Earthquake Conditions Research Articles

Improving Railway Alignment Selection in Mountainous Areas with Complex Vegetation: A Multisource Data Landslide Identification Approach for Assisted Decision-Making Research

In order to provide important assistance for the scientific and effective route selection of future planned railways in the research area and to quickly and accurately identify the distribution range of landslides, thereby proactively mitigating the impact of geological hazards on railways under earthquake conditions, this study aims to shift the risk threshold for geological hazards and provide a scientific basis for the accurate planning and route selection of railways in mountainous areas. Jiuzhaigou was selected as the research area and postearthquake surface deformation information in the study area was obtained through Sentinel-1 satellite radar data. Based on Sentinel-2 optical remote sensing imagery, the changes in vegetation indices in the study area before and after the earthquake were analyzed in depth. The concept of vegetation index difference was proposed as a characteristic parameter for landslide information interpretation and a method combining surface deformation information was developed for landslide information interpretation. According to this method, the study area experienced a deformation subsidence of up to 14.93 cm under the influence of the earthquake, with some areas experiencing an uplift of approximately 6.0 cm. The vegetation index difference in the research area ranged from −1.83502 to 1.45366. The total number of landslides extracted is 12.034 km2 and 164 landslide points are marked, with an overall recognition accuracy of 92.6% and a Kappa coefficient of 0.876. The research results provide new research ideas for landslide information interpretation and can be used to assist in the decision-making of mountain railroad alignment options.

Modified Andersen and Modified ICOLD (DOISP-2) Methods of Risk Score for Dams in West Region of Indonesia

Risk assessment for the dams in West Java Province with a method of Modified Andersen and Modified ICOLD (DOISP-2) have been done; the assessment is part of the activities of Dam Operation Improvement Safety Project-2 (DOISP-2) at Central Project Implementation Unit (CPIU), Ministry of Public Works and Housing. Dams were studied to analyse the risks of the deficiency of the structure due to the load under normal operating conditions, flood conditions, and earthquake conditions. This article summarizes the risk assessment process, assessment results, conclusions and recommendations for both risk index methods. The document also includes an assessment of the risk assessment process and policy recommendations for the operation and maintenance of dams. The results are risk rankings between the two methods give different sequences; this is due to differences in the risk assessment approach of both methods. Modified Andersen focused on structural deficiencies, especially visually, and modification ICOLD Method (DOISP-2) focused on design flaws and risks downstream of the dam. Although both methods have different approaches, both methods can be used in risk analysis of the dam’s adjusted purposes of risk index assessment.

Temporary stress regime reversal immediately after the complete release of the localized compressive stress by the 2021 Luxian Ms 6.0 earthquake, Sichuan Basin

Aftershocks can provide fundamental information of the seismogenic structure and the stress condition of the source region to reveal the seismogenic mechanism of earthquakes without clear surface rupture. On 16 September 2021, a destructive Ms 6.0 earthquake broke the seismic quiescence of the Luxian county in the inner Sichuan Basin, China. Here, we explore the seismogenic structure and the postseismic stress condition of the Luxian earthquake through characterizing sedimentary faults in the spatiotemporal distribution of aftershocks, through the focal mechanism solutions and further stress inversion, and through the coseismic rupture model based on synthetic aperture radar interferometry (InSAR) data. Our results show that aftershocks are concentrated at two clusters in the broad Yujiasi syncline. Seismicity of the northern cluster reveals that the main shock ruptured an east-southeast striking fault with a dip angle of ∼ 45° to the southwest (F0), and activated a gently dipping (∼ 18°) fault (F1) below F0 and a nearly vertical shallow fault (F2) on the northern side of F0. These three faults outline the edges of a thrust wedge in the sedimentary cover. The northern cluster occurred on a conjugate fault system within which steep faults with different dipping direction interlaced downward forming ‘V’ shapes. The main reverse rupture on the east-southeast striking F0 fault is inconsistent with the background northwest-southeast tectonic stress field. Combined with the morphology of anticlines, we suggest that the main shock was resulted from the localized NE-SW compressive stress concentration due to the inhomogeneous deformation of the sedimentary cover. Aftershocks with magnitude ≥ 2.0 are characterized by the dominant normal slip. Coulomb stress change (ΔCFS) results show that normal slip is enhanced by the main rupture. However, the amplitude of ΔCFS (a few bars) is not large enough to reverse the dominant slip direction of faults. Postseismic stress inversion results show a temporary stress regime reversal from the nearly north-south subhorizontal compressive stress regime before the main shock to the normal slip favored stress regime with a subvertical maximum principal stress (σ1). We suggest that the Luxian Ms 6.0 earthquake as an unusual event completely released the localized horizontal compressive stress and hence caused a temporary reversal of the localized stress regime.

