are needed for a preliminary assessment of the dynamic bearing capacity and the possibility of driving piles in different soil conditions. The bearing capacity of the pile, determined by dynamic tests, is slightly lower than during static tests, the difference between the results is 11 and 17%.

Experimental Research on the Seismic Characteristics of a Precast Frame Structure with a Viscous Damper

ABSTRACT Precast structures have become increasingly popular in recent years. However, the low seismic capacity of prefabricated structures is still a fraught issue in high seismic intensity regions. This paper aims to improve the structural seismic capacity of a precast concrete frame by employing a viscous damper. Two precast concrete frame specimens, with and without viscous dampers (PCFV and PCF), were produced and subjected to dynamic reversed cyclic loading tests. The experimental results showed that the viscous damper could improve the dynamic bearing capacity of the frames.

Dynamic bearing capacity of point fixed corrugated metal profile sheets subjected to blast loading

Blast loading scenarios and the corresponding hazards have to be evaluated for infrastructure elements and buildings especially at industrial sites for safety and security issues. Point fixed corrugated metal sheets are often applied as façade elements and can become a hazard for humans if they are pulled off. This paper investigates the dynamic bearing capacity of such structural members in terms of their general bending behavior in the middle of the span and pull-out behaviors at the fixing points. The elements are fixed at two sides and the load transfer is uniaxial. An experimental series with static and dynamic tests forms the basis to identify the predominant failure modes and to quantify the maximum stress values that can be absorbed until the investigated structural members fail. The experimental findings are applied to create and to optimize an engineering model for the fast and effective assessment of the structural response. The aim is the derivation of a validated model which is capable to predict the blast loading behavior of metal sheets including arbitrary dimensions, material properties, and screw connections. Results of this study can be integrated into a systematic risk and resilience management process to assess expected damage effects and the evaluation of robustness.