Practice Periodical on Structural Design and Construction

The construction industry is essential for the economic prosperity of any nation. However, the construction workforce encounters numerous challenges stemming from various factors, including the dynamic and cyclical nature of construction operations. These challenges have led to undesired outcomes such as shortage of skilled employees and increased employee turnover rates. To overcome these undesired outcomes, construction companies have started to look for innovative strategies aimed at empowering their employees. The goal of the present study was to identify and statistically examine the most effective strategies for achieving employee empowerment, focusing specifically on the perspective of employees themselves. To achieve the study goal, a list of strategies from prior studies believed to be desired for empowering construction employees were identified from existing literature. A survey questionnaire was developed and sent to frontline construction employees, and 114 responses were collected. After collecting the responses, descriptive and inferential statistical analyses were performed. The findings identified 12 strategies perceived to be effective for empowering construction employees and provided statistical evidence to support the effectiveness of these strategies. In particular, equitable payment, nondiscrimination policy, transparency, and professional development/training were identified as particularly impactful in advancing employee empowerment in construction. By implementing the identified strategies, construction companies are expected to cultivate a positive work environment that fosters employee engagement, improves productivity, and ultimately contributes to overall organizational success. Future research and industry initiatives can build upon these findings to further enhance employee empowerment and well-being in the construction industry and facilitate the implementation of these strategies throughout the industry. The present study contributes to the understanding of employee empowerment in construction by highlighting the strategies perceived as highly effective by construction employees.

Important secondary structures such as pipes may experience damage and become cracked during earthquakes. This not only may cause the piping to lose its functionality, but also may lead to secondary hazard such as fire if the piping carries flammable fluid supplies. This study investigated the effectiveness of base isolation for the safety of buildings with secondary structures when subjected to real earthquakes and pulse-type ground motions. The coupled equations of motion for multiple-degree of freedom (MDOF) secondary systems supported on MDOF fixed-base and base-isolated structures are developed and solved using Newmark’s integration method. A lead–rubber bearing called the N-Z system is used as an isolation system to improve the performance of the coupled system subjected to ground motions. The variation in moment and shear at the base, the top floor absolute acceleration and bearing displacement, and the interstory drift ratio (IDR) for these structures under different ground motions is computed. The effect of the shape of the force–deformation loop of the N-Z system on the response of the base-isolated structure is studied under the variation of important system parameters such as isolator yield displacement and yielding strength of the N-Z system. It is found that the base-isolation technique is effective for response control of structures under both type of ground motions. It is concluded that the N-Z system with lower yield strength can effectively control the dynamic response of both primary and secondary structures. In addition, maintaining a lower yield displacement is a suitable design choice for the isolator. Therefore, designing the N-Z system with a yield displacement of 30 mm is recommended.

In the current study, the high-volume replacement of river sand (20%, 30%, 40%, 50%, 60%, 80%, and 100%) by pond ash in cement mortar was considered using a $1:3$ volumetric mix proportion to evaluate the engineering properties, sustainability aspects, and cost of mortar mixes. The compressive strength, tensile bond strength, and adhesive strength increased by 30%, 21%, and 24%, respectively, at 30% replacement and were in line up to 60% replacement as compared with the reference mix. However, the drying shrinkage was observed to increase with volume replacement of river sand. The life-cycle assessment of mixes containing pond ash showed reductions in the environmental impacts. Four different scenarios were considered on the basis of the preference advantage of the indicators. Considering the engineering properties, sustainability aspects, and cost as the primary indicators, the gray clustering analysis showed that the mix with 60% volume replacement exhibited the best performance among the mixes under Scenario S-1, while TOPSIS and VIKOR showed that the mix with 50% volume replacement exhibited best performance under Scenario S-1. Overall, the comparison of all scenarios showed that the mix of 60% pond ash had the best performance followed by the mix with 50% pond ash, irrespective of the multicriteria decision-making techniques and preference advantages.

Abstract

The design of suspension bridges predominantly emphasizes wind and earthquake loads, frequently overlooking the consideration of extreme events in the design stage, thus posing a threat to bridge safety. The purpose of this research is to spread awareness among engineers for identifying weak zones in a bridge and to provide a new insight into how much damaging the blast loading could be for the long-span suspension bridges if not designed properly under the blast loads. The current dynamic analysis procedures for bridges under blast loads are complex and computationally expensive, making them unsuitable, especially for long-span bridges. To address this, a simplified dynamic analysis approach is proposed to assess the structural response and extreme limit state of suspension bridges exposed to blast loads. The method involves a bilayer solution: blast loading is modeled as nodal loads, and the structural aspect is represented by a three-dimensional (3D) fishbone skeleton finite-element (FE) model. Time-history simulations of blast loads are conducted for various bridge locations and explosive sizes. The parametric dynamic analysis reveals that the tower top node is the most vulnerable location in the suspension bridge under blast loads, which potentially exceeds the stress limits of nearby main cable elements and triggers the zipper-type progressive failure of the entire suspension bridge. Similarly, blasting at the deck nodes nearby tower on the main span side as well as on the side span side significantly amplifies axial stresses in nearby suspenders and the main cable, i.e., demand-to-capacity ratios of C18 and C19 surpass unity under BS4-6W and BS4-8W, respectively confirming that the failure state has reached for C18 and C19 under medium- to large-sized explosives. Therefore, it is recommended that the maximum demand-to-capacity ratio for all bridge components under medium- to large-sized explosives shall be kept below 0.8 to ensure the safety of the entire structure under extreme limit state.

