Adjacent Buildings Research Articles

Assessment of Safety of Masonry Buildings near Deep Excavations: Ultimate Limit States

It is a common practice to construct new buildings in the close vicinity of existing buildings. New buildings require deep excavations, which cause non-uniform displacement of the ground, causing a negative impact on the safety and technical conditions of adjacent buildings, including masonry buildings. The fundamental condition to verify structural safety is the knowledge of impacts and the load-bearing capacity of non-strengthened or strengthened structures. Safety is provided via strengthening the structure against deformations related to the ground displacement or by reducing non-uniform displacements of the building structure. This paper focuses on strengthening the ground and underground parts of masonry buildings. It also describes general requirements for providing safety of buildings according to the standard Eurokode 0 and the simplified method for protecting building structures with the use of steel tie rods. Based on the design methods for masonry structures specified in Eurocode 6 and the know-how of the authors in the field of protecting buildings in mining areas, the original method was proposed to determine the required area of reinforcement in the form of steel rods. Also, the original methods were introduced to verify ULS for inclined walls primarily under vertical load and shearing of pillars between openings. In addition to these analytical methods, this paper also illustrates methods for strengthening the ground and underground parts of masonry buildings. Presented in this paper, original solutions used to determine the strengthening of masonry structures and original models used to verify ULS for deflected walls primarily under vertical load can be directly employed in the design practice. The standard criteria were applied and the effects of building deflections, which are not specified in Eurocode 6, were considered.

Research on Optimization Design of Tunnel Blasting Scheme Adjacent to Buildings

The section of Jialingjiang Road Station to Xiangjiang Road Station along Qingdao Metro Line 13 is located in Qingdao, China. All of them show obvious characteristics, being soft on the top and hard on the bottom, and the interval tunnel is faced with the problem of existing adjacent buildings. In order to ensure the smooth progress of construction, as well as minimize the damage to the buildings, a new mechanical excavation combined with a blasting construction scheme for the adjacent buildings is proposed. In this scheme, the step method is used for excavation. The upper step is in the weak stratum, and the mechanical method is therefore used for excavation; the lower step is in the hard stratum, and the drilling-and-blasting method is thus used for excavation. Using FLAC3D 5.0 finite difference software and the method based on blasting an equivalent load, the vibration velocity at adjacent buildings caused by the combined mechanical excavation and blasting scheme, as well as the traditional full-section blasting scheme, is compared and analyzed. Further, the construction parameters of the combined mechanical excavation and blasting scheme are compared and selected based on building settlement, the plastic zone of surrounding rocks, building vibration velocity and other factors. The results show that under the mechanical excavation blasting scheme, the peak particle velocity of each monitoring point decreases significantly compared with that under the full-section blasting scheme, with a maximum reduction of 61.1%, which is within the allowable range of the project, demonstrating the rationality of the new scheme. Finally, the mechanical excavation advance in the upper step is determined as 0.5 m. The optimized parameter construction effect is monitored and evaluated, the problems encountered in the project are successfully solved using the combined mechanical excavation and blasting scheme, and the expected construction period is shortened by 3 months, which shows the rationality of the blasting construction scheme proposed and its parameters, as well as the validity of the calculation results. The research results can be used as a reference for the construction scheme design of similar projects.

Seismic behaviour of reinforced-masonry aggregate under different types of interaction between adjacent dwellings

Assessing the seismic vulnerability of existing buildings is an essential task for the management of earthquake disasters. For this purpose, the seismic behaviour of buildings is usually determined under the assumption of isolated conditions, although aggregate structures are one of the most common typologies found in urban centres. This study aims to investigate the nonlinear static behaviour of aggregate dwellings consisting of grouted reinforced concrete block configurations commonly observed in San José, Costa Rica. This research investigates the use of several strategies to model connections between adjacent buildings which are typically found in modern building practises in this country. The methodology used here to analyse the seismic behaviour of isolated and row-aggregated dwellings reveals significant differences in their response under seismic loads, especially when acting perpendicular to the aggregate. The study reveals that the type of interaction considered between adjacent buildings has a very important impact on the seismic capacity and failure mechanisms of the aggregated structures. This procedure can also be applied to the vulnerability assessment and retrofit of existing aggregates.

