Isolation Layer Research Articles

Seismic Isolation Measures of Plate-Shell Integrated Concrete Liquid-Storage Structure

In order to study isolation measures for plate-shell integrated concrete liquid storage structure (PSICLSS), shaking table tests were carried out to investigate the seismic responses of PSICLSS. The isolation performance of rubber isolation and sliding isolation bearings for PSICLSS was studied and shape memory alloy (SMA) was used to reduce the residual displacement of sliding isolation PSICLSS. The results show that the sliding isolation bearing can effectively reduce the seismic response of PSICLSS; however, there is a large residual displacement in the isolation layer. On the other hand, SMA-sliding isolation can provide a reliable recentering capability for isolating PSICLSS and does not cause amplification of structural response.

Dynamic response of shallow-buried circular composite lining tunnel with imperfect interface under SV waves

In this paper, the dynamic response of lined shallow-buried composite lining tunnel with imperfect interface in semi-infinite elastic medium under plane SV waves is studied, and the spring model is introduced to describe the imperfect interface relationship among the surrounding rock, the isolation layer, the primary support layer and main support layer. By using the wave function expansion method, the analytical solutions of displacements and stresses are presented. The interacting effects of the interface properties and the buried depth under different dimensionless frequencies are discussed. The results show that the peak values of the dynamic stress in the linings gradually shift to the upper part of the tunnel with the increase of dimensionless frequency, and the maximum dynamic stress in the linings also tends to decrease. The dynamic stress around the main and primary support layers increases when the interfaces are weakly bonded, and the effect of transverse springs is greater than that of normal springs. The tunnel with diminutive buried depth has a larger dynamic stress under the low-frequency SV waves. Reducing the stiffness in the isolation layer will lead to the increase of dynamic stress in the surrounding rock, while the dynamic stress in the main and primary support will be weakened.

Interlayer Isolation Structures Considering Soil–Structure Interaction under Long-Period Ground Motions: An Experimental Analysis

After coupling long-period seismic motions with the soil–structure interaction (SSI) effect, isolated structures can easily be resonated, and the seismic response of the structure is significantly enhanced. The SSI effect can alter the dynamic characteristics of a structure, resulting in a deviation between the assumed seismic-isolation effect of the rigid foundation and the theoretical results. To investigate the dynamic characteristics and seismic-response laws of interlayer structures considering SSI under long-term seismic motion, four types of ground motions (near-field ordinary, far-field ordinary, near-field pulse, and far-field harmonic ground motions) were selected, and two structural models (rigid-foundation and soft soil foundation interlayer seismic-isolation structure models) were established. Experiments were conducted using a combination of shaking-table tests and finite-element simulations. The results show that the use of the SSI effect caused the decrease in the acceleration response of the upper structure of both models under four types of seismic motions and increased the seismic peak ground acceleration (PGA). In addition, the weakening of the acceleration response of the upper structure under ordinary seismic motion is significant for longer periods of seismic motion. Furthermore, when considering the SSI effect, the displacement response ratio under long periods and ordinary ground motions is greater than that of rigid foundations, and the horizontal deformation of the isolation layer under long-period ground motions is greater than that under ordinary ground motions. This shows that the SSI effect weakens the interlayer shear force under ordinary seismic action more than that under long-period seismic action. When PGA increases, the interlayer shear force response of the interlayer isolation structure model with a soft soil foundation under a long-period seismic action may be smaller than that of the rigid-foundation model.