Pseudo-dynamic analysis of a 3D tunnel face in inclined weak strata

A new discretization technique is proposed for a three-dimensional (3D) tunnel face in weak strata with a random position in space. This method limits the angle, height, and thickness of the strata on the tunnel face. The original whole piece of soil is separated by a series of parallel planes, and two parallel planes are used as a stratum. Each radial discrete plane is separated when it passes through the strata, and the change in the soil properties of discrete points on the truncated plane is considered separately inside the strata. Considering the spatial and temporal characteristics of seismic waves, a pseudo-dynamic analysis of the tunnel face is carried out. The tunnel face active damage types under earthquake conditions are quantitatively analyzed, and the corresponding support pressure design diagrams are given for the case without weak strata. For the case containing weak strata, the presence of weak strata can have adverse effects on the face. The failure mechanism of the weak strata is given by the discretization method. For different friction angles, the presence of the weak strata changes the friction angles of the soils. For the thickness, location and angle of the weak strata, the variation in the support pressure is given in this paper. To more intuitively depict the change in the failure mechanism in the presence of weak strata, the change in the failure mechanism under different thicknesses and weaknesses of weak strata is plotted.

Random analysis of train-bridge coupled system under non-uniform ground motion

The increasing prevalence of simply supported bridges in high-speed railway (HSR) lines has raised concerns about the safety of trains crossing these bridges during an earthquake. As these bridges are typically continuous and long, it is essential to consider the effects of traveling seismic waves on the random vibration of the train-bridge coupled (TBC) system. To address this issue, the new point estimate method (NPEM) is used to analyze the dynamic response and parametric sensitivity of a three-dimensional TBC system subjected to non-uniform ground motion with multiple random parameters. The motion equations of the TBC system are derived using bridge seismic theory under multi-support excitations. The analysis incorporates random variables such as the damping ratio, density, Young’s modulus, and seismic magnitude to capture the influence of traveling seismic waves on the random vibration of the TBC system. Simulation results show that the traveling seismic wave effect can cause changes in the first vibration frequencies of the train and bridge, potentially leading to the first few frequencies reordering. Additionally, considering the traveling wave effect will make the TBC system’s response less apparent than without considering the traveling wave effect. The uncertainty of bridge and seismic parameters can seriously affect the train’s running safety. The sensitivity of the bridge density and seismic magnitude is particularly prominent for bridge responses when the traveling seismic waves effect is strong. This methodology can be used for random and sensitivity analysis of a train running over a long bridge under non-uniform earthquake conditions. Overall, the NPEM can provide valuable insights into the dynamic behavior and safety of TBC systems, enabling more effective design and maintenance of HSR bridges.

Design of Earthquake Warning Alarm Using Accelerometer Sensor Based on Internet of Things

Earthquake is natural event due to release of energy suddenly from within that creates seismic waves. The vibrations are usually caused by movement of earth's plates. It cannot be predicted when they are coming. Therefore, need to build an early warning system. It is for anticipation of save the community when an earthquake occurs. It provides solutions to minimize the impact of earthquake events. This system uses accelerometer sensor and arduino nano as a main controller and it is accompanied by Blynk application. This works for sent notification via smartphone. This tool has been successfully designed with manual testing to be able to see the sensitivity of earthquake sensor made. Accelerometer sensor works is using Tilt Method. Accelerometer sensor will tilt on surface as parable of earthquake. Accelerometer sensor will send vibration signal when earthquake occurs. Signal processing is done by Arduino nano as the main controller in system. If the signal is received by sensor then value of earthquake will be displayed on LCD screen. Status of earthquake was separated into 4 levels such as standby, alert, dangerous, dangerous and dangerous. After earthquake value appears on the LCD screen and the status is known then buzzer will sound. It indicates that the earthquake warning alarm is properly functioning. Next, NodeMCU also sends information to Blynk application, which is used as a notification and monitoring of earthquake conditions. Buzzer will sound as a warning alarm to notify peoples to save themselves. This sensor has three output coordinate points, namely X, Y, Z, which have analog values ​​on Arduino Nano. This analog value can be converted into Richter Scale. Based on experimental results, an analog value is 100 – 400.

