Discussion on Construction Technology and Welding Deformation of High-Rise Steel Frame Structure

Because of urbanization,land resources in China’s cities has become increasingly scarce.Therefore,modern buildings are becoming taller,making high-rise steel frame structures the new favorite of the construction industry.However,the construction of high-rise steel frame structures requires advanced technology.If the construction technology is effectively implemented and the welding techniques of the construction personnel align with the requirements for high-rise steel frame structures,it can help mitigate deformations in the steel structure,thus preserving the overall construction quality of high-rise steel frame structures.To enhance the applicability of steel frame structures in high-rise buildings,this paper focuses on analyzing the optimization path for the construction process of high-rise steel frame structures.It introduces a tailored approach to control welding-induced deformations in steel frame structures,aiming to make a valuable contribution to the advancement of China’s construction industry.

Vibration Control of a High-Rise Building Structure:Theory and Experiment

In this study,an innovative solution is developed for vibration suppression of the high-rise building.The infinite dimensional system model has been presented for describing high-rise building structures which have a large inertial load with the help of the Hamilton’s principle.On the basis of this system model and with the use of the Lyapunov’s direct method,a boundary controller is proposed and the closed-loop system is uniformly bounded in the time domain.Finally,by using the Smart Structure laboratory platform which is produced by Quancer,we conduct a set of experiments and find that the designed method is resultful.

Experimental investigation of turbulent flows around high-rise structure foundations and implications on scour

Many studies have been undertaken to predict local scour around offshore high-rise structure foundations(HRSFs),which have been used in constructing the Donghai Wind Farm in China.However,there have been few works on the turbulent flow that drives the scour process.In this study,the characteristics of the turbulent flow fields around an HRSF were investigated using the particle image velocimetry technique.The mean flow,vorticity,and turbulence intensity were analyzed in detail.The relationship between the flow feature and scour development around an HRSF was elaborated.The results showed that the flow velocity increased to its maximum value near the third row of the pile group.The shear layer and wake vortices could not be fully developed downstream of the last row of the piles at small Reynolds numbers.The strong flow and turbulent fluctuation near the third piles explained the existence of a longtail scour pattern starting from the HRSF shoulders and a trapezoidal deposition region directly downstream of HRSF.This laboratory experiment gains insight into the mechanism of the turbulent flow around HRSFs and provides a rare dataset for numerical model verifications.

Flexible high-rise apartments with sparse wall-frame structure:A data-driven computational approach

Flexible housing resolves the fundamental conflicts between the long-standing structure and the evolving demands.We propose a computational method of optimizing the structural layout of high-rise residential buildings.Chinese high-rise apartment buildings have widely employed shear wall-frame structure in which one big room or multiple small rooms could occupy the same span.Fitting multiple floor plans into a fixed sparse scheme of shear walls and columns is feasible.We developed a computational framework to seek flexible structural schemes.A building scheme consists of a circulation core,shear walls,columns,and boundaries.The computer program automatically adapts floor plans to any drawn or generated scheme.Based on a large dataset of apartment layouts,the number of apartments that fit into a building scheme statistically reflects the flexibility of the scheme.If many hypothetical plans can fit into a wallframe structure in computer simulation,this structure could probably support several generations of unknown plans.Such a data-driven computational method provides the possibility of creating a one-to-many mapping between permanent structure and evolving apartment plans.

Structural form selection of the high-rise buildingwith the improved BP neural network

As civil engineering technology development,the structural form selection is more and more critical in design of high-rise buildings.However,structural form selection involves expertise knowledge and changes with the environment which makes the task arduous.An approach utilizing improved back propagation(BP)neural network optimized by the Levenberg-Marquardt(L-M)algorithm is proposed to extract the main controlling factors of structural form selection.Then,an intelligent expert system with artificial neural network is constructed to design high-rise buildings structure effectively.The experiment tests the model in 15 well-known architecture samples and get the prediction accuracy of 93.33%.The results show that the method is feasible and can help designers select the appropriate structural form.

Research and Implementations of Structural Monitoring for Bridges and Buildings in Japan

This paper provides a review on the development of structural monitoring in Japan, with an emphasis on the type, strategy, and utilization of monitoring systems. The review focuses on bridge and building structures using vibration-based techniques. Structural monitoring systems in Japan historically started with the objective of evaluating structural responses against extreme events. In the development of structural monitoring, monitoring systems and collected data were used to verify design assumptions, update speci cations, and facilitate the ef cacy of vibration control systems. Strategies and case studies on monitoring for the design veri cation of long-span bridges and tall buildings, the performance of seismic isolation systems in building and bridges, the veri cation of structural retro t, the veri cation of structural control systems (passive, semi-active, and active), structural assessment, and damage detec- tion are described. More recently, the application of monitoring systems has been extended to facilitate ef cient operation and effective maintenance through the rationalization of risk and asset management using monitoring data. This paper also summarizes the lessons learned and feedback obtained from case studies on the structural monitoring of bridges and buildings in Japan.

High-Rise Residential Reinforced Concrete Building Optimisation

In the last few decades structure optimisation has become a main task in a civil engineering project. As a matter of fact, due to the complexity and particularity of every structure, the great amount of variables and design criteria to considerate and many other factors, a general optimisation’s method is not simple to formulate. As a result, this paper focuses on how to provide a successful optimisation method for a particular building type, high-rise reinforced concrete buildings. The optimization method is based on decomposition of the main structure into substructures: floor system, vertical load resisting system, lateral load resisting system and foundation system;then each of the subsystems using the design criteria established at the building codes is improved. Due to the effect of the superstructure optimisation on the foundation system, vertical and lateral load resisting system is the last to be considered after the improvement of floor. Finally, as a case example, using the method explained in the paper, a 30-story-high high-rise residential building complex is analysed and optimised, achieving good results in terms of structural behaviour and diminishing the overall cost of the structure.