A nature-based solution to reduce soil water vertical leakage in arid sandy land

Quick water seepage in sandy soils results in a serious restriction for ecological restoration, becoming a worldwide urgent research issue in arid areas. Search for practical solutions are focused on reserving the limited rainfall into topsoil layer to meet plant water demand. Based on fieldwork, this study evaluates the blocking effects of Pisha sandstone on soil water leakage, by inserting sandstone layers in the different soil depths (10–15 cm, 20–25 cm, 30–35 cm), which act as isolation layers within the sandy soil. Results showed that the inserted Pisha sandstone layers significantly decreased the soil water infiltration rates at the different stages and cumulative infiltration. The inserted sandstone layer at the depth of 10–15 cm presented the highest permeability resistance, and its initial infiltration rate, stable infiltration rate and average infiltration rate decreased by 102.42 mm h−1, 144.30 mm h−1 and 132.79 mm h−1, respectively. Meanwhile, the soil water content in the 5–10, 20–25, and 30–35 cm soil layers increased by 2.17%, 2.20%, and 1.37%, respectively, due to the inserted Pisha sandstones. This experimental study proves that the insertion of Pisha sandstones effectively hinders the downward penetration of soil water in sandy soil. These findings provide a new alternative for an effective solution of the fast water leakage problem of sandy land.

면진층 구조를 가진 다중쉘 해저터널의 응력 저감 효과

면진층 구조를 가진 다중쉘 해저터널의 응력 저감 효과

Seismic isolation analysis and design of a plane irregular building structure in high earthquake intensity area

Taking the large commercial complex building of Changzhou Golden Eagle Plaza as the research object, this paper analyzes various parameters of typical special-shaped space structure under different isolation schemes under the conditions of earthquake protection, rare earthquake and extremely rare earthquake, compares three isolation layer design combinations of rubber isolation bearing, lead isolation bearing, rubber isolation bearing + lead isolation bearing, and studies the influence of different isolation layer arrangement schemes on the steel core and mass center of the building structure. The results show that the reasonable isolation design can obtain the reasonable arrangement pattern and rule of the plane irregular building structure in a high seismic intensity area by comparing and analyzing the arrangement schemes of different types and forms of isolation bearings in the isolation structure model.

Dynamic Response Analysis of Mega-Sub Isolated Structures under Multiaxial Earthquakes

With the use of seismic isolation techniques on mega-sub structures, several scholars have carried out research on them. However, little research has been carried out on mega-sub isolated structures under multiaxial earthquakes. There have been instances in actual engineering where the peak vertical acceleration exceeded the horizontal direction, and the vertical seismic component will also amplify the dynamic response of the structure in the horizontal direction, so in practice, it is necessary to consider the influence of the vertical component of the earthquake on the structure. To investigate the dynamic response of mega-sub isolated structures under unidirectional earthquake and coupled earthquake, this paper used numerical methods to analyze the influences of the horizontal and vertical damping ratio of the isolation layer, the horizontal and vertical frequency ratio of the main substructure, and the mass ratio of the main substructure on the acceleration and displacement of the main and substructure. The optimum parameter values are finally achieved by analytical calculations, which provide a basis for further optimization and practical design of the structure. Finally, the collision between the main and sub-structures in the mega-sub isolated structure was simulated, and the influences of the peak ground motion, main and subframe spacing, vertical seismic component, and sub-structure height on the collision force and acceleration were analyzed. It was shown that the conflict of the main and sub-structures generates instantaneous, large collision forces, which also instantaneously amplify the acceleration and base shear force response, which should be avoided in practical engineering.

Study on the seismic response of new staggered story isolated structure under different parameters

The new staggered story isolated structure is developed according to the base-isolated structure and the mid-story isolated structure. Quantitative calculation and evaluation of seismic damage are very important for structural safety. In this paper, the seismic damage evaluation of a new staggered story isolated structure is studied by numerical simulation and damage index calculation. A new staggered story isolated structure is established, and the effects of different layers and different chassis areas on the seismic response of the structure are studied. When the position of the bottom isolated layer stays the same, the upper isolated layer is set at different layers, which is set to the top of the 3rd, 6th and 9th layers. When the upper isolated layer keeps at the top of the 3rd layer, the chassis area is set at a different area, which is 26 m × 26 m, 36 m × 36 m and 46 m × 46 m. The results show that the new staggered story isolated structure has good isolated effects under the ground motion. For the structure set upper isolation layer is lower, the inter-layer shear force, inter-layer acceleration and inter-layer displacement are reduced. The energy dissipation effect of the structure improves. The core tube is less damaged and the plastic hinge is smaller. With the increase of chassis area, the isolated effect of the part above the upper isolated layer is good, while the shear force and acceleration of the part below the upper isolated layer of the structure increase, the damage at the core tube changed little and the appearance of the plastic hinge increased. Under earthquakes, with the change in position of the upper isolated layer and the area of the chassis of the new staggered story isolated structure, the displacement, tensile stress and compressive stress of the isolated bearing still meet the requirements of the standard.