Numerical investigation of post-earthquake rainfall-induced slope instability considering strain-softening effect of soils

Although rainfall and earthquake have been widely recognized as the two most important factors for landslide, the failure mechanisms of a soil slope under the two natural disaster factors are totally different, thus it is still challenging to answer what will be the response of the soil slope under some extreme conditions of the individual factor or the combination ones. In this paper, we present a novel numerical investigation of the combined effect of earthquake and rainfall on slope instability. The deformation responses of a soil slope under different conditions of earthquake, rainfall and post-earthquake rainfall are analyzed using FLAC3D with user-defined subroutines for defining the strain-softening behavior of the soil. The Mualem's seepage model is adopted for rainfall infiltration and slope deformation analysis. The numerical results indicate that the strain-softening behavior of the soil will significantly influence the seismic slope displacement caused by the earthquake ground motion. Considering extreme cases of rainfall after a short period of earthquake-induced slope deformation with local strain-softening, the combined effects take different forms of accumulating the ultimate slope displacement. The post-earthquake rainfall infiltration will make the seismically disturbed slope to be deteriorated further of the shear strength, and ultimately a landslide develops over time. It is anticipated that the findings from this study could provide reference value for understanding the landslide mechanism of soil slopes under the combined effect of earthquake and post-earthquake rainfall in order to plan for rationale disaster prevention measurements.

Structural Design and Analysis of a Super-High Building in Nanjing, China

This study analyzes a high-rise building with B-level height (i.e., a total height of 146.5 m) and a shear wall structure. Since the project contains many plane irregularities (including 1a torsional irregularity, 1b eccentric arrangement, and 2a plane convex irregularity), it should be treated as a super high-rise building. This study introduces the main characteristics and overrun conditions of the project and describes the structural design of the foundation and the basement, upper structural layout, force conditions under frequent, fortified, and rare earthquake actions, and structural performance-based objectives in detail. The following measures can be adopted to address the overrun problem. First, the floor at the thin waist of the structure was thickened to 150 mm and reinforced in the bilayer and bidirectional patterns, with a reinforcement ratio of no less than 0.25%. The damage condition on the floors under a great earthquake was analyzed. The vertical components at the waist were reinforced to constrain the extension of the edge components toward the top. Second, the structure’s peripheral stiffness was strengthened to enhance the anti-torsional performance and minimize the adverse effects on torsional irregularities. Third, using two software programs, the performance-based envelope design under medium earthquake action and dynamic elastoplastic analysis under great earthquake action were analyzed to ensure structural safety. Fourth, the edge components were constrained for the shear wall columns with axial-to-compressive stress strength ratios exceeding 0.3. For the overall structure and critical parts, force conditions under frequent, fortified, and rare earthquake conditions were calculated and examined with the SATWE, MIDAS GEN, and SAUSAGE software packages. The calculation results revealed that the structure shows favorable anti-seismic performance, with an overall anti-seismic C-level and a safe and reliable structure. The structural design method introduced in this article can promote the sustainable development of structural design.

Analysis of sheet pile position influence in countermeasure to landslide at the cutting slope in infrastructure project

