Regular Building Research Articles

A Review-strengthening of reinforced concrete beams with textile-reinforced concrete

Numerous problems that can occur during regular building use may necessitate the need for reinforced concrete RC members to be strengthened. An increase in live loads or structural damage is two examples. Various techniques can be used to increase load-carrying capability. Concrete reinforcement with textile-reinforced materials (TRC) is a more recent option. For almost all active forces, this strengthening procedure is appropriate. For bending, shear, torsion, or axial forces, strengthening is an option. Due to their many appealing qualities, characteristics as their high specific strength (i.e., strength to weight ratio), resistance to corrosion, the convenience of use, speedy installation, and little variation in cross-section, (TRC) have become more and more popular among structural engineers for strengthening and retrofitting projects The conclusions made from the experimental results of members made of reinforced concrete strengthened in shear suggest that textile-mortar composites greatly increase shear resistance, with the gain increasing with the number of layers. This review focuses on strengthening RC beams in flexure by textile-reinforced concrete. According to the authors, TRC jacketing is a very promising technique for increasing reinforced concrete components’ confinement, in addition to their shear and bending capability, which is necessary for seismic retrofitting and strengthening.

On the value of the von Kármán constant in the atmospheric surface layers over urban surfaces

Large-eddy simulations of turbulent boundary flow over different urban-like surfaces in neutrally stratified conditions are performed to study the atmospheric surface layer characteristics over urban areas. A simple method based on the vertical profile of the dimensionless velocity gradient is used to identify the inertial sublayer (ISL) in all cases. The results show that the mean wind profiles in the different urban ISLs can all be generally described by the logarithmic wind profile. However, for the idealized urban surfaces composed of regular building block arrays and the realistic urban surface case, the von Kármán constant (κ) in the ISL is found to be significantly smaller (in the range of 0.21–0.27) than the typically adopted value of 0.4. As κ is a key constant in the parametrizations of urban surface flows and is usually assumed to be ≈0.4 in existing surface parametrization models, a significantly smaller κ implies that large uncertainties may exist in the predictions of the momentum, heat, and scalar turbulent fluxes over urban surfaces using these models.

Fast Models for Predicting Pollutant Dispersion inside Urban Canopies

A fast pollutant dispersion model for urban canopies is developed by coupling mean wind profiles to a parameterisation of turbulent diffusion and solving the time-dependent advection–diffusion equation. The performance of a simplified, coarse-grained representation of the velocity field is investigated. Spatially averaged mean wind profiles within local averaging regions or repeating units are predicted by solving the three-dimensional Poisson equation for a set of discrete vortex sheets. For each averaging region, the turbulent diffusion is parameterised in terms of the mean wind profile using empirical constants derived from large-eddy simulation (LES). Nearly identical results are obtained whether the turbulent fluctuations are specified explicitly or an effective diffusivity is used in their place: either version of the fast dispersion model shows much better agreement with LES than does the Gaussian plume model (e.g., the normalized mean square error inside the canopy is several times smaller). Passive scalar statistics for a regular cubic building array show improved agreement with LES when wind profiles vary in the horizontal. The current implementation is around 50 times faster than LES. With its combination of computational efficiency and moderate accuracy, the fast model may be suitable for time-critical applications such as emergency dispersion modelling.

Automatic identification of building structure types using unmanned aerial vehicle oblique images and deep learning considering facade prior knowledge

ABSTRACT Building structural type information is the foundation for seismic risk assessment and management since it reflects the behavior of buildings under seismic load. However, in earthquake-prone regions, most of this information is out-of-date or nonexistent. This paper proposes a deep learning-based method for automatically identifying building structural types from unmanned aerial vehicle (UAV) oblique images. The method consists of four steps: (1) collect facades of buildings with different structural types by web crawler technology as a sample set; (2) construct a convolutional neural network with a facade prior knowledge attention branch and train the model using the sample set; (3) extract building facades from UAV oblique images based on the georeferencing results of feature points as the test set; (4) identify building structural types by inputting the test set into the trained model. Three cases have been selected to verify the feasibility and applicability of the method. The average recall rate of 85% and the average F1 score of 83% have been achieved in areas with regular building distribution. This method integrates multidisciplinary knowledge to provide a solution for rapid collection of building vulnerability information, and expands the role of oblique photography data in urban management and disaster prevention planning.