Highly efficient removal of Cr(VI) from wastewater using electronegative SA/EGCG@Ti/SA/PVDF sandwich membrane

The use of green, non-toxic raw materials is of great significance to the sustainable development of the environment, among which epigallocatechin gallate (EGCG) is a renewable carbon source from plants. At present, there is a lack of research on the metal-polyphenol nanomaterials their use in water decontamination. In this study, a novel SA/EGCG@Ti/SA/PVDF (SESP) sandwich membrane was prepared to effectively solve the problems of difficult recovery of nanomaterials and the leaching of metal ions. The membrane was made by scraping SA on the surface of the PVDF substrate as the bottom protective layer, depositing EGCG@Ti NPs as the functional layer, then coating SA as the surface isolation layer, and finally cross-linking with anhydrous calcium chloride. Results showed that EGCG@Ti NPs dispersed well on the surface of the SA/PVDF basement membrane. SESP sandwich membrane had good hydrothermal and acid-base stability, and it can be applied to wastewater with multiple co-existing heavy metals (e.g., Cu, Pb, Cd, and Ni). The contact angle and pure water flux of the SESP sandwich membrane with a negatively charged surface were 14.0–15.6° and 171.40 L/m2 h, respectively. The pure water flux of the regenerated membrane after BSA pollution recovered to 98.68 L/m2 h, and the interception efficiency and the interception flux of Cr(VI) were 100 % and 72.92 L/m2 h at 40 min of interception, respectively. Additionally, the removal efficiency of Cr(VI) by SESP sandwich membrane was maintained above 83 % for simulated wastewater and 100 % for actual wastewater after five adsorption-desorption cycles. Cr(VI) and Cr(III) can be removed simultaneously with the negatively charged SESP sandwich membrane. EDS and XPS analysis showed that the removal of Cr(VI) was controlled by the Donnan effect, anion exchange, chelation/complexation, and reduction mechanism. In contrast, Cr(III) was mainly influenced by electrostatic attraction and chelation/complexation mechanisms. In conclusion, the newly prepared sandwich membrane has good application potential in treating Cr(VI) wastewater.

Constructed "sandwich" structure to obtain recyclability and high rejection rate high-flux CA@HMSN@h-BN/PDA membrane for efficient treatment of dye wastewater

It is necessary to develop a nanofiltration membrane that can remove dye molecules efficiently and is not easily polluted for the treatment of textile industry wastewater. A novel high-flux CA@HMSN@h-BN/PDA membrane with a "sandwich" structure was obtained by assembling the support layer of the Hollow mesoporous silica nanoparticles (HMSN), and the isolation layer of the h-BN/PDA on the Cellulose acetate (CA) membrane. HMSN was synthesized using ZIF-8 as a self-sacrificial template to provide improved permeability. h-BN/PDA obtained by modifying hexagonal boron nitride (h-BN) with polydopamine (PDA) brought higher hydrophilicity, rejection rate, and stability to the membrane. The study solved the problem that the membrane separation process requires sacrificing flux and recyclability for high rejection rates. CA@HMSN@h-BN/PDA membrane has a super-hydrophilic property (water contact angle of 22.5°) and high pure water flux (4419.4 L·m−2·h−1·bar−1). Meanwhile, the CA@HMSN@h-BN/PDA membrane achieves a high rejection rate (over 99.5%) due to the special "sandwich" structure. Through cycling experiments, CA@HMSN@h-BN/PDA membranes exhibit recyclability. More importantly, CA@HMSN@h-BN/PDA membranes maintain stable performance in complex environments, such as extremely acidic/alkaline or inorganic salt interference environments. Thus the CA@HMSN@h-BN/PDA membrane has the potential for future wastewater treatment.