Slope is a land surface that has a certain angle of inclination in the horizontal plane. The existence of the slope of the land causes the forces that push so that the soil at a higher elevation to move. If the movement is not resisted, the slope may collapse. The purpose of this analysis is to determine the effect of sheet piles where the position and depth of sheet piles, ground water level and earthquake factors on the stability of excavation slopes in infrastructure project of Karawang New Industry City (KNIC) LG area. For this reason, slope stability analysis was carried out using a finite element-based analysis program where the output sought was sheet pile displacement and safety factor. The data used in this study are N-SPT data and W-325 sheet pile property data. The sheet pile position is varied into 6 variations, at positions 2, 4, 6, 8, 10, and 12. The sheet pile length is varied from 4 meters to 12 meters and the slope water level is varied into 6 conditions, namely conditions without ground water, ground water level 5 meters, 4 meters, 3 meters, 2 meters and 1 meter. From this analysis it was found that the position of sheet pile affects the value of the safety factor and the critical depth of sheet piles. The analysis is continued by analyzing the earthquake load at a water level of 1 meter. From this analysis, all positions and depths are not able to withstand earthquake loads, so other alternatives are needed. Considering the earthquake load and the resulting landslide pattern, the slopes require additional reinforcement where sheet piles will be installed in position 10 with a length of 12 meters and at 1 meter from the roadside at a depth of 1 meter with a length of 11 meters. With this reinforcement, the safety factor value is 1.675 in static conditions and 1.131 in earthquake conditions so that sheet piles can meet the minimum limit requirements i.e., 1.5 in static conditions and 1.0 in earthquake conditions.

Shaking table test for dimension stone cladding with dowel pin connection

Under earthquake loads, economic loss and threatening human casualties can occur owing to fallouts of exterior cladding stones in buildings. In this study, a shaking table test was performed to investigate the seismic capacity and demand of stone cladding with pin connections. Two reinforced concrete structures attached to dowel-pinned stone panels were tested under ground motion to simulate actual earthquake conditions. A total of 19 combinations of stone panels were used to address the major parameters for the construction of dimension stone claddings in practice. The test results showed that in most of the specimens, pull-out failure of the pin connection occurred prior to the stone breakout failure, resulting in stone fallout. The seismic demand for stone panels without an insulator was significantly less than the seismic capacity, showing a capacity-to-demand ratio of 4.00–12.60. However, the capacity-to-demand ratio was 0.37–2.66 in the case of stone panel details with an insulator but without a supporter, indicating that special care is necessary for those details. Based on the test results, design and specification recommendations were proposed for stone panels with dowel pin connections.

Study on structural damage evolution of excavated slope subjected to earthquake and rainfall using electrical resistivity measurement

Earthquake and rainfall are two major factors contributing to the slope failures. To examine the evolution of slope structural damage and the failure mechanism during the shaking and rainfall process, a model test of excavated slope subjected to earthquake and rainfall has been performed. The evolution of structural damage within the slope is considered as the changing process of porosity and crack development. The unique relation between of porosity and resistivity of unsaturated soil is utilized to reveal the spatial-temporal variation of slope structural damage by electrical resistivity measurement method. The testing results show that the shaking induced cracks appear on the surface of upper soil layer at the mid-height of slope model, and the structural damage could be both accumulated on the surface and inside the slope under seismic motion. The damaged area provides preference infiltration path for rainwater flow in the following raining process, resulting in the rapid increase of water content of slope interior. The sliding body extends and develops upwards to the slope crest under rainfall condition. The failure patten suggested by the structural damage parameter is verified by the dynamic response of slope model. The structural damage parameter using resistivity is able to show the spatial-temporal evolution of structural damage inside the slope quantitatively, and reflect the porosity change of soil under continuous earthquake and rainfall conditions. The evolution of structural damage reveals that the dynamic failure mode of excavated slope under earthquake and rainfall is the upwards-developed retrogressive sliding of upper soil layer. The evaluating method using resistivity measurement is particularly promising for field test of slope where it can be used to monitor the structural damage change of soil mass subjected to complex environment conditions.

Analisis Stabilitas Lereng Bendungan Terhadap Beban Gempa sebagai Upaya Pengurangan Bencana (Studi Kasus: Bendungan Jlantah)

