This paper proposes a passive vibration control device, series rolling-pendulum tuned mass damper (SRPTMD), with a “ball-in-ball” configuration. A conventional pendulum TMD (PTMD) generally requires a long cable length that usually exceeds one-story height for high-rise buildings. A rolling-pendulum TMD (RPTMD) is a mass that can roll on a base with a curvature instead of swaying with a cable, significantly reducing the requirement of vertical rooms. In addition, a ball-in-ball SRPTMD is equivalent to a system with two degrees of freedom in series. This study aimed to derive equations of motion of the primary building-SRPTMD system, conduct a parametric study for SRPTMD, and investigate the structural control performance of an SRPTMD. Results showed that an SRPTMD performed similarly to an RPTMD. One advantage of an SRPTMD is that the fundamental natural frequency of an SRPTMD can be altered to a certain extent by changing the radius ratio of the inner ball to the outer ball, whereas the natural frequency of an RPTMD can only be altered by changing the curvature of its base, which is far more difficult. Another advantage is that the two modal frequencies of an SRPTMD can be manipulated by selecting a specific set of radius ratios between the base, the outer ball, and the inner ball, which means that an SRPTMD has higher potential on multiple modes control.

In the last decades, the use of adhesives has rapidly increased in many industrial fields. Adhesive joints are often preferred to traditional fasteners due to the many advantages that they offer. For instance, adhesive joints show a better stress distribution compared to the traditional fasteners and high mechanical properties under different loading conditions. Furthermore, they are usually preferred for joining components made of different materials. A wide variety of adhesives is currently available: thermoset adhesives are generally employed for structural joints but recently there has been a significant increment in the use of thermoplastic adhesives, in particular of the hot-melt adhesives (HMAs). HMAs permit to bond a large number of materials, including metal and plastics (e.g., polypropylene, PP), which can be hardly bonded with traditional adhesives. Furthermore, HMAs are characterized by a short open time and, therefore, permit for a quick and easy assembly process since they can be easily spread on the adherend surfaces by means of a hot-melt gun and they offer the opportunity of an ease disassembling process for repair and recycle. For all these reasons, HMAs are employed in many industrial applications and are currently used also for bonding polypropylene and polyolefin piping systems. In the present paper, the dynamic response of single lap joints (SLJ) obtained by bonding together with a polyolefin HMA two polypropylene substrates was experimentally assessed. Quasi-static tests and dynamic tests were carried out to investigate the strain rate effect: dynamic tests were carried out with a modified instrumented impact pendulum. Relevant changes in the joint performance have been put in evidence. Failure modes were finally analysed and compared. A change in the failure mode is experimentally found: in quasi-static tests SLJ failed due to a cohesive failure of the adhesive, whereas in dynamic tests the SLJ failed due to an interfacial failure, with a low energy absorption.

In the Application for Construction Plan License after the Great East Japan Earthquake, it was needed to revalidate the damping ratio to apply 3% for seismic analyses of Reactor Coolant Loop (RCL) with two-point-support Steam Generators (SGs) which was normally 0.5% or 1% in the past Applications. For the revalidation, vibration tests of SGs were carried out at Unit 2 and Unit 3 in Mihama Power Station of the Kansai Electric Power Co., Inc. In the test at Mihama Unit 2, SG top was hit horizontally by the pendulum type hammering device. As a result, in the hot leg (HL) direction, 9% damping ratio has been obtained. In the test at Mihama Unit 3, electro-hydraulic actuators were installed at the top of reinforced concrete wall surrounding SG and SG upper manhole was excited. In the excitation test, frequency response curves were obtained by changing the frequency stepwise in sinusoidal wave at constant amplitude. The damping ratio has been confirmed as more than 3%, specified in JEAG 4601-1991 as standard value, in the HL perpendicular direction which provided smaller damping ratio compared to the HL direction. Dissipation energy of snubber was measured and it has been confirmed that snubbers themselves do not contribute damping effect for small SG displacement like tests in Mihama Unit 2 and Unit 3. Large dissipation energy of snubbers would be expected in earthquake. It has been realized that conservative large responses are computed in RCL seismic analysis if the damping ratios obtained are used.