The Minaret of the Great Mosque in Algiers,a Structural Challenge

The Great Mosque in Algiers will be the third largest mosque in the world and its minaret the highest. The region has a high seismic risk. The project designed by a German team of architects and engineers is under construction and will be finished by 2016. Due to the minaret slenderness and to the special composite structure chosen to withstand lateral loading, the structural design faced some challenging aspects. The paper presents the design philosophy, some significant structural features and details of the minaret structure.

PROBABILITY MODEL AND SOLUTION ON EARTHQUAKE EFFECTS COMBINATION IN ALONG WIND RESISTANT DESIGN OF TALL-FLEXIBLE BUILDINGS

A model on the earthquake effects combination in wind resistant design of high-rise flexible structures is proposed in accordance with the probability method. Based on the Turkstra criteria, the stochastic characters of wind velocity, earthquake ground acceleration and excitations occurrence probability are taken into account and then the combination of the earthquake effects in structure wind resistant design is analyzed with the convolution approach. The results indicate that as for the tall flexible buildings whose lateral force is governed by wind loading, the maximum lateral loads verification with respect to the wind resistant design combined with earthquake effects may be more unfavorable compared with that in terms of the earthquake resistant design involving wind effects.

Seismic assessment of nature-inspired hexagrid lateral load-resisting system

This paper provides a general perspective of the seismic performance of a nature-inspired,honey-comb grid structural system,known as a hexagrid,under near-field ground motions.Seismic performance of this skeleton is then compared to that of a bundled-tube,as a conventional and efficient load-resisting system in order to provide a better perception of the seismic behavior of a hexagrid skeleton.Two 20-story buildings with bundled-tube and hexagrid skeleton were studied.Nonlinear behavior of the structures was investigated through 3-D finite element computer models and nonlinear time history analyses by subjecting the models to seven three-component records of scaled near-field ground motions.Distribution of peak inter story drift and corner beam-column joint rotations were calculated and compared.Results indicated that by replacing the exterior columns of the bundled-tube system with inclined beam-column elements of nature-inspired hexagons,lateral stiffness of the building increased and it would tolerate less deformations before global dynamic instability is reached.The presence of inclined columns in the hexagrid skeleton helped to concentrate local nonlinearities in ring beams rather than exterior columns.

Decentralized damage diagnostic technique for tall buildings using VARMAX model

Civil infrastructure,especially buildings,are becoming more slender,tall,and multipurpose,creating a need to continuously monitor their health to ensure the safety and security of human lives and assets.While the majority of structural health monitoring techniques use measurements from the entire structure,in this study,an output-only damage diagnostic technique using a decentralized concept(subdomain-based)for tall buildings and employing a vector form of the autoregressive moving average with exogenous input(VARMAX)model is proposed,which offers reduced instrumentation and data handling requirements.Unlike other decentralized approaches,this technique predicts more than one DOF at a time so the number of subdomains required for the diagnosis of the complete structure is minimized.The proposed subdomain-based damage diagnostic algorithm works with ambient loads and does not require any correlated numerical models since it is solely based on measured data.The proposed algorithm can identify the time instant of damage,spatial location(s)and characterize the damage intensity.Efforts have been made to account for confounding factors such as environmental and operational variabilities separate from measurement noise to avoid false positive alarms.The effectiveness of the proposed technique is illustrated using synthetic time history responses from a twenty-story framed structure under ambient loading and an experimental study on a ten-story framed structure.Both numerical and experimental investigations confirm the effectiveness of the method and its robustness to environmental/operational variabilities and measurement noise.

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.

Wind-induced vibration control of Hefei TV tower with fluid viscous damper

The Hefei TV tower is taken as an analytical case to examine the control method with a fluid viscous damper under wind load fluctuation.Firstly,according to the random vibration theory,the effect of fluctuating wind on the tower can be modeled as a 19-dimensional correlated random process,and the wind-induced vibration analysis of the tower subjected to dynamic wind load was further obtained.On the basis of the others'works,a bi-model dynamic model is proposed.Finally,a dynamic model is proposed to study the wind-induced vibration control analysis using viscous fluid dampers,and the optimal damping coefficient is obtained regarding the wind-induced response of the upper turret as optimization objectives.Analysis results show that the maximum peak response of the tower under dynamic wind load is far beyond the allowable range of the code.The wind-induced responses and the wind vibration input energy of the tower are decreased greatly by using a fluid viscous damper,and the peak acceleration responses of the upper turret is reduced by 43.4%.

Modeling the collapse of the Plasco Building.Part I:Reconstruction of fire

In recent years,fires in tall buildings have become more frequent,which costs billions of dollars each year and the loss of many human lives.The facade fire in the Grenfell tower made the structure uninhabitable,and the collapse of the three World Trade Center(WTC)towers is the total structural failure caused by fire.Despite such events,no well-defined methodology exists to reconstruct both fire and structural behaviors and carrys out the forensic investigation of a building fire.This Part I paper collects the evidence of the Plasco Building fire and generates a coherent timeline to reconstruct the fire processes.The vertical and horizontal fire spread of the building is reconstructed using computational fluid dynamics(CFD)fire modeling and calibrated against the evidence library.The spatio-temporal temperature history from the fire modeling provides realistic fire scenarios to simulate the structural response.The fire simulation results are used as boundary conditions to be transferred to a finite element analysis tool for a detailed structural analysis to determine the likely collapse mechanism of the Plasco Building in Part II.The methodology presented in this paper to reconstruct the fire can also guide the structural fire safety engineers to improve the building fire-safety and life-safety strategies.