Economic Earthquake Resistance Construction of High-Rise Buildings

The economic perception of earthquake resistance construction for medium- to high-rise RCC buildings is examined in this paper. The conventional way of creating high-rise buildings is not financially viable without a shear wall to withstand seismic energy. Framed structures with irregular floor plans that vary in size, shape, and geometry are also expensive. Many studies have been conducted recently on the Coupling Ratio (CR). The current analysis investigates the behavior of the coupled shear wall and the CR for an affordable earthquake resistance construction including the shear wall within a range of 30 % to 45 %. The study shows that shear walls could be reduced at 40–50 % and at 60–70 % of the base height for regular and irregular buildings, respectively. The current study also comes to the conclusion that coupled shear wall earthquake-resistant construction is more practical than the conventional approach because couple beams can be repaired with ease.

EVALUATING STRUCTURAL RESILIENCY OF PUBLIC SCHOOLS AS EMERGENCY SHELTERS IN NATURAL DISASTERS

Public schools are the second largest sector of public infrastructure spending following highways, and there are about 84,000 public schools with 100,000 buildings in the United States. In addition to their primary functions as learning facilities, public schools usually serve an important role as emergency shelters and community resilience hubs during and after natural disasters, such as earthquake, windstorm, and flooding. In order to effectively fulfill the secondary function as emergency shelters, the school infrastructures need to be operational during and after the disasters. However, there are gaps between the existing school building structural capacities and the requirements of essential buildings as emergency shelters. In this paper, a generic 3-story steel framing K-12 school building will be analyzed based on the design loads and load combinations specified in ASCE-7: Minimum Design Loads for Buildings and Other Structures. The design loads in ASCE-7 are continuously updated to address the climate changes and new challenges, which will be reflected in the analysis to compare the building design criteria and structural capacities from the past two decades. The structural capacity will be evaluated as an emergency shelter/public assembly (Risk Category IV) during and post disasters, versus a regular school building (Risk Category II or III). Full live loads will be combined with the natural disaster loads to evaluate the school building capacity as a community resiliency hub. The results will be used to assess the structural resilience level of school buildings functioning as emergency shelters in natural disasters.

Tortional Effect in Vertically Mass Irregular RC Frame Structure under Response Spectrum Analysis

Abstract: The structures having discontinuity like distribution of mass, stiffness and geometry of the structure are termed as Irregular structures. Irregular structures contribute a large portion of urban infrastructure. The past earthquakes have shown catastrophic effect on the buildings with irregularities. It was seen that the buildings with irregularities are more prone to earthquake then the regular building. In the present study a special case of vertical mass irregularity are discussed. Six different models including three basic cases of buildings models i.e. vertically regular structure, vertically irregular structure and vertically irregular structure with shear wall at different position are taken for analysis by Response spectrum. It has observed that, the torsion, base reaction, displacement and modal load participation ratio in structure. This study exhibits effect of mass variation aspect of RCC structure

Comparative Study on Seismic Analysis of Multistorey Building Using STAD Pro - A Review

Abstract: This literature review provides a comprehensive analysis of the behavior of buildings with concave corners in earthquake-prone areas. The study emphasizes the impact of irregularities in building planning, particularly in concave corners, on the structural performance during seismic events. Findings from various research studies highlight the necessity for detailed and comprehensive analyses, including both linear and non-linear dynamic analyses, to accurately understand the behavior and response of such structures. The research underscores the significance of regular building configuration to enhance earthquake resilience, especially in regions susceptible to seismic activity. Buildings with concave corners are found to be more vulnerable to earthquake damage compared to structures with regular configurations. Additionally, larger structures and longer overhangs are shown to result in increased stress and pressure on the reentrant corner region. Overall, the literature review emphasizes the importance of further research in the field of concave corner irregularities to develop effective seismic design and mitigation strategies. A deeper understanding of the behavior and response of buildings with concave corners will contribute to the development of safer and more resilient structures in earthquake-prone areas. Comprehensive and advanced analyses are recommended to accurately assess the performance of such buildings and to establish guidelines for their proper design and construction.

AGDF-Net: Attention-Gated and Direction-Field-Optimized Building Instance Extraction Network.

Building extraction from high-resolution remote sensing images has various applications, such as urban planning and population estimation. However, buildings have intraclass heterogeneity and interclass homogeneity in high-resolution remote sensing images with complex backgrounds, which makes the accurate extraction of building instances challenging and regular building boundaries difficult to maintain. In this paper, an attention-gated and direction-field-optimized building instance extraction network (AGDF-Net) is proposed. Two refinements are presented, including an Attention-Gated Feature Pyramid Network (AG-FPN) and a Direction Field Optimization Module (DFOM), which are used to improve information flow and optimize the mask, respectively. The AG-FPN promotes complementary semantic and detail information by measuring information importance to control the addition of low-level and high-level features. The DFOM predicts the pixel-level direction field of each instance and iteratively corrects the direction field based on the initial segmentation. Experimental results show that the proposed method outperforms the six state-of-the-art instance segmentation methods and three semantic segmentation methods. Specifically, AGDF-Net improves the objective-level metric AP and the pixel-level metric IoU by 1.1%~9.4% and 3.55%~5.06%.