Indonesia is a country that has quite high seismic activity and is prone to earthquake hazards, so the construction of embankment dams in Indonesia needs to pay attention to stability against collapse due to soil mass and earthquake loads. Jlantah dam is located in Karanganyar, Central Java. This dam is planned for irrigation needs of 1493 hectares and raw water of 150 liters/second. This study aims to determine the safety factor (Fs) on the Jlantah Dam body. The method used is a quantitative data analysis method, the calculation of the earthquake coefficient corrected by OBE and MDE, carried out with the help of a computer program, namely GeoStudio 2012. Meanwhile, if the earthquake coefficient is known not to be Fs 1.5. The method used is based on references from KP 02-Planning Criteria for Main Building Section and KP 06-Planning Criteria for Parameters Section, and Pd T-14-2004-A. The terms (Fs 1,2) which are used as the theoretical basis are quoted from the theory of Prof. Hoek (1981) stated that by knowing the earthquake coefficient, Fs 1.2 can be used, while if the earthquake coefficient is not known Fs 1.5 Analysis of Earthquake Backfill Type Dam Stability. From the results of the study, it was found that at the time of maximum water and the earthquake for the road dam body was declared from a good structural failure. The results of the bottom study on MDE earthquake conditions from the maximum water level obtained Fk > 1.0 Fk minimum, the maximum water level obtained Fk > 1, 2 Fk minimum with OBE earthquake conditions.

TRAINING ON THE USE OF EDUPOINT: MINI DRIVE LEARNING RESOURCES FOR DISASTER EMERGENCY SCHOOLS IN PADALUYU VILLAGE, CUGENANG SUB-DISTRICT, CIANJUR REGENCY

The results of initial observations, especially in Padaluyu Village, Cugenang District, obtained data that there were 27 RTs spread across Padaluyu Village. The condition of 8 RTs experienced very severe damage (all houses collapsed) 19 RTs experienced severe and moderate damage. There are elementary schools in Cugenang District that need assistance related to the implementation of learning, especially the availability of learning resources, namely SDN Padamamur, SDN Padaluyu, and SDN Kembang Manis 2. The purpose of implementing this PKM is to overcome problems experienced by partners related to obstacles in the learning process that occur due to the earthquake. With the damage to some school rooms, learning must be diverted elsewhere. Therefore the development of Edupoint is considered appropriate to overcome this problem. EduPoint is a learning tool designed as a medium for providing access to mobile learning that can be accessed via various devices such as laptops, computers, smartphones and tablets in a local network so that it does not require quota or unstable signals due to earthquake conditions. This tool is designed so that students can study anywhere without having to take place in the classroom. The design concept of this tool is intended to accommodate the learning process so that it can continue under any conditions so that it can be easily moved wherever learning conditions take place (portable). After completing the development of the tool, training is needed for teachers to use it. The training activity on using EduPoint: Mini Drive Learning Resources for Disaster Emergency Schools ran smoothly. The response from the partners and training participants was very good thanks to the good cooperation between the University of Ibn Khaldun Bogor and the partners involved. The results of the training show that teachers are able to properly use the learning resources accessed through EduPoint.

Influence of Slag-Based Geopolymer Concrete on the Seismic Behavior of Exterior Beam Column Joints

In reinforced concrete (RC) constructions, the beam-column junctions are very sensitive to lateral and vertical loads. In the event of unforeseen earthquake and wind loads, this insufficient joint performance can lead to the failure of the entire structure. Cement industries emit a large amount of greenhouse gases during production, thus contributing to global warming. The nature of cement concrete is fragile. Cement output must be reduced in order to ensure environmental sustainability. Geopolymer concrete (GC), which is a green and low-carbon material, can be used in beam-column joints. M30 grade BBGC was developed and employed in the current study. Alkaline liquids are produced when sodium silicate and sodium hydroxide are mixed at room temperature. The alkaline liquid to fly ash ratio was fixed at 0.5, and the concentration of NaOH was fixed at 8 M. The mechanical properties of the Binary Blended Geopolymer concrete (BBGC), containing fly ash and GGBS, at proportions ranging from 0% to 100%, were investigated. This study was further expanded to examine the behavior of two groups of binary blended geopolymer concrete (BBGC) exterior beam-column joints, with cross sections of 230 mm × 120 mm and 170 mm × 120 mm. The column heights and lengths were both 600 mm under reverse cyclic loads in order to simulate earthquake conditions. The failure mechanism, ductility, energy absorption capacity, initial crack load, ultimate load carrying capacity, and structural performance was evaluated. The test findings showed that BBGC with 20% fly ash and 80% GGBS had the highest compressive strength and split tensile strength. When compared with other beam column joints, those containing 20% fly ash and 80% GGBS performed better under cyclic loading. The test findings imply that GGBS essentially enhances the joint performance of BBGC. The microstructural SEM and EDS studies revealed the reasons behind the improvement in strength of the GGBS fly ash-based Geopolymer concrete.