Study on seismic safety evaluation of crossover pipeline connecting containment and turbine building in three-dimensional isolated nuclear power plant

Isolation design enhances the safety of nuclear islands during earthquakes. Magnification of isolation layer displacement increases the damage risk of the nuclear pipeline crossing the isolation gap. A simplified safety evaluation procedure for pipelines based on elbow displacement limits and damage indices was proposed. An analytical model of the nuclear elbow was first developed for unidirectional and multi-directional displacement loading. The failure point is determined based on the elbow force–displacement curve and adjusted to obtain a safe displacement limit. Subsequently, a 3DBNL model with a horizontal isolation frequency of 0.5 Hz and a vertical isolation frequency of 1.25 Hz was proposed based on the BNL model. Nonlinear time history analysis was performed to obtain the dynamic responses such as nuclear island acceleration, isolation layer displacement, and pipe relative displacement. Finally, the damage index was calculated as the ratio of the peak relative displacement to the elbow displacement limit. The damage index and the distribution interval under multi-directional seismic input were calculated separately to assess pipeline safety. The results indicate that the three-dimensional isolated nuclear island remains safe under the horizontal 0.6 g and vertical 0.4 g seismic input, while the pipeline failed under the horizontal 0.3 g and vertical 0.2 g seismic input.

A novel photodiode array structure with double-layer SiO2 isolation

A novel photodiode array structure is proposed and implemented in the paper. Based on the silicon-on-insulator substrate, the structure adopts double SiO2 layers for isolation among PN junctions. Compared with incumbent photodiode arrays with a single isolation layer, the novel design shows less leakage current, less noise, high optical response sensitivity, and better compatible integration with other devices. The dark current of this structure is less than nanoamperes (10−9 A), with the benefits of 1000 times’ less leakage current than that of other structures, and a higher sensitivity with a response speed less than 200 ns. The device is fabricated and characterized. The doping concentration and structural profile are characterized. The fabricated device is packaged with a photo light-emitting diode and the MOS device to act as the MOS relay driver. The wavelength used in the photodiode is between 500 nm–560 nm, with peak wavelength 520 nm, which can be used to drive MOS device.

Molecularly imprinted polymers-isolated AuNP-enhanced CdTe QD fluorescence sensor for selective and sensitive oxytetracycline detection in real water samples

A molecularly imprinted polymers (MIPs)-isolated AuNP-enhanced fluorescence sensor, AuNP@MIPs-CdTe QDs, was developed for highly sensitive and selective detection of oxytetracycline (OTC) in aqueous medium. The developed sensor combined the advantages of strong fluorescence signal of metal-enhanced fluorescence (MEF), high selectivity of MIPs, and stability of CdTe QDs. The MIPs shell with specific recognition served as an isolation layer to adjust the distance between AuNP and CdTe QDs to optimize the MEF system. The sensor demonstrated the detection limit as low as 5.22 nM (2.40 μg/L) for a concentration range of 0.1–3.0 μM OTC and good recovery rates of 96.0–103.0% in real water samples. In addition, high specificity recognition for OTC over its analogs was achieved with an imprinting factor of 6.10. Molecular dynamics (MD) simulation was utilized to simulate the polymerization process of MIPs and revealed H-bond formation as the mainly binding sites of APTES and OTC, and finite-difference time-domain (FDTD) analysis was employed to obtain the distribution of electromagnetic field (EM) for AuNP@MIPs-CdTe QDs. The experimental results combined with theoretical analyses not only provided a novel MIP-isolated MEF sensor with excellent detection performance for OTC but also established a theoretical basis for the development of a new generation of sensors.