Effects of shear wave velocity and soil structure interaction on the structural pounding during earthquakes

It has been found that in the event of a strong earthquake, and due to insufficient distance between two adjacent structures, the lateral movement at the top of structures may cause collisions between them. This phenomenon, commonly known as seismic collision, can generate impact forces that were not considered during the initial design of the structure. These forces can cause significant structural damage or lead to complete collapse of the structure. The main purpose of this paper is to study the coupled effects of soil flexibility and impact between adjacent buildings undergoing seismic excitation. To capture the impact forces between the structures during the collision, a modified linear viscoelastic model was used effectively. Particular attention has been paid to studying the effects of shear wave velocity, first on the soil structure interaction and then on the collision response of adjacent structures. Three configurations of adjacent structures were analyzed: light-light, light-heavy, and heavy-heavy structures. The results obtained through this analysis showed that the dynamic response and the impact force of the structures depend essentially on the interaction between the structure, the foundation, and the soil.

The Influence of Construction Methods on the Stability of Tunnels and Ground Structures in the Construction of Urban Intersection Tunnels

The construction of intersection tunnels in urban induces multiple stress redistribution in the surrounding rock, leading to engineering disasters such as instability in rock strata during excavation, disturbance of supporting structures in existing tunnels, and subsidence of ground adjacent buildings. Employing an appropriate construction method is crucial in circumventing excessive stress concentrations and large-scale rock strata subsidence, making it a key aspect of urban intersection tunnel engineering. In this paper, a numerical model for an urban intersection tunnel is developed based on an underground circular road project in a central business district. We conduct numerical simulations of the excavation processes using the full-section method, step method, and center cross diagram (CRD) method, respectively. The findings indicate that while different construction methods do not change the variation trends of surrounding rock stress and displacement, adjacent ground building deformation, and existing tunnel convergence, they affect the variation degrees. The maximum compressive and tensile stresses in the surrounding rock caused by the CRD method are the smallest, which are 3.56 MPa and 0.76 MPa, respectively. The maximum arch subsidence affected the amount, and horizontal convergence affected the amount of branch tunnel #1 caused by the CRD method are the smallest too, which respectively are 1.428 mm and 0.931 mm. The foundation subsidence and overall inclination of the ground building resulting from the three methods are identical. Then, we discuss the construction safety of the three methods and obtain the influence order on construction stability, which is as follows: full-section method > step method > CRD method. It is concluded that the CRD method is the most suitable for urban intersection tunnel engineering in terms of safety. This study could offer valuable insights for selecting construction methods in urban intersection tunnel engineering and provide a foundation for evaluating the safety and stability of tunnel construction.

Numerical and Experimental Investigations of Interference Effect of Adjacent Buildings on Sand and Fill Deposits

Numerical and Experimental Investigations of Interference Effect of Adjacent Buildings on Sand and Fill Deposits

Relative Variability in Streetscape Skeletons and Spatial Association: Application for Identifying Harmonious and Inharmonious Streetscape Skeletons in Tokyo

Whether or not a streetscape skeleton (defined as the 3D street space) is harmonious depends on the degree of difference between heights and setbacks of adjacent buildings, which is called the relative variability in the streetscape skeleton, but this has generally been overlooked. Because streetscape skeletons are ambiguous, evaluating whether or not they are harmonious is thus conceptually and technically challenging. This article, therefore, considers the relative variability in streetscape skeletons and their spatial associations and answers the following question: where are harmonious or inharmonious streetscape skeletons locally clustered? The relative variability in the streetscape skeletons in the districts of the Tokyo metropolitan region was computed, where building heights and setbacks are directly controlled through streetscape promotion district planning stipulated in the City Planning Act. The spatial association of the relative variability in streetscape skeletons was then visualized to identify where streetscape skeletons are harmonious and inharmonious. The results showed that although harmonious streetscape skeletons are spatially clustered inside the domain bounded by wider streets, such clusters are small and spatially scattered. We, therefore, concluded that the effectiveness of direct controls through streetscape‐promoting district planning to maintain and create harmonious streetscape skeletons is spatially limited and thus insufficient.