Design Demands of RC Buildings Due to Irregularities

The RC-framed building is one of the most common construction technique for seismic-resistant structures due to its ductile nature. However, the seismic performance of RC structures can be significantly influenced by different factors, irregularities being one of the most important aspect. Irregularities on buildings increase the lateral seismic forces and inter-storey drifts thus increasing seismic demands in the structural elements. Due to architectural or functional requirements, many times irregularities cannot be avoided even though such arrangements are discouraged in the building codes including the Nepal National Building Code (NBC) 105:2020. Although many studies have been performed to quantify the effects of such irregularities internationally, design effect has not been analyzed in the context of Nepal and NBC 105:2020. Therefore, this study aims to present the variation in design demand for RC buildings in different irregularities scenarios. Three buildings models exhibiting irregularities in torsion, stiffness, and diaphragm are taken and analyzed in Finite Element platform SAP 2000 and compared with a regular building in terms of storey drift, internal forces, etc. The final design of the structural elements shows that the design demand in terms of section size and reinforcements can be significantly influenced by the presence of such irregularities.

A Hybrid Artificial Neural Network—Particle Swarm Optimization Algorithm Model for the Determination of Target Displacements in Mid-Rise Regular Reinforced-Concrete Buildings

The realistic determination of damage estimation and building performance depends on target displacements in performance-based earthquake engineering. In this study, target displacements were obtained by performing pushover analysis for a sample reinforced-concrete building model, taking into account 60 different peak ground accelerations for each of the five different stories. Three different target displacements were obtained for damage estimation, such as damage limitation (DL), significant damage (SD), and near collapse (NC), obtained for each peak ground acceleration for five different numbers of stories, respectively. It aims to develop an artificial neural network (ANN)-based sustainable model to predict target displacements under different seismic risks for mid-rise regular reinforced-concrete buildings, which make up a large part of the existing building stock, using all the data obtained. For this purpose, a hybrid structure was established with the particle swarm optimization algorithm (PSO), and the network structure’s hyper parameters were optimized. Three different hybrid models were created in order to predict the target displacements most successfully. It was found that the ANN established with particles with the best position revealed by the hybrid models produced successful results in the calculation of the performance score. The created hybrid models produced 99% successful results in DL estimation, 99% in SD estimation, and 99% in NC estimation in determining target displacements in mid-rise regular reinforced-concrete buildings. The hybrid model also revealed which parameters should be used in ANN for estimating target displacements under different seismic risks.

Effect of P-delta on RC framed buildings with plan irregularities for wind

In recent times due to rapid population rise and the lack of open spaces, the demand for tall buildings especially in the urban areas ís increasing day by day. At the same point, the frequency and magnitude of extreme natural events are also trending up, due to which tall buildings are becoming vulnerable under lateral loading. So, while designing and analysing a high-rise, additional emphasis must be given on both the first and second-order loading effects on tall buildings which are essential to understand its response under lateral stochastic loading. P-Delta, a second-order effect that are mostly manifested in tall buildings when subjected under lateral sway. Besides, the shape of the plan also plays a significant role in it in terms of its regularity in shape. Structures with irregular plan are becoming widely visible and popular among urban and modern infrastructure for space management as well as aesthetics views. The current study is aimed to perform a comparative study of different RC framed buildings having geometric plan irregularities without P-Delta and with P-Delta using ETABS. The study is focussed to detect the effect that P-Delta has on the buildings with irregularity in terms of maximum displacement, storey drift etc. and draw the parametric deviation of the irregular buildings with the regular buildings having equal plan area subjected to wind as their lateral load. Additionally, the study is also enlightening the effect of bracing systems on buildings with irregularity with & without P-Delta.