免震建物に適用する過大変位抑制用性能可変オイルダンパーの開発

The developed oil damper changes the damping force passively and steplessly depended on damper displacement at low speeds of approximately 30 cm/s or less. A prototype damper with a maximum force of about 500 kN was tested and it was confirmed that the damping force changed as expected. Numerical analysis using the damper with the characteristics of the experimental results confirmed that the maximum displacement of the isolation layer was reduced by about 15% during long-period earthquakes, and that the acceleration response during moderate earthquakes was equivalent to that of a conventional seismically isolated building.

Inter-Storey Isolation Versus Base Isolation Using Friction Pendulum Systems

This study investigates the feasibility of utilizing the friction pendulum system based inter-storey isolation (FPS-I) strategy to replace the friction pendulum system base isolation (FPS-B) for high-rise structures’ vibration control against earthquakes. Both experimental verifications and computational analysis are carried out. A scaled nine-storey experimental model structure is constructed in accordance with the third generation Benchmark problem, and three aspects variant FPS with different slideway radius configurations are designed and manufactured based on the geometric similarity criterion. To assess the dynamic characteristics of FPS-B structure and FPS-I structure, four typical ground motions and four different intensities of peak ground acceleration (PGA) are considered. The findings show that FPS-I can effectively suppress the superstructure’s acceleration as well as affecting the lower substructure’s response. When the same earthquakes occur, the vibration reduction effect of FPS-I strategy is achievable between 50 and 60%, which is obviously superior to FPS-B scheme. The FPS-I technology is observed to have an even greater effectiveness on the entire structure’s vibration reduction during strong earthquakes than the traditional FPS-B technology. The basic mode as well as the higher-order mode responses of the high-rise structure can be controlled, resulting in the seismic response of the entire FPS-I structure at lower levels. The first-order mode contributes the most to the superstructure’s floor acceleration response. The location of the isolation layer changes the dynamic characteristics of the structure substantially. Finally, the finite element models for FPS-B structure and FPS-I structure are developed. It is demonstrated through the mutual comparison of experimental and numerical results that the finite element model is sufficient accurate for parametric studies. The numerical model can reproduce the dynamic characteristics of both isolation strategies with high fidelity. This research emerges the benefits of FPS with inter-storey isolation to address the issue of high-rise structures being prone to be over turned in the case of base isolation.

To Investigate Different Parameters of Economic Sliding Based Seismic Isolation System

ABSTRACT Masonry structures are frequently constructed in developing countries because of their affordability and ease of construction, even though they are vulnerable and perform poorly during earthquakes. Experimental and numerical studies were carried out to determine the optimum thickness of the isolation layer for a recently developed, low-cost seismic isolation system known as the Reinforced-Cut-Wall (RCW). The parameters of the isolation layer were optimized during the experimental and numerical investigations using hollow concrete blocks. Quasi-static cyclic tests were performed on a 1:3 reduced-scale brick masonry wall incorporating the RCW isolation scheme, validating the better performance of the proposed isolation technique.

Study on Seismic Reduction Measures of a Diaphragm Wall—Underground Structure System

In this paper, the seismic reduction and isolation measures are first proposed by setting a segmented isolation layer between the diaphragm wall and the side wall of the station structure. Although the segmented isolation layer can effectively improve the stress state of the side wall and slabs, the seismic reduction effect of the middle column is not obvious. In order to improve the overall seismic performance of the station structure, the reduction measures by combining the segmented isolation layer and new type bearing of the middle column are then proposed. At the same time of inserting the isolation layer between the diaphragm wall and the structure, the sliding bearing at the top of the column is set up to reduce the vibration. The results show that the segmented isolation layer can significantly reduce the internal force and damage at the top, bottom and side wall joints. In addition, the combined measures of segmented isolation layer and sliding bearing at the top of the column can effectively reduce the seismic damage of the middle column. The damage of the connection between the top plate, the middle plate and the middle column can be significantly decreased.