Temperature Field and Stress Analysis of the Heavy-Concrete Transfer-Purge Chamber of the Nuclear Power Plant.

A transfer-purge chamber (TPC) is a double-steel-plate, heavy-concrete, curved-surface composite structure composed of steel plates, heavy concrete, and shear connectors. It is an important facility in the external refueling system of a nuclear power plant (NPP), providing a safe and reliable biological shielding space for reactor refueling operations. Temperature load is one of the most important factors that must be considered in the design of NPP structures. The temperature loads experienced by the TPC during its life cycle include those encountered in both normal and abnormal operation, which are distinct. In this study, we investigated the steady state and transient-state temperature fields and stresses of a TPC structure under normal operation and after 48 h of abnormal operation, respectively, which were calculated using Abaqus finite element software and the directly coupled method. During normal operation, the temperature field of the structure shows relatively uniform changes, and the temperature gradient of the internal concrete in the direction of its thickness has a constant value of 0.245 °C/cm. At the junction between the transfer and purge sub-chambers of the TPC, under the influence of wall curvature and deformation constraints, the maximum tensile strain of heavy concrete is 8.84 × 10-3, the maximum compressive strain is 2.04 × 10-3, the peak stress of the steel plate is 98.305 MPa, and the peak stress of the stud is 306.725 MPa. After 48 h of abnormal operation, the temperatures of the inner surface of the heavy concrete of the wall, the inner steel plate of the wall, the outer surface of the heavy concrete of the wall, and the inner steel plate of the wall increased by 8.12, 8.11, 0.31, and 0.30 °C, respectively. The tensile strain of the heavy concrete of the wall increased significantly by 52.64%, and the compressive strain of the concrete increased by 67.33%, whereas the stresses of the studs and steel plates increased by only 1.57% and 6.79%, respectively. These results show that the change in the temperature field greatly influences the stress and strain on the TPC structure. As measures for mitigating the development of this unfavorable situation of temperature stress concentration, the temperature operating range should be rationally controlled or the junction structure between the transfer and purge sub-chambers of the TPC optimized accordingly. The results of our study can provide basic data for a dynamic analysis of the TPC under conditions of combined earthquake and temperature loads.

Application of Seismic Fragility of Buried Piping Systems with Bellows Expansion Joints

Bellows expansion joints are known to have a large displacement capacity and can thus be potentially used to improve the seismic performance of buried piping systems. However, there are no guidelines on the installation of bellows expansion joints for the seismic performance improvement of buried piping systems. Furthermore, there are very few studies on the seismic performance of buried piping systems with bellows expansion joints. In this study, therefore, we performed seismic fragility analysis according to the installation conditions to obtain basic data for the installation guidelines of bellows expansion joints. Therefore, in this study, an experimental test was performed on bellows expansion joints considering the characteristics of earthquake loading conditions, and a 3D finite element (FE) model using the ABAQUS platform was developed and validated based on the experimental results. This model was verified by comparing the force-displacement relationship and energy dissipation. Leakage occurred at a displacement of 113.6 mm in the experiment, and the FE analysis result was also applied up to the same displacement. In the case of energy dissipation, an error between the FE model and experimental result was determined not to be significant. However, the appearance of such physical performance errors is due to the manufacturing errors resulting from the bellows forming process and the variability of material properties. Finally, seismic fragility analysis of buried pipeline systems with bellows expansion joints was performed. In addition, the following cases were used for analysis according to whether bellows were applied or not: (1) without a bellows expansion joints; (2) with a single bellows expansion joint; and (3) with two bellows expansion joints. In conclusion, it was found that the seismic performance of the buried pipeline system was improved when bellows were applied. However, the effect of the seismic fragility curve according to the increase in the number of bellows was insignificant.