IoT-assisted energy cooperation in adjacent buildings with interrupted utility

Facing severe power outages primarily due to generation shortfalls and transmission line losses, Pakistan is seeing an overwhelming shift in renewable energy sources both in residential and industrial buildings. Motivated by the same, efficient load sensing and management techniques – already available in the literature – are being adopted in modern construction their efficiency in terms of cost-savings, however, is still questionable. In this work, an Internet-of-Things (IoT) assisted energy cooperation scheme for adjacent buildings equipped with renewable energy sources is proposed for enhanced efficiency in energy management, with additional generators to cater for the power outages. The IoT network consists of a combination of local and global aggregators; while each building is equipped with a local aggregator to determine the current state of electricity, heating and cooling consumption and generation, the global aggregator, on the other hand, acts as an intelligent hub for energy cooperation. The latter determines the amount of energy to be shared among the buildings to minimize the overall energy cost. For theoretical realization of the proposed scheme, a comprehensive energy cooperative mathematical model is developed, whose objective function is presented as a nonlinear optimization problem – linearized using McCormick’s Envelopes. Our simulation results reveal that the proposed framework promises increased efficiency in terms of energy cost-savings; we support our claims with a detailed quantitative analysis.

Sustainable Urban Energy Solutions: Investigating the Solar Potential of Vertical Façades Amidst Adjacent Buildings in Kuala Lumpur, Malaysia

This article explores the impact of adjacent buildings on solar exposure for photovoltaic (PV) applications in high-rise urban areas in Malaysia. The rapid urbanization and population density in Malaysia's high-rise areas have increased energy demand, necessitating the exploration of alternative energy sources. Integrating PV systems into vertical façades offers a promising solution for maximizing energy generation in space-constrained urban environments. However, the efficacy of PV systems is influenced by adjacent buildings, including their arrangement, height, and orientation, which affect solar exposure and energy generation potential. Understanding these effects is crucial for optimizing PV system design and placement. This study aims to investigate the relationship between adjacent buildings and solar exposure for PV panels mounted on high-rise buildings in Malaysia. By examining these effects, the research provides valuable insights for urban planners, architects, and renewable energy practitioners involved in sustainable urban development. The findings will inform decisions regarding the integration of PV systems, promoting renewable energy adoption, and reducing the environmental impact of urban areas. The article also discusses Malaysia's climate, energy consumption, and solar radiation potential, emphasizing the need to harness solar energy in a country blessed with abundant sunlight. The challenges faced by current air conditioning systems and building-integrated photovoltaic (BIPV) applications in Malaysia are outlined, along with efforts to address them through energy-efficient systems and awareness campaigns. The research conducted simulations using a 3D model in Kuala Lumpur, Malaysia, considering different heights and distances of adjacent buildings. The software used for simulations was IES-VE, which offers various modules for energy consumption analysis. The results demonstrate how adjacent buildings affect the annual average energy for different scenarios, highlighting the importance of distance and height. The findings provide insights into the monthly average energy variations and emphasize the relationship between adjacent building height and average energy levels. Overall, this research contributes to the efficient utilization of vertical façades for harnessing solar energy in high-rise urban areas, supporting Malaysia's sustainable energy goals while ensuring urban environment liveability and resilience.

Face-directed assembly of tailored isoreticular MOFs using centring structure-directing agents

Building blocks with low connectivity and no embedded directionality are prone to polymorphism, as demonstrated by the diversity of 4-connected zeolitic nets (>250). As a result, their deployment for design in reticular and isoreticular chemistries remains a challenge. However, the ability to control geometrical peculiarities offers potential to deviate from the assembly of default structures. Here we report the face-directed assembly of >20 isoreticular zeolite-like metal–organic frameworks (ZMOFs) by using polytopic expanding and tightening centring structure-directing agents (cSDAs). The cSDAs are selected with the appropriate geometrical coding information to alter and control the orientation of adjacent supermolecular building blocks. The ZMOFs have an underlying sodalite (sod) topology that is remarkably suited for the rational assembly of multinary materials. In addition to a variety of metal cations (In, Fe, Co and Ni), a diverse range of cSDAs (di-, tri-, tetra-, hexa-, pyridyl or imidazole) are used and combined. Our approach enables isoreticular possibilities at both extremities of the porous materials spectrum: In-sod-ZMOF-102 exhibits small pore aperture suitable for efficient separation, while Fe-sod-ZMOF-320 with 48-Å-wide mesopores exhibits high hydrogen uptake, methane storage working capacity and a high gravimetric working capacity for oxygen.