A novel approach for active and synchronous removal of fire-generated CO based on Co-La0.1 catalyst: From lab-scale to full-scale tests

CO is an invisible killer that severely threatens the safety of trapped personnel in fire disasters. The existing CO removal approaches are passive and ineffective, which could not satisfy the emergency rescue needs. An active and synchronous CO removal approach (ASCR) based on catalytic oxidation is proposed. By spraying dry powder extinguishant and catalyst powder, the isolation layer and oxidation layer are formed on the fuel surface. CO removal is achieved by both combustion suppression and CO oxidation methods. The synthesized Co-La0.1 catalyst exhibited superior catalytic activity, thermal stability, and selectivity, which met the application requirements of the ASCR approach. The results of lab-scall tests demonstrated that the CO concentration in the smoke flow decreased from 135 ppm to 0 ppm immediately once employing the ASCR approach. Full-scale tests in the confined tunnel further verified the practical application performance. With spraying 2 kg extinguishant and 0.9 kg catalyst powder, CO concentration increased merely by ∼ 20 ppm within 50 min, which was far lower than that without taking any disposal measures (∼800 ppm). This approach can effectively control the CO concentration below the safety threshold in fire disasters and is significant for emergency rescue.

Probabilistic analysis of seismic mitigation of base‐isolated structure with sliding hydromagnetic bearings based on finite element simulations

AbstractBase isolation is one of the most efficient methods for seismic mitigation of building and bridge structures in high‐intensity areas. However, the base‐isolated structure designed according to current codes based on the local seismic hazard and a few station records might not guarantee the performance of the base isolation system and ensure the safety of the structure. Carrying out a probabilistic analysis of seismic mitigation of base‐isolated structures, considering the randomness associated with earthquake ground motions, is thus necessary. To this end, the stochastic seismic response and reliability analysis of base‐isolated structures subjected to stochastic ground motions are conducted in this study, in conjunction with the probability density evolution method and the principle of equivalent extreme value event. The recently developed sliding hydromagnetic bearing is employed to constitute the base isolation layer of the base‐isolated structure. A refined finite element analysis is carried out to accurately reveal the dynamic characteristics of the base‐isolated structure. It is shown that the base‐isolated structure can be well simulated by the finite element model, which is verified through a comparative study with the results of shaking‐table tests. The base‐isolated structure gains a sound seismic mitigation compared to the base‐fixed structure in a probabilistic sense, and can ensure the safety of the structure by deploying a moderately designed base isolation system.

A New Type of Inerter with Easily Adjustable Inertance and Superior Adaptability: Crank Train Inerter

A new type of inerter, called a crank train inerter (CTI), is investigated for structural vibration isolation. The CTI consists of a crank, a linking rod, a gear-pinion box, and a flywheel that generates inertance. It has advantages of quick adjustment of inertance and strong adaptability to other disturbances. First, the inertial force provided by the CTI is linearized and expressed in a simple format; the minimum length of linking rod and crank are obtained for a CTI operating linearly under various deformed configurations. Then, the motion equation of the coupled structure-CTI system is formulated, and transmissibility is analyzed. Laboratory experiments are next carried out to verify the CTI’s mechanical property and vibration isolation performance. It is shown that the inertance of the CTI obtained in the tests agrees well with the analytical result. CTIs can significantly decrease the amplitude-frequency responses at the fundamental frequency but cannot achieve vibration isolation in a full frequency range. Finally, the seismic control effect of base-isolated buildings with and without CTI is numerically studied. An optimal design method of the CTI is proposed, and the story drift ratio and deformation of the isolation layer can be reduced simultaneously with the optimal inertance. The installation methods of CTIs for buildings are also presented.