Influence of Various Earth-Retaining Walls on the Dynamic Response Comparison Based on 3D Modeling

The present work aims to assess earthquake-induced earth-retaining(ER)wall displacement.This study is on the dynamics analysis of various earth-retaining wall designs in hollow precast concrete panels,reinforcement concrete facing panels,and gravity-type earth-retaining walls.The finite element(FE)simulations utilized a 3D plane strain condition to model full-scale ER walls and numerous nonlinear dynamics analyses.The seismic performance of differentmodels,which includes reinforcement concrete panels and gravity-type and hollowprecast concrete ER walls,was simulated and examined using the FE approach.It also displays comparative studies such as stress distribution,deflection of the wall,acceleration across the wall height,lateral wall displacement,lateral wall pressure,and backfill plastic strain.Three components of the created ER walls were found throughout this research procedure.One is a granular reinforcement backfill,while the other is a wall-facing panel and base foundation.The dynamic response effects of varied earth-retaining walls have also been studied.It was discovered that the facing panel of the model significantly impacts the earthquake-induced displacement of ER walls.The proposed analytical model’s validity has been evaluated and compared with the reinforcement concrete facing panels,gravity-type ER wall,scientifically available data,and American Association of State Highway and Transportation Officials(AASHTO)guidelines results based on FE simulation.The results of the observations indicate that the hollow prefabricated concrete ER wall is the most feasible option due to its lower displacement and high-stress distribution compared to the two types.The methodology and results of this study establish standards for future analogous investigations and professionals,particularly in light of the increasing computational capabilities of desktop computers.

Recent progress of seismic research on tall buildings in China Mainland

As a result of rapid economic growth and urbanization in the past two decades,many tall buildings have been constructed in China Mainland,offering researchers and practitioners an excellent opportunity for research and practice in the field of structural engineering. This paper reviews progress by researchers throughout China Mainland on the seismic research of tall buildings,focusing on three major topics that impact the seismic performance of tall buildings. These are:(1) new types of steel-concrete composite structural members such as steel-concrete composite shear walls and columns,(2) earthquake resilient shear wall structures such as shear walls with replaceable structural components,self-centering shear walls and rocking walls,and(3) performance-based seismic design,including seismic performance index,performance level and design method. The paper concludes by presenting future research needs and directions in this field.

A Dynamic-Bayesian-Networks-Based Resilience Assessment Approach of Structure Systems: Subsea Oil and Gas Pipelines as A Case Study

Under unanticipated natural disasters, any failure of structure components may cause the crash of an entire structure system. Resilience is an important metric for the structure system. Although many resilience metrics and assessment approaches are proposed for engineering system, they are not suitable for complex structure systems, since the failure mechanisms of them are different under the influences of natural disasters. This paper proposes a novel resilience assessment metric for structure system from a macroscopic perspective, named structure resilience, and develops a corresponding assessment approach based on remaining useful life of key components. Dynamic Bayesian networks(DBNs) and Markov are applied to establish the resilience assessment model. In the degradation process, natural degradation and accelerated degradation are modelled by using Bayesian networks, and then coupled by using DBNs. In the recovery process, the model is established by combining Markov and DBNs. Subsea oil and gas pipelines are adopted to demonstrate the application of the proposed structure metric and assessment approach.

Fault Tolerant Suffix Trees

Classical algorithms and data structures assume that the underlying memory is reliable,and the data remain safe during or after processing.However,the assumption is perilous as several studies have shown that large and inexpensive memories are vulnerable to bit flips.Thus,the correctness of output of a classical algorithm can be threatened by a few memory faults.Fault tolerant data structures and resilient algorithms are developed to tolerate a limited number of faults and provide a correct output based on the uncorrupted part of the data.Suffix tree is one of the important data structures that has widespread applications including substring search,super string problem and data compression.The fault tolerant version of the suffix tree presented in the literature uses complex techniques of encodable and decodable error-correcting codes,blocked data structures and fault-resistant tries.In this work,we use the natural approach of data replication to develop a fault tolerant suffix tree based on the faulty memory random access machine model.The proposed data structure stores copies of the indices to sustain memory faults injected by an adversary.We develop a resilient version of the Ukkonen’s algorithm for constructing the fault tolerant suffix tree and derive an upper bound on the number of corrupt suffixes.

Seismic design and analysis of a high-rise self-centering wallbuilding:Case study

Post-tensioning self-centering walls are a well-developed and resilient technology.However,despite extensive research,the application of this technology has previously been limited to low-rise buildings.A ten-story selfcentering wall building has now been designed and constructed using the state-of-art design methodologies and construction detailing,as described in this paper.The building is designed in accordance with direct displacement-based design methodology,with modification of seismic demand due to relevant issues including higher-mode effects,second order effects,torsional effects,and flexural deformation of wall panels.Wall sections are designed with external energydissipating devices of steel dampers,and seismic performance of such designed self-centering walls is evaluated through numerical simulation.It is the first engineering project that uses self-centering walls in a high-rise building.The seismic design procedure of such a high-rise building,using self-centering wall structures,is comprehensively reviewed in this work,and additional proposals are put forward.Description of construction detailing,including slotted beams,flexible wall-to-floor connections,embedded beams,and damper installation,is provided.The demonstration project promotes the concept of seismic resilient structures and contributes to the most appealing city planning strategy of resilient cities at present.The paper could be a reference for industry engineers to promote the self-centering wall systems worldwide.

Effects of green roof damping and configuration on structural seismic response

Sustainable structures are critical for addressing global climate change.Hence,their structural resilience or ability to recover from natural events must be considered comprehensively.Green roofs are a widely used sustainable feature that improve the environment while providing excellent occupant amenity.To expand their usage,their inherent damping and layout sensitivity to seismic performance are investigated in this study.The soil of a green roof can serve as a damper to dissipate the energy generated by earthquakes or other dynamic events.Results of preliminary analysis show that a green roof soil can increase localized damping by 2.5%under both dry and saturated conditions.Based on these findings,nonlinear time-history analyses are conducted on a three-story building in SAP2000 to monitor the structural behavior with and without a green roof.The increased damping in the green roof soil is beneficial to the structural performance,i.e.,it reduces the building displacement and acceleration by 10%and 12%,respectively.Additionally,certain configurations are more effective and beneficial to the structural response than others,which suggests the possibility of design optimization.Based on the findings of this study,new methods of modeling and considering green roofs in structural design are established.

Experimental study of the restoring force mechanism in the self-centering beam （SCB）

In the past, several self-centering （SC） seismic systems have been developed. However, examples of selfcentering systems used in practice are limited due to unusual field construction practices, high initial cost premiums and deformation incompatibility with the gravity framing. A self centering beam moment frame （SCB-MF） has been developed that mitigates several of these issues while adding to the advantages of a typical SC system. The self-centering beam （SCB） is a shop-fabricated, self-contained structural component that when implemented in a moment resisting frame can bring a building back to plumb after an earthquake. This paper describes the SCB concepts and experimental program on five SCB specimens at two-third scale relative to a prototype building. Experimental results are presented including the global force-deformation behavior. The SCBs are shown to undergo 5%-6% story drift without any observable damage to the SCB body and columns. Strength equations developed for the SCB predict the moment capacity well, with a mean difference of 6% between experimental and predicted capacities. The behavior of the restoring force mechanism is described. The limit states that cause a loss in system＇s restoring force which lead to a decrease in the selfcentering capacity of the SCB-MF, are presented.