A Mathematical Approach for Predicting Sufficient Separation Gap between Adjacent Buildings to Avoid Earthquake-Induced Pounding

Studies on earthquake-related damage underscore that buildings are vulnerable to significant harm or even collapse during moderate to strong ground motions. Of particular concern is seismic-induced pounding, observed in numerous past and recent earthquakes, often resulting from inadequate separation gaps between neighboring structures. This study conducted an experimental and numerical investigation to develop a mathematical equation to calculate a sufficient separation gap in order to avoid the collision between adjacent mid-rise steel-frame buildings during seismic excitation. In this study, the coupled configuration of 15-storey & 10-storey, 15-storey & 5-storey, and 10-storey & 5-storey steel frame structures was considered in the investigation. The investigation concluded with a large number of data outputs. The outputs were used to predict structural behavior during earthquakes. The obtained data were categorized into three main categories according to the earthquake's Peak Ground Acceleration (PGA) levels. Also, the derived equations were divided into three different equations to estimate the required seismic gap between neighboring buildings accordingly. The derived equations are distilled to empower engineers to rigorously evaluate non-irregular mid-rise steel frame buildings. Doi: 10.28991/CEJ-2023-09-10-02 Full Text: PDF

Three-dimensional Finite-element Analysis of the Influence of Tunneling on Pile Foundations

Advancing tunnel boring machine (TBM) during tunnel construction induces a surface settlement, affecting adjacent buildings and facilities. A three-dimensional finite-element model (Plaxis 3D) was used to simulate and analyze this process. A comparison between the numerical model and field measurements of the Greater Cairo Metro (Line 3) was made to validate the obtained results. A sensitivity analysis was conducted to determine how changes in some parameters, such as constitutive models, pile position relative to the tunnel axis and pile spacing, affect the results of the finite-element model. Three constitutive models: hardening soil small (HSS), hardening soil (HS) and the Mohr-Coulomb (MC) models, were used to evaluate the effect of the constitutive models on the results. From the numerical analysis, it is clear that the numerical results are in good agreement with field measurements. The results of the HSS model are more realistic and closer to field measurements than those of the HS and MC models. Furthermore, the effect of the tunnel construction on the settlement of adjacent piles is virtually null at a distance of 2 D (where D is the tunnel diameter). Finally, increasing the pile spacing decreases the effect of tunnel excavation on adjacent pile foundations. KEYWORDS: Tunneling, Numerical models, Constitutive models, Pile foundation, Pile spacing

Modeling the dynamic safety management of buildings adjacent to karst shield construction: An improved cloud Bayesian network

Shield construction in karst tunnels inevitably causes settlement deformation and even damage to surrounding buildings. To accurately evaluate the security of neighboring buildings, a hybrid method combining an improved cloud model (CM) and a Bayesian network (BN) is proposed for dynamic security analysis and the evaluation of neighboring buildings. First, through engineering practice, simulation analysis and literature research, the safety risk factors and evaluation criteria for adjacent buildings influenced by shield construction in karst areas are determined, and a BN for safety evaluations of adjacent buildings is constructed. The improved CM is used to model the uncertainty of the risk state, realize the discretization of continuous data and obtain prior knowledge. By improving the cloud Bayesian network (CBN) to perform three kinds of comprehensive analyses, including forward prediction reasoning in advance, sensitivity analysis and reverse risk diagnosis for events, and appropriate risk management and control measures, the dynamic safety perception and control of buildings adjacent to karst shield construction is realized. The data for buildings under construction adjacent to Guiyang Rail Transit Line 3 are used to demonstrate the applicability and effectiveness of the proposed method. The contributions of the research results are as follows: (a) The key risk factors affecting the safety of buildings adjacent to shield construction areas in karst zones are extracted, and an evaluation index system and an evaluation standard are established; (b) An improved CM is used to describe the fuzziness and uncertainty in the process of node state discretization in a risk inference network, thus improving the prediction and diagnosis performance of BN security evaluation models; (c) The improved cloud Bayesian model is applied to construct a knowledge representation-based safety model of buildings adjacent to karst shield construction areas, and accurate perception and control diagnosis results are obtained for effective safety risk prediction and control, providing a reference for other similar projects.