Seismic Performance of Vertical Irregular Steel Frame Structure under Mainshock-Aftershock

Abstract: The majority of the structures are involved with architectural importance and it is highly impossible to achieve uniform structural properties in all directions. Hence earthquake resistant design codes considered it as irregular frames based on relative difference in the story properties. In many cases these irregularities are responsible for structural collapse of buildings under earthquake ground motions. The seismic response of buildings with irregular distribution of stiffness along the height may be differentfrom that ofregular building. Also, past earthquakes showed that structure may be subjected to sequence of ground motions but current codes do not have guidelines for such cases. It is considered that aftershock do not cause any more damage to damaged structure by the preceding mainshock ground motion. In this study steel moment resisting frame buildings are evaluated to understand the seismic response of vertical stiffness irregular frames subjected to mainshock-aftershock ground motions. The 9-story steel moment resisting frame building situated in Los Angeles is used in this study was originally developed as part of the SAC steel project. In this study soft and stiff storey case was considered at three different locations along the height, i.e., at bottom storey, mid-height storey and top storey. The single modification factor is used for irregularity. For comparison purpose dynamic properties of regular and irregular frames are kept same. Two sets of 6 records were selected representing a seismic hazard level of 2% and 10% probability of exceedance in 50 years respectively as mainshock. Two sets of 30 mainshockaftershock ground motion are considered for the study. These ground motions were developed using randomized approach. A non-linear time history analysis of regular and irregular building is carried out separately under mainshock and mainshockaftershock. The effect of building irregularity was studied for single storey modification at bottom storey, mid-storey and top storey with comparison to regular building. The comparison of a regular and irregular building is carried out in terms of maximum roof displacement and interstorey drift ratio. Also, comparison of frames under mainshock and mainshock-aftershock is done.

Response modification factor evaluation for vertically irregular MRF buildings

Most design codes evaluate the non-linear seismic performance of structures using the response reduction/modification factor (R). The value of R is sensitive to a variety of factors in terms of overall ductility and over-strength. In this work, actual R values were assessed for vertical irregularity cases for reinforced concrete bare buildings with moment-resisting frames (MRFs). A significant relationship between R and the vertical irregularity index, calculated from the relative stiffness between adjacent storeys, was derived. Three-dimensional numerical modelling was carried out for soft storey and setback irregularity scenarios using Etabs. Modal pushover analysis was used to obtain the inelastic seismic capacity. It was found that vertically irregular buildings have weak inelastic seismic capacities compared with regular buildings. So, before the design stage, R should be scaled down by 15–40% for single and combined vertical irregularity scenarios. Structures with a combined asymmetric setback with a soft ground storey were found to have the worst R value and R was sensitive to the vertical irregularity index (Vtm) that has R-squared of 80%. So, the vertical irregularity index can be used to specify the allowable vertical irregularity ratio, location and combination of vertical irregularities for each seismic zone.

Seismic Analysis of High-Rise Buildings Considering Aerodynamic Effect

High-rise buildings with irregular shapes are gaining popularity in creating vertical cities around the world. A high-rise building is a wind-sensitive structure and its shape plays a major role in determining wind loads, which usually govern the design of its lateral resisting system. Therefore, aerodynamic treatments on high-rise buildings must also be considered, because even a small amount of geometrical shaping modifications can provide considerable damping against wind loads which in turn disturbs the mechanism of the vortex shedding phenomenon. Computational fluid dynamic (CFD) simulations are currently an effective tool for the aerodynamic study of buildings in conjunction with wind tunnel investigations. This paper presents the analysis of a 50-storey and 100-storey building considering aerodynamic modifications, which is firstly achieved by creating a digital system of computational fluid dynamic (CFD) analysis of buildings with the different minor and major aerodynamic shape modifications and hence evaluating aerodynamic forces on the buildings, subsequently, the seismic assessment of a 50-storey regular and irregular building by response spectrum and time history analysis is also studied.

AELH-, CFD-, and ANN-based wind interference zone prediction of regular tall buildings

AELH-, CFD-, and ANN-based wind interference zone prediction of regular tall buildings

Dynamic climate-adaptive design: A key to realizing future-proof energy efficiency in building sector

Being vulnerable to climate change, building energy designs based on the present-time weather conditions might lose their efficiency over time and diverge from their initial designated performance. The idealistic approach to realizing lifelong energy efficiency accommodates building energy systems with not only drivers for survival from upcoming changes but also possibilities to thrive under new boundaries. Such a notion requires designers to step beyond the regular static-based building energy design mindset and move towards considering future uncertainties and variabilities due to the changing climate. In line with this need, the present study investigated the boundaries of climate change integration into building energy designs and proposed a conceptual framework that provides dynamic climate-adaptivity. Climate-adaptive designs, in any field, cannot be pictured without time-varying nature. Outlined framework encompassed such characteristic as its innate component and implemented it in a practical way suited for the building industry. A case-study building was studied based on this framework and compared with a conventional static-based energy-optimized design. Results indicated that the proposed framework has a strong potential in incorporating the variability of climate change into building energy designs and reducing energy demand by 23%, on average. Furthermore, it was concluded that static-based building energy designs are subject to losing their efficiency over time and are suboptimal in future climate boundaries.

