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An energy-based identification method is proposed to investigate the seismic failure mechanism of landslides with discontinuities. The proposed method was verified by using shaking table tests on a rock slope with discontinuous structural planes. The results show that it is feasible to analyze the seismic failure mechanism of the slope by using Hilbert-Huang transform (HHT) and marginal spectrum based on seismic Hilbert energy. Earthquake energy mainly concentrating in the low-frequency components (15–17 Hz) and high-frequency components (20–40 Hz), in Hilbert energy spectrum and the marginal spectrum, respectively, suggests that they can identify the overall and local dynamic response of the slope, respectively, in combination with the Fourier spectrum analysis. In addition, the analyses of marginal spectrum can better clarify the slope dynamic damage process from the energy-based perspective, including no seismic damage stage, local damage stage, and sliding failure stage. The difference of seismic Hilbert energy between slip mass and sliding body causes their different seismic responses. The seismic failure mechanism of the landslide is identified from the energy-based perspective: the seismic Hilbert energy in 20–40 Hz mainly induces the local damage of the slope above the topmost bedding structural plane, and local failure develops first at the platform, under 0.297 g; the surface slope gradually forms a sliding body with the accumulation of local damage, and the seismic Hilbert energy in 15–17 Hz further promotes the landslide subject to 0.446 g.

This paper studies the impact of half-height infilled walls on the failure modes of frame columns through quasi-static tests of both frame models and half-height infilled wall frame models. Based on the experimental results, a seismic analysis model of reinforced concrete (RC) frame structures is established, and parametric studies are carried out to analyze the effects of masonry materials and masonry heights on the seismic performance of structures. The results show that the load-bearing capacity and stiffness of the structure are improved, while the ductility of the structure is reduced because of the existence of infilled walls. As the height of infilled walls increases, there is a notable decrease in the free height of frame columns. At a wall-to-column height ratio of 0.2, the masonry walls exert a negligible effect on the frame structure’s seismic performance. In contrast, at a ratio of 0.6, there is a transition in column failure modes from bending to shearing. When evaluated at consistent masonry heights, aerated concrete block-infilled walls demonstrate the least impact on the seismic performance of RC frame structures. Thus, in the absence of additional structural enhancements, the use of aerated concrete blocks is recommended to mitigate the negative implications of infilled walls on the seismic integrity of RC frames.

In recent years, there have been more and more engineering examples of installing giant suspended equipment (e.g., central suspended LED display) in large-span space structures; however, there are fewer studies on the seismic response and strong-seismic failure process of large-span space structures after the addition of central suspended equipment. In this paper, changes in the nodal displacements of the reticulated shell structure before and after the addition of the central suspended equipment, the proportion and distribution characteristics of the plastic shell members, and the strong seismic deformation of the reticulated shell structures are taken as indexes under the different ground motions. This paper analyses the influence characteristics of the suspended equipment on the seismic response of Kiewitt K-8 single-layer spherical reticulated shell structures and reveals the influence laws of suspended equipment with different masses on the displacement of mounting nodes and the nodes in other rings in the reticulated shell structure. Based on the plastic degree development analysis of the structures under strong ground motion, the paper analyses the failure mechanism of the reticulated shell structures with central suspended equipment and summarizes two typical failure modes. The paper analyses the influence laws and characteristics of different factors (span, rise-to-span ratio, different seismic loads and the length of suspended cables) on the seismic response of the reticulated shell structures with central suspended equipment.

The paper describes a novel Adriseismic method for expeditious assessment of seismic risk associated with unreinforced masonry buildings. The methodology was developed for the Adriseismic project of the Interreg ADRION programme, with the aim to develop and share tools for increasing cooperation and reducing seismic risk for six participating countries within the region surrounding the Adriatic and the Ionian Seas. The method is applicable to unreinforced masonry buildings characterised by three main seismic failure mechanisms, namely masonry disintegration, out-of-plane failure, and in-plane damage/failure. Depending on the input parameters for a specific structure, the assessment yields a qualitative output that consists of the masonry quality index, the index of structural response, the level of seismic risk, and the most probable collapse mechanism. Both input and output of the method are applied in the spreadsheet form. The method has so far been applied in urban areas of participating countries in the project, including Mirandola, Italy; Kaštela, Croatia; Belgrade, Serbia. In parallel, the methodology has been validated by performing a detailed seismic assessment of more than 25 buildings, and the results have been compared with the results of the proposed expeditious method. The results show a good correlation between the two methods, for example, the structural response index obtained from the expeditious method and the capacity/demand ratio obtained from the conventional assessment method.