Application of geodetic methods for preventing emergencies in the construction and operation of buildings and structures

Introduction. The paper describes distortions of geometry in buildings and structures under construction as well as those already commissioned, which increase the risk of an emergency. The paper also shows the reasons for controlling the geometry for its compliance with design form and stability, as well as possible impact of deviations in the design geometry on adjacent buildings and structures.Aim: to analyze and describe the application of geodetic methods for preventing emergencies in the construction and operation of buildings and structures.Materials and methods. The paper presents methods and techniques for measuring the deformations of buildings using modern robotic tacheometers, inclinometers, satellite equipment, as well as hydrostatic leveling, in order to obtain reliable and valid parameters of the deformed state of building structures under both static and dynamic effects on the building or structure.Results. The paper explains the operating principles of measuring systems using automatic geodetic monitoring systems. The authors describe the process of determining displacements and deflections during the erection of large-span shells of unique buildings. These include the steel framed dome of the Luzhniki Stadium in Moscow, Russia, which has the largest unsupported span for structures of this class (310 m), large-span transformed shell of the Gazprom Arena Stadium in Saint Petersburg, and large-span shell of the Kazan Arena Stadium in Kazan, Russia. Deflections and displacements of the reference points of the steel pyramid were determined for the Opening Ceremony at the Kazan Arena Stadium. The paper also presents the methods for determining the parameters of deformations during the construction of the Rhythmic Gymnastics Center in Luzhniki, metro lines in Moscow, and Kashirskaya–Karacharovo section of the Moscow ring railroad. Measurement methods have been developed and implemented for all these facilities.Conclusion. The above measurement methods are successfully used to determine horizontal displacements and deflections for monitoring the deformations of buildings and structures, which increases their reliability and safety during construction and operation.

Lessons learnt from a full-scale installation of energy walls

The possibility of equipping diaphragm walls as ground heat exchangers to meet the full or partial heating and cooling demand of overlying or adjacent buildings has been explored in recent years [1, 2, 3, 4]. In this extended abstract a specific installation of energy diaphragm walls is described and the lessons learnt during the implementation discussed.
 The construction site is located in the city of Torino, in the campus of the Politecnico di Torino, where a new underground car park is under construction. The structure consists of four underground floors to be used as a car park for the staff at the academic site. The area of the excavation corresponds to a rectangle 173 m long and 35 m wide. The excavation is supported by more than 170 diaphragm walls. The maximum depth reached by the bulkheads is 17,65 m, while the excavation reaches approximately 15 m below the current ground level and above the water table. The ground at the site is an alluvial deposit consisting of sand and gravel locally cemented to form layers of conglomerate [5]. The construction process involves excavation by means of clamshell buckets, filling by bentonite slurry, lowering of the steel cage in two sections and bottom up filling by concrete.
 To boost the sustainability of its campuses, the Politecnico decided to make effective use of energy geostructures and to equip all single diaphragm walls with heat exchangers. A series of PE-Xa (cross-linked polyethylene) pipes of reduced diameter (32 mm) was introduced to allow the circulation of a heat transfer fluid.
 Considering that the steel cage of the diaphragm walls is constituted of two elements, the pipes were binded to the lower section of the rebar cages while laying in the construction site, before being lowered into the excavation. Two U-shaped pipes are installed for each diaphragm wall so that a distance of 60 cm separates each pipe. The inner pipes will be connected to the inlet, while the external pipes will be connected to the outlet. Pipes were placed on site with spacers to ensure the adequate passage of the concrete aggregates and avoid problems due to contacts with the ground at the excavation contour (Figure 1(a)). A distance of about 10 cm is achieved thanks to the spacers. An extra length of pipes is fixed to the rebar cage for later use.
 The steel cage is lifted by the crane and then lowered into the excavation. Once in place, it is hung to be connected with the upper part of the cage. Then lowering starts again. In this case, the extra pipe, previously hung onto the lower steel cage are unrolled and connected to the upper part of the steel cage by hand by the workers. This process requires the lowering of the cage to be interrupted systematically to allow for the workers to quickly make fast connections (Figure 1(b)). Once the whole steel cage is within the ground, the pipes are placed at rest with a protective coating. All pipes will be connected to inlet and outlet header pipes running outside the car park excavating area and directed to the central thermal power plant of the campus.
 The pipes’ condition was tested several times during the installation. First, a visual check, a pressurization and an emptying were performed before connecting the pipes to the lower part of the steel cage. Then, the pipes were filled with water before concrete casting and kept under pressure at 4 bar for 12 hours minimun during curing. The installation was considered successful if the pressure didn’t reduce by more than 0.1 bar. Despite the design considered the risk of losing up to 10% of the pipes due to unpredictable failures (e.g. crush, failures, contact, etc.), the final result, due to the careful workmanship, was that none of them had to be abandoned.
 The excavation of the area started in 2022, while completion and commissioning of the underground car park are expected for 2024. Connection of the heat exchangers to the heating system will take place after completion resulting in the largest application of energy walls in Italy.