NIST in Boulder Colorado investigated the correlations between impact test results obtained from standard, full-size Charpy specimens (CVN) and specimens with reduced thickness (sub-size Charpy specimens, SCVN) or reduced or scaled cross-section dimensions (miniaturized Charpy specimens, MCVN). A database of instrumented impact test results was generated from four line pipe steels, two quenched and tempered alloy steels, and an 18 Ni maraging steel. Correlations between specimen types were established and compared with previously published relationships, considering absorbed energy, ductile-to-brittle transition temperature, and upper shelf energy. Acceptable correlations were found for the different parameters, even though the uncertainty of predictions appears exacerbated by the expected significant experimental scatter. Furthermore, we report on the development of MCVN specimens for the indirect verification of small-scale pendulum machines (with potential energies between 15 J and 50 J), which cannot be verified with full-size verification specimens. Small-scale pendulum machines can now be verified at room temperature with certified reference specimens of KLST type (3 mm × 4 mm × 27 mm), supplied by NIST at three certified absorbed energy levels (low energy, 1.59 J; high-energy, 5.64 J; super-high energy, 10.05 J). These specimens can also be used to verify the performance of instrumented Charpy strikers through certified maximum force values. Certified reference values for both absorbed energy and maximum force were established by means of an interlaboratory comparison (Round-Robin), which involved nine qualified and experienced international laboratories.

Gas-structure coupling vibration is one kind of vibration caused by air pulsation. This coupling vibration causes widespread damage and deformation of three-stage cyclone separator used in Residue Fluid Catalytic Cracking (RFCC). After theoretically analyzing the mechanism of the generation of the gas-structure coupling vibration, the numerical simulation of three-dimensional swirling flow the cyclone separator was performed by using Reynolds Stress Model (RSM). The results showed the existence of processing vortex core (PVC) in the cyclone separator. The PVC phenomenon and motion of PVC were described in detail. Furthermore, the amplitude and frequency of gas fluctuation in the PVC region at different axial positions were quantitatively analyzed. The simulation results agreed with the experimental results of Laser Doppler Velocimetry (LDV). Finally, considering the characteristics of transient torsional pendulum of PVC in cyclone separator, the fluid-solid coupling dynamic characteristics of three-stage cyclone separator were analyzed by the finite element method, which provides references for the structure optimization design of new type cyclone separator.

This paper deals with the effectiveness of two isolation system for the seismic protection of elevated steel storage tanks. In particular the performance of High Damping Rubber Bearings and Friction Pendulum isolators has been analyzed. As case study an emblematic example of elevated tanks collapsed during the Koaceli Earthquake in 1999 at Habas Pharmaceutics plant in Turkey has been considered. A time-history analysis conducted using lumped mass models demonstrated the high demand in terms of base shear required to the support columns and their inevitable collapse due to the insufficient shear strength. A proper design of HDRB and FPS isolator and a complete non-linear analysis of the isolated tanks proved the high effectiveness of both isolation systems in reducing the response of the case tank. Actually, a reduced level of displacements of isolators and a reduced level of convective base shear obtained with the second isolation typology, suggested the used of FPS isolators rather than HDRB.

This paper describes an analytical and numerical study performed to benchmark LS-DYNA computer analysis of the response of a stacked spent fuel cask system to seismic base excitation. The LS-DYNA solution of the rocking block problem and stability of the block under the action of a base acceleration pulse are compared to the inverted pendulum solution first published by George W. Housner in 1963. Housner’s work has been cited by a number of subsequent investigations exploring the physics behind the rocking block problem, including Yim and Chopra [2]. The analytical formulation of the rocking block problem is derived in 2D in this paper. As is the case in many of the previous formulations, the solutions are provided after linearization of the governing equations. The stability of the unanchored block subjected to an acceleration pulse is solved using the energy method. The solution displays key differences relative to Housner’s minimum acceleration required to overturn. An alternate equation for effective viscous damping is also presented, which differs from the formulation given in Appendix A of ASCE 43-05 [9]. Simulation of the rocking block problem using LS-DYNA is shown to faithfully reproduce the classical solution, albeit at lower levels of energy loss. Effective damping and minimum acceleration to overturn from the LS-DYNA benchmark agree with predictions of the classical solution even after linearization.

In order to investigate the bidirectional characteristic of a multiple friction pendulum system (MFPS) with multiple sliding surfaces, a series of component tests were performed by using the shaking table in the National Center for Research on Earthquake Engineering, Taipei, Taiwan. The multiple friction pendulum system with multiple sliding surfaces consists of double concave surfaces, more than one intermediate sliding plates and one articulated slider located between the concave surfaces and intermediate sliding plates. These devices can continuously change their horizontal stiffness, damping, and displacement capacities during ground shaking by virtue of the properties such as radii and friction coefficients of multiple sliding surfaces. In this study, both uni- and bidirectional component tests of a multiple friction pendulum system with three and four sliding surfaces were carried out to investigate its mechanical characteristic. Furthermore, results obtained from the shaking table tests of an isolated steel structure demonstrate that the MFPS isolation system with multiple sliding surfaces could properly change its stiffness and damping effect, and effectively reduce the excitation force during ground shaking.