The seismic performance of a single-layer spherical reticulated shell is the key problem to be solved in the design and analysis of this structure. In previous studies, the influences of roofing systems on the seismic performance of shells were usually ignored, resulting in large discrepancies between the results of analyses and the actual stress states of shells. In this paper, the finite element analysis method is applied to a shell with a roofing system, and the applicability of the method is proven by static loading experiments. The influences of roofing systems on the seismic performance of shells are obtained from seismic response curves, the proportions and distributions of plastic members and the failure behaviours of the shells during strong earthquakes. The mechanism of the influence of the roofing system on the seismic response of a shell is revealed by analysing the damage of purlin joints and the energy consumption of the components of the shell. The relationships that describe the influence of different parameters of reticulated shells and roofing systems on the seismic response of the shells are studied, and the results show that the roofing system can greatly change the seismic response and failure of a shell under strong earthquake conditions.

So far, little attention has been paid to the investigation on the seismic failure mechanisms of flexible concrete pile groups embedded in the layered soft soil profiles considering the material non-linearities of soil and concrete piles. The purpose of this study is to investigate seismic failure mechanism models of flexible concrete piles with varied groups in silt layered loose sand profiles under horizontal strong ground motions. Three-dimensional finite element models of the pile–soil interaction systems, which include nonlinearities of soil and concrete piles as well as coupling interactions between the piles and soil, were created for Models I, II, and III of the soil domains, encompassing 1x1, 2x2, and 3x3 flexible pile groups with diameters of 0.80 m and 1.0 m. Model I consists of a homogenous sand layer and a bedrock, Models II and III are composed of a five-layered domain with homogeneous sand and silt soil layers of different thicknesses. The linear elastic perfectly plastic constitutive model with a Mohr–Coulomb failure criterion is considered to represent the behavior of the soil layers, and the Concrete Damage Plasticity (CDP) model is used for the nonlinear behavior of the concrete piles. The interactions between the soil and the pile surfaces are modeled by defining tangential and normal contact behaviors. The models were analyzed for the scaled acceleration records of the 1999 Düzce and Kocaeli earthquakes, considering peak ground accelerations of 0.25 g, 0.50 g, and 0.75 g. The numerical results indicated that failure mechanisms of flexible concrete groups occur near the silt layers, and the silt layers have led to a significant increase in the spread area of the damaged zone and the number of damaged elements.

The residential building typology of Stone in Mud Mortar (SMM) masonry contributed significantly to the seismic losses caused by the 2015 Nepalese seismic sequence, also known as the 2015 Gorkha earthquake. SMM masonry is the most common construction type in Nepal, and notwithstanding the extensive damage, this has persisted in the post-earthquake reconstruction. This paper provides first an overview of the extent of damage and typical failure modes suffered by this typology. Some pressing issues in the ongoing post-earthquake reconstruction, such as building usability, construction quality are then discussed. The results of seismic analyses on both the pre-earthquake (PRE-SMM) and post-earthquake built (POST-SMM) typologies, using the applied element method employing a modelling strategy that accounts for the random shape of stone units, are then presented and discussed in terms of capacity curves and failure mechanisms. As per the seismic design code of Nepal, seismic performance assessment is conducted to understand the seismic design levels of these constructions. Finally, seismic fragility and vulnerability functions for both the PRE-SMM and POST-SMM typologies, considering the uncertainty in ground motions and material quality, are presented and discussed. Considering the seismic hazard in Nepal, the PRE-SMM typology is found to be highly vulnerable and seismic strengthening of these buildings is urgent. On the other hand, the POST-SMM typology has adequate seismic capacity and performs within the serviceability limit, given the quality of both the construction materials and workmanship are not compromised.