Analysis of Surface Settlement Induced by Shield Tunnelling: Grey Relational Analysis and Numerical Simulation Study on Critical Construction Parameters

Excessive surface settlement poses significant challenges to shield tunnelling construction, resulting in damage to adjacent buildings, infrastructure, and underground pipelines. This study focused on investigating the surface settlement induced by shield tunnelling during the construction of Qingdao Metro Line 6 between Haigang Road Station and Chaoyang Road Station. Firstly, the settlement data from the left line of the shield tunnel were evaluated by grey relational analysis. The relational coefficients were calculated to assess the correlation degrees of each influential parameter. Subsequently, the four critical influential parameters with the highest relational degrees were chosen to investigate their effects on surface settlement through numerical simulations under different scenarios. The results show that the four parameters with the highest relational degrees were thrust, grouting pressure, earth pressure, and strata elastic modulus. It should be noted that the strata elastic modulus significantly affects surface settlement, while the grouting pressure influences the settlement trough width in weak strata. Moreover, improper thrust magnitude can lead to an increase in surface settlement. Based on these findings, recommendations are proposed for the right-line tunnel construction and practical countermeasures for surface settlement during shield tunnelling construction are provided.

Settlement Analysis of Ground Surface and Adjacent Building Caused by Driving and Expansion Excavation of Shield Tunnel Using Artificial Freezing Method

The artificial freezing method can effectively improve the stability of strata and provide favorable conditions for the construction safety of shield tunnel in water-rich strata. Based on the frozen shield tunneling project of a metro station, which is close to important buildings, a reasonable freezing method and parameters are proposed in this paper. The simulation model was established by using Plaxis 3D finite element software (Version 2017). The numerical model was verified based on a large amount of field data. The characteristics of segment deformation, ground surface settlement and vertical displacement of buildings were compared between frozen layer and nonfrozen layer during shield tunnel excavation. It was found that segment deformation in the nonfrozen layer is three times that in the frozen layer. The surface settlement above the frozen layer is less than 2 mm. Expansion excavation of shield tunnel was carried out to meet the space function of subway station using artificial freezing method. The deformation of frozen layer was compared between full section excavation and partial excavation. It was found that the deformation of the former is 4.5 times that of the latter, so the partial excavation was chosen as the main research object. Subsequently, the characteristics of vertical displacement and surface settlement of buildings under partial excavation were studied. It was found that the vertical settlement of buildings away from the frozen layer is greater than that of buildings near the frozen layer. All settlement values meet the requirements, thus ensuring the feasibility of partial excavation and ensuring the safety of construction.