Presented in this paper is aimed at experimental evaluation of the efficiencies of the multiple direction-optimized friction pendulum system (MDO-FPS) with multiple sliding interfaces in mitigating the seismic responses of motion sensitive equipment through a series of shaking table tests. Experimental tests of motion sensitive equipment isolated with MDO-FPS isolators and subjected to various types of earthquakes were carried out to investigate the efficiency of the MDO-FPS isolator in reducing the response of equipment during earthquakes. Shaking table test results indicate that the acceleration response of the equipment has been remarkably reduced while compared to that of fixed-base equipment.

The seismic response of extra-large Liquefied Natural Gas (LNG) tank isolated vertically by multiple friction pendulum system (MFPS) is analyzed. The fundamental frequency of the extra-large LNG tank is usually the range of dominant frequency of most earthquake ground motions. It is an effective way to decrease the response for an isolation system being used for extra-large LNG storage tanks under the strong earthquake. However, it is rather difficult to implement in practice using common bearings because of low temperature, soft site and other severe environment factors. The extra-large LNG tank isolated by MFPS is presented in this study to solve these problems. MFPS is appropriate for large displacements induced by earthquakes with long predominant periods. A simplified finite element model by Malhotra and Dunkerly methods is used to judge the utility of the isolation system. Data reported and statistically sorted include pile shear, wave height, impulsive acceleration, convective acceleration and outer tank acceleration. The results show that the isolation system has excellent adaptability for different liquid levels and is very effective to control seismic response of the extra-large LNG tank.

Presented in this paper is the performance evaluation of the multiple friction pendulum system (MFPS) with multiple sliding interfaces on seismic mitigation through a series of shaking table tests of a full scale MFPS-isolated building. In the tests, a three-story steel building of 40 tons in total weight, 3m and 4.5m in two horizontal directions and 9m in height, was equipped with MFPS isolators each with 4 sliding interfaces and subjected to various types of earthquakes to examine the efficiency of the isolators in reducing seismic response of a structure. Experimental results from shaking table tests tells that the roof accelerations, base shears, column shear forces have been significantly lessened with negligible residual displacements in the isolators while compared to the responses of a fixed-base structure.

Current structural analysis software programs offer few if any applicable device-specific hysteresis rules or nonlinear elements considering the velocity effect on the mechanical behavior of the multiple friction pendulum system (MFPS) with numerous sliding interfaces. Based on the concept of subsystems, here we propose an equivalent series system that adopts existing nonlinear elements with parameters systematically calculated and mathematically proven through rigorous derivations to take into account the velocity dependence effect on the sliding behavior of the sliding interfaces in the sliding type base isolators. Evaluations of the velocity dependence effect on the features of the sliding motions on numerous sliding interfaces have also been carried out. Results from the given examples demonstrate that the sliding motions of sliding interfaces considering velocity dependence behave quite differently from those excluding the effect of velocity dependence.

This paper is aimed at the performance evaluation of the multiple direction-optimized friction pendulum system (MDO-FPS) with multiple sliding interfaces on seismic mitigation through a series of shaking table tests of a full scale building isolated with MDO-FPS isolators. Experimental tests of a three-story steel building of 40 tons in total weight, 3m and 4.5m in length and width, respectively, in two horizontal directions and 9m in height, subjected to various types of earthquakes were carried out to investigate the efficiency of the isolators in reducing structural responses during earthquakes. Results obtained from the shaking table tests demonstrate that the roof accelerations, base shears, column shear forces have been remarkably reduced while compared to the responses of a traditionally designed structure.

In this paper, a base isolator call the multiple direction optimized-friction pendulum system (Multiple DO-FPS) with numerous sliding interfaces is proposed. For understanding the mechanical behavior of the Multiple DO-PFS isolator under multi-directional excitations, an analytical model called the multiple yield and bounding surfaces model is also proposed. On the basis of the derived mathematical formulations for the simulation of the characteristic of the Multiple DO-FPS isolation bearing, it is revealed that the natural period and damping effect for a Multiple DO-FPS is a function of the sliding displacement and sliding direction. By virtue of the proposed model, the phenomena of the sliding motions of the Multiple DO-FPS isolator with numerous sliding interfaces subjected to multi-directional excitations can be simply understood. Analytical results infer that the natural frequency and damping effect of the Multiple DO-PFS isolator with numerous concave sliding interfaces change continually during earthquakes and are controllable through appropriate designs.