Analysis of irregular multistorey buildings with and without floating columns under seismic loading

Floating column is a vertical structural member that rests on the beam. Floating column is advantageous to provide large open space in a building, but it is disadvantageous in earthquake conditions. On the other hand, by the advancements in civil engineering knowledge, architects try to adopt irregular shapes of buildings. Providing floating columns in irregular buildings is a challenging issue for civil engineers they should deal with. That’s why study of application of floating column in irregular buildings is one of the important topics in modern civil engineering. This study focuses on analysing the seismic behaviour of G + 10 irregular buildings considering floating columns and without floating columns to compare with a regular building. The building models are analysed in ETABS V19 software, then analytical findings are explained in terms of (maximum storey drift, maximum storey displacement, and torsional irregularity). From the study it is found that providing floating columns in irregular buildings increase storey drift and storey displacement significantly. Similarly, the torsion increases in buildings when the floating columns are not provided symmetrically.

The Seismic Performance and Global Collapse Resistance Capacity of Infilled Reinforced Concrete Frames Considering the Axial–Shear–Bending Interaction of Columns

This paper presents a mechanism and method for simulating the axial–shear–bending interaction of a reinforced concrete (RC) column. The three-dimensional model of a multi-story infilled RC frame was modeled using the OpenSees software. Static pushover and nonlinear dynamic analyses under fortification and rare earthquakes were conducted using the model. Finally, based on the incremental dynamic analyses of 22 suites of ground-motion records, the global collapse resistance capacity of the infilled RC frame was evaluated using the evaluation method of a normal distribution. The analytical results show that the axial–shear–bending interaction is a key factor that affects the seismic response of infilled RC frames. Under the fortification earthquake condition, no obvious damage to physical structures was evident; the influence was relatively minor. However, under the condition of a rare earthquake, severe damage to physical structures was evident, resulting in the underestimation of the lateral inter-story drift ratio, while the degradation rates of the load capacity and global collapse resistance capacities for the infilled concrete frames were highly overestimated when the axial–shear–bending interaction was not considered.

Experimental Study of Frame-Supported Shear Wall Structure of High-Rise Buildings with Transfer Slab in Metro Depot

Taking the frame-supported shear wall structure of a 102.1 m high metro depot as the test object, the structure has obvious vertical irregularity, and a quasi-static test was carried out on the structural model with the scale of 1/5. The damage development and strain of the structure were observed by applying displacement loads under different seismic actions, and the experimental phenomena and measured data were analyzed. The results show that the safety performance of the structure meets the seismic requirements of the MCE (Maximum considered earthquake) condition. Under the action of load, a reasonable damage mechanism is formed in which the components above the transfer story crack first and those below the transfer story crack later, which is in line with the design concept of “the performance objective of the bottom frame structure is higher than that of the upper shear wall structure”. The transfer plate is mainly subjected to shear deformation, the possible shear failure of the transfer plate should be avoided by reasonable design. Due to the large height difference between the first floor and the second floor, the structure may be adversely affected, so it is necessary to make the yielding floor appear in the bottom strengthening part above the transfer story. Under the SLE (Service level earthquake) and DBE (Design based earthquake) conditions, the bottom frame of the structure is mainly subjected to elastic deformation. Under the MCE (Maximum considered earthquake) condition, the bottom frame of the structure causes a lot of damage, increases energy consumption and decreases stiffness, which further proves that “the performance goal of the bottom frame structure is higher than that of the upper shear wall structure”.

Stability analysis before and after support of a multi-stage structural surfaces landslide mass

A typical multi-stage structural surfaces landslide mass located in Sichuan Province, SW China, is used as the research object. Based on the site survey and related data collection and analysis, the topography, geomorphology, stratigraphic lithology and geological structure of the study area were identified, and the engineering geological conditions and signs of deformation and damage of the landslide mass were analysed and studied. The stability characteristics of four levels of structural slip surfaces on the main section of the landslide mass under natural, rainstorm and earthquake conditions were comprehensively analysed using the transfer coefficient method and Geo5 geotechnical analysis software. The results show that the stability of the four slip surfaces ( ab , bc , ad and ae ) of the landslide mass is basically stable, basically stable, stable and stable under natural conditions; basically stable, less stable, stable and stable under earthquake conditions; and less stable, unstable, stable and stable under rainstorm conditions. It is found that the stability of the two shallow slip surfaces ( ab and bc ) is relatively poor. An anchor support design was chosen to reinforce the landslide mass, and the stability of the supported landslide mass was verified by Geo5 software.