A Fast Frequency Sweep approach for performance-based optimization of earthquake-resistant irregular large-scale buildings

Performance-Based Design (PBD) optimization of buildings subjected to seismic excitations has increasingly been applied to regular small-scale structural systems to minimize initial or life-cycle costs. Nonetheless, a comprehensive bibliographic survey reveals that studies dealing with irregular buildings are scarce, although they can present higher seismic vulnerability than regular buildings. Specifically, the PBD optimization of irregular buildings represented by large-scale finite element (FE) models, and considering dozens of discrete design variables, cannot be found to the best of the authors’ knowledge. Hence, this paper presents an original framework for the PBD optimization of irregular buildings subjected to seismic excitations, handling thousands of DOFs and dozens of discrete design variables. To relieve the computational burden, enabling the problem to be solved, a Model Order Reduction (MOR) strategy based on the Well-Conditioned Asymptotic Waveform Evaluation (WCAWE) approach is combined with a hybrid optimization algorithm, which integrates a local optimizer with a restart strategy. The former is employed to speed up the frequency-domain response, while the latter allows for tackling a non-convex and multimodal objective function with many discrete variables. The procedure is adaptatively devised to operate in a robust and fully black-box approach. The application case consists of a stiffness in-plane irregular H-shape building with 16,452 active DOFs and 34 discrete design variables. The proposed scheme largely reduces the computational burden, leading to speed-up factors (SUF) up to 19 times compared to direct frequency-domain solutions.

Universal Health Coverage in Iran: A Review of Strengths, Weaknesses, Opportunities, and Threats.

Universal health coverage (UHC) aims to provide access to basic health services with no financial constraints. In Iran, the major challenges to the implementation of the UHC plan include aggregation and augmentation of resources, something which could threaten the dimension of population coverage and health service delivery. Therefore, this study reviews the strengths and weaknesses of the internal environment as well as the opportunities and threats of the external environment in the UHC plan to help policymakers and decision-makers of the health system. In this review study, reputable databases were searched for all the relevant papers on UHC to collect data. After that, the strengths, weaknesses, opportunities and threats (SWOT) analysis was conducted to organize, collect, and analyze data. The SWOT analysis is a process that has 4 components and 2 dimensions. The 4 components are strengths, weaknesses, opportunities, and threats. In fact, strengths and weaknesses are considered internal factors and organizational features, whereas opportunities and threats are considered external factors and environmental features. The listed items were then categorized for clarification and transparency within the framework of the 6 building blocks of the World Health Organization (WHO). The relevant studies were reviewed to analyze the strengths and weaknesses of internal environments as well as the opportunities and threats of external environments. The necessary points for better planning and policymaking were then presented. The success of Iran's UHC plan can be guaranteed by regular capacity building, ongoing education, and empowerment of society in addition to improving intersectoral collaboration and acquiring political commitment to develop more effective and more accountable systems matching variable and dynamic health requirements.

Development of an approximate method for analysis of connected buildings considering soil-structure interaction

Bridges connecting high-rise towers are becoming popular due to functional, architectural, and connectivity reasons in addition to the structural benefits they provide. Two regular adjacent buildings will become irregular with respect to certain modes when rigidly connected with a reinforced concrete bridge. The analysis of connected buildings for lateral loads is often complicated as it depends on the dynamic properties of the connecting towers and bridge. The design procedure for regular buildings according to earthquake codes will no longer be acceptable for connected buildings. For a realistic solution, the superstructure-foundation-soil interaction must be considered as one compatible unit. The study presents an approximate method developed for the analysis of connected buildings considering soil-structure interaction. The actual building model with 3x3 bays and 10 stories as twin towers, with varying sizes of piles and the bridge, is modeled in ETABS and the structural response is obtained. An approximate model using a single tower with modifications of mass and stiffness coefficients at the level of connection is used to develop an analytical model in MATLAB. In each model, a fraction of the axial stiffness and mass of the bridge is considered from 0 to 20 at a regular interval of 0.5 and the closeness of the structural response to the actual is determined. The contribution of the stiffness and mass to be considered is varied and the closest match is determined. The study is repeated by varying the level of the bridge, diameter of the pile, and the width of the bridge from a single bay to three bays and inferences drawn.