The multiple trench friction pendulum system (MTFPS) which has numerous sliding interfaces in each of two perpendicular directions can provide different natural periods, displacement capacities and damping effects at various levels of displacements in the individual direction. In order to characterize the mechanical behavior of the MTFPS isolator under multi-directional earthquakes, a plasticity model named as the multiple yield and bounding surfaces model is proposed in this study. Investigations for buildings isolated with TFPS isolators and subjected to multi-directional excitations have been carried out to assess the performance of the MTFPS isolation bearing in seismic mitigation through numerical analyses. Results from numerical analyses illustrate that the MTFPS isolation bearing can isolate most earthquake induced energy and provide good protection for structures from earthquake damage.

In Japan, applications of seismic isolation systems to new generation nuclear power plants and fast breeder reactors have been expected in order to enhance seismic safety. However there are lots of restrictions for design of isolation systems, such as strong design seismic wave, deformation of piping between an isolated structure and a non-isolated structure, and so on. In addition combination of horizontal and vertical isolation has possibility to cause rocking motion if a three-dimensional isolation system is applied. Therefore isolation systems should be designed properly. Moreover the design of seismic isolation system has to consider influence on inner equipment and piping. This paper describes investigation regarding required properties and performance of seismic isolation system for nuclear power plants. The investigation is carried out by numerical analysis. In the analysis, various isolation devices such as friction pendulum bearings and so on are applied as well as natural rubber bearings.

In order to prevent a building from earthquake damage, a base isolation system called the multiple friction pendulum system (MFPS) which has numerous concave sliding interfaces is proposed to isolate a building from its foundation. Mathematical formulations have been derived to simulate the characteristic of the MFPS isolation system subjected to multi-directional excitations. By virtue of the derived mathematical formulations, the phenomena of the sliding motions of the MFPS isolator with several concave sliding interfaces under multi-directional earthquakes can be clearly understood. Also, numerical analyses of a building isolated with the MFPS isolator with several sliding interfaces have been conducted in this study to evaluate the efficiency of the proposed system in seismic mitigation. It has been proved through numerical analyses that structural responses have been reduced significantly and that the proposed system is a good tool to insure the safety of structures during earthquakes.

Presented in this paper is the detailed mechanical characteristic of the multiple direction optimized-friction pendulum system. Based on the equilibrium equations, mathematical formulations describing the sliding motions of the multiple direction optimized-friction pendulum system have been derived. The mechanical behavior of the multiple DO-FPS isolation system under cyclic loadings has been investigated. The parametrical study for the multiple DO-FPS isolation bearing has also been carried out to realize its various characteristics under different parameters. It is demonstrated that the natural period and damping effect of the multiple DO-FPS isolator are a function of the sliding direction, displacement and coefficient of friction.

In order to systematically investigate the mechanical characteristic of a multiple friction pendulum system with more than two concave sliding interfaces and one articulated slider located between these concave sliding interfaces, on the basis of the plasticity theory, a plasticity model called the multiple yield and bounding surfaces model is proposed in addition to analytical formulations derived from the proposed concept of subsystems in this study. The proposed model has two separate groups of multiple yield and bounding surfaces. The first group is adopted to describe the mechanical behavior of the subsystem including the concave sliding interfaces above the articulated slider and the second group is used for modeling the sliding characteristic of the subsystem representing the concave sliding interfaces below the articulated slider. The connection of these two subsystems in series forms the mechanical characteristic of the entire MFPS isolation system. By virtue of the proposed model, the phenomena of the sliding motions of the MFPS isolator with multiple concave sliding interfaces under cyclical loadings can be clearly understood. Analytical results infer that the natural frequency and damping effect of the MFPS isolator with multiple concave sliding interfaces change continually during earthquakes and are controllable through appropriate designs.

In order to upgrade the seismic resistibility of structures and enhance the functionality of an isolator, a new sliding type base isolator system called the multiple trench friction pendulum system (MTFPS) with multi-intermediate sliding plates is proposed. The MTFPS isolator is composed of a trench concave surface and numbers of intermediate sliding plates in each of two orthogonal directions. Mathematical formulations have been derived to examine its characteristics of the proposed MTFPS isolator. Based on mathematical formulations, it can be inferred that the natural frequency and damping effect of the MTFPS isolator change continually during earthquakes. Furthermore, results from shaking table tests demonstrate that the proposed isolator provides good protection to structures for preventing damage from strong earthquakes.