Severe cases of damages of mountain tunnels following 1995 Hyogoken-Nanbu (Japan), 1999 Chi-Chi (Taiwan), 2004 Mid-Niigata Prefecture (Japan) and 2008 Wenchuan (China) earthquakes have challenged the traditional belief of tunnel structures being seldom damaged in seismic events. These experiences are a reminder that seismic behaviour of mountain tunnels must be further studied in detail. Such investigations assume greater significance as more number of tunnels are being planned to be constructed to meet the infrastructural needs of mountainous regions all around the world. In this paper, seismic damages of mountain tunnels have been reviewed. Prominent failure patterns have been identified based on the case histories of damages. Damages in the form of cracking of tunnel lining, portal cracking, landslide induced failures, uplift of bottom pavement, failures of sidewalls, shearing failure of tunnel liner and spalling of concrete have been majorly observed. Based on the damage patterns and earthquake data, main factors leading to instabilities have been discussed. Probable failure mechanisms of mountain tunnels under seismic loading conditions have been explained. Seismic analyses of a circular lined tunnel in blocky rock mass have been carried out through discrete element based approach. The significant role of different seismic parameters like frequency, peak ground acceleration has been identified. Moreover, effect of tunnel depth on the seismic response of tunnels has been investigated. It is believed that the present study will help in advancing the present state of understanding with regard to the behavior of tunnels under seismic conditions.

This study aims to investigate the dynamic response and failure mechanism of bedding rock slopes in earthquake-prone areas with high intensity. Taking the Xinmo landslide as a case study, a shaking table model test was conducted. To overcome the limitations of previous single response feature parameters such as PGA, which cannot fully explain the dynamic characteristics of slopes under seismic excitation, this study approached the analysis from the perspective of energy. The influence of seismic wave types, frequencies, and amplitudes on the dynamic response was researched. The nonlinear dynamic response mechanism was explored. The influence of damage on dynamic response was discussed. A damage identification method was proposed, clarifying the progressive damage deformation process of the slope. Test results show that it is feasible to reveal the dynamic response laws and failure mechanism of the slope from the perspective of energy. Damage affects the dynamic response of the slope by reducing the natural frequency of the model slope, changing the energy transmission coefficient of the seismic wave, and increasing the dissipation energy of the seismic wave. The change pattern of the energy transmission coefficient can effectively identify the damage of the slope. The bedding rock slope fails in a tension-shear-sliding mode under seismic excitation. The difference in dynamic response caused by seismic energy difference is the main reason for damage deformation of the bedding rock slope, and the connection of shear-tensile cracks along the bedding structure plane is the direct cause of slope instability and sliding.

Due to complex geological structures and strong crustal activity, geological disasters occur frequently in the upper reaches of the Yalong River, Southwest China. Toppling failure on anti-dip rock slopes is a common phenomenon; in particular, after the Wenchuan earthquake in 2008, numerous landslides caused by toppling deformation occurred in reservoir areas, seriously threatening the construction and operation of large-scale water conservancy projects and hydropower projects. Taking three typical toppling slopes in the basin as research objects, the dynamic behaviour, failure evolution, and failure plane location of toppling failure under seismic waves were investigated by shaking table tests and UDEC simulations. The test results indicated that slope angle and stratum dip angle were both inversely proportional to the stability of the slope in the tested ranges. The failure evolution of toppling on anti-dip rock slopes could be divided into four stages: (1) the development stage of tensile cracks in the strata; (2) the formative stage of tensile cracks at the crest of the slope; (3) the formative stage of toppling zones; and (4) the failure stage. Two equations were proposed to reveal the relationships between the surface peak ground acceleration and the horizontal depth of the failure plane and displacement of the slope surface. The propagation and coalescence of discontinuous cross joint in the slope and the entire failure evolution simulated by the UDEC damage model agreed well with the shaking table test results.