Design and analysis of nonlinear numerical algorithm for seismic response of structures based on HVSR algorithm.

Earthquake is one of the main factors causing structural disasters in current buildings. Under earthquake action, adjacent building structures are generally in different vibration stages, and collisions may occur in the structures, which may cause serious damage to the structure. In order to prevent certain earthquakes from damaging the designed buildings, this article mainly introduced the design and analysis of a numerical algorithm for seismic nonlinear structural dynamic response based on the HVSR algorithm. This article evenly divided the acceleration response time series into 15 time periods and then selected the position corresponding to the peak point of instantaneous amplitude within each period as the selected data point position. The same seismic load can be applied at the bottom of the established nonlinear model to extract the dynamic response data of the top layer of the structure, and then, the instantaneous amplitude and corresponding instantaneous phases and frequencies of the main components of the structural dynamic response can be extracted through the time-varying filter and Hilbert transform based on the discrete analytic mode decomposition. Under the influence of these four ground motions, the collision force within the range of 0-50 kN accounted for over 87% of the total number of collisions. In the comparison results of collision response to peak displacement, the four ground motions all led to structural collision, and the collision inhibited the positive peak displacement response of node 1512. Compared with noncollision, the peak displacement was reduced by 27.273, 33.675, 27.727, and 37.248%, respectively. The peak displacement of 1512 nodes was suppressed and reduced by 18.856%. The results indicate that the HVSR algorithm can obtain the instantaneous characteristic parameters of nonlinear structural dynamic response and achieve model correction.

Quantitative correlation between buildings air permeability indicators: Statistical analyses of over 400,000 measurements

Several building airtightness databases were created in many European countries thanks to the development of commissioning tests. However, comparing building performance across countries can be challenging, as various indicators are used to measure the air permeability of buildings depending on the specific application and the nation’s regulation. This paper examines the comparison of air permeability indicators used in various countries and seeks to establish default conversion equations between these indicators. To do so, a statistical analysis was conducted on the French database. The most frequently used indicators are the specific air leakage rate per envelope area and the air change rate at a reference pressure of 50 Pa in most countries and 4 or 10 Pa in a few other countries. The compactness appears to be a relevant geometric parameter for characterising the relationship between the air permeability indicators, as it encapsulates both the shape of the building and its contact with adjacent buildings. Correlations between the different indicators have been calculated according to the building type and compactness. Thus, this study concludes that indicators can be reliably estimated by knowing the building type and geometry. A general correlation is provided with a higher estimation error if the geometry data is missing.

Seismic resilient design and negative stiffness-assisted nonlinear isolation system for adjacent non-coaxial buildings linked by corridors

Adjacent non-coaxial buildings have been widely built owing to complementary functions, while the non-coaxial layout could cause a great torsion effect and seismic-induced damage. This study proposes a negative stiffness-assisted hybrid isolation system and a corresponding earthquake-resilient design methodology to upgrade the multi-performances of the adjacent non-coaxial buildings and linking corridors. The hybrid isolation system includes synthetic employment of various isolators and negative-stiffness amplification systems comprised of nonlinear viscous dampers for adjacent structures, as well as tailored friction bearing for linking corridors. The mechanical property and model of the adjacent non-coaxial buildings are established, based on which a typical case is introduced. Next, the conception of the earthquake-resilient design method and procedure is elaborated, following which the functionality of each component in the hybrid system is investigated. The advantages of the developed hybrid isolation system and design methodology are illustrated by a systematic parametric analysis and time history analysis for the typical case. The results show that the torsional effect can be a dominant problem in non-coaxial adjacent buildings, which can be solved by the flexibly tailored negative stiffness effect produced by the negative stiffness-assisted isolation system. The collaboration within the proposed hybrid isolation system can produce improved isolating and enhanced nonlinear energy dissipation effects on adjacent buildings, simultaneously limiting the isolation displacement without weakening the isolating effect. The optimized friction sliding bearings effectively reduce the relative torsion concentrated on the linking corridors with a maintained function. The hybrid isolation system and earthquake-resilient design can be adopted as a high-efficiency solution to the non-coaxial linked historic buildings with insufficient seismic resistance.