Practical Applications

This paper provides a methodology to investigate the structural redundancy of suspension bridges under extreme limit state by providing a bilayer solution: the blast aspect, which is simulated as nodal loads on the bridge road surface and the structural aspect, is simulated as a 3D fishbone skeleton FE model. The implicit dynamic analysis approach is adopted parametrically by considering variable explosive weights and locations. For each blast scenario, the time-history of nodal loads is applied to various locations of the bridge considering small- to large-sized blasts. From a practical viewpoint, this study is relevant to develop comprehensive understanding of the dynamic behavior exhibited by long-span bridges when subjected to extreme loading scenarios. In essence, the aim is to explore the benefits and applicability of this research to the design of long-span bridges under blast loading conditions. The simplified approach presented in this paper, along with the corresponding bridge response results, allows a bridge design engineer to analyze a suspension bridge effortlessly. This method eliminates the need for intricate computations required to assess blast pressure over a solid bridge model, enabling a straightforward visualization of the anticipated behavior under blast loading. The research serves a crucial role in checking and verifying the extreme limit state, in addition to assessing the serviceability and ultimate limit states according to AASHTO’s requirements. For existing suspension bridges, the study proves beneficial in formulating a comprehensive blast-resistant plan through retrofitting and strengthening identified weak zones. Consequently, this research holds practical significance, serving as a foundation for further exploration and investigation into the effects of blast loading on various types of long-span bridges.

Green concrete utilizes industrial waste resources as fine and coarse aggregates, to partially replace cement in concrete using supplemental cementitious materials. The primary goal of the present study was to explore the acid durability of green concretes with different compressive strengths of 30 and 40 MPa. In green concrete, fly ash and ground granulated blast furnace slag (GGBS) were adopted as SCMs, and quarry dust (QD) and recycled coarse aggregates (RCA) were adopted as replacements for fine and coarse aggregates, respectively. The acid durability assessment was carried out by immersing concrete cubes in ${\mathrm{H}}_2{\mathrm{SO}}_4$ and HCl solutions followed by residual compressive strength comparison. For comparative study purposes, the same grades of ordinary concrete were prepared, tested, and subjected to similar acid exposure. The microstructural investigation was also accomplished by employing field emission scanning electron microscopy (FE-SEM) analysis and energy-dispersive X-ray spectroscopy (EDS). It was found that concrete with 30% GGBS and 20% fly ash and the remaining 50% ordinary portland cement as cementitious materials along with 40% QD and 30% RCA as aggregate replacements gives adequate compressive strength and performs better in aggressive environments as compared to traditional concrete. These mixes were found to have denser microstructures with silica-rich, calcium silicate hydrate (C-S-H) gel.

Double-skin tubular columns (DSTCs) are promising modern columns with concrete sandwiched between fiber-reinforced polymer (FRP) and steel skins. Typical concentrated and localized failure modes in DSTCs can be constrained or delayed when stiffened inner steel tubes are used. DSTCs with circular cross sections are better investigated in the literature than scarcely studied square shapes, especially with variations of stiffened inner steel tubes. This study examined the nonlinear confined concrete behavior in stiffened DSTCs with square-shaped glass FRP as outer skins and stiffened steel tube as inner skins. The documented test results on 26 DSTCs were used to formulate a new analysis-oriented, axial stress–strain model for confined concrete. Primary model-formulation parameters were evaluated using a genetic algorithm (GA)–driven error minimization. A detailed parametric study was then performed on square DSTCs by incorporating the proposed stress–strain constitutive relationship for confined concrete in nonlinear finite-element analysis. The variations used in the parametric study included the shape of the inner steel tube (circular versus square), unconfined concrete strength, and flat-stiffener geometry characteristics (i.e., quantity, configuration in terms of thickness versus the number of stiffeners for similar total cross-sectional area, and its cross-sectional dimensions). Analytical results were finally used to propose a new load-bearing equation for estimating the axial load capacity of square DSTCs having stiffened inner steel skins of circular or square shapes. The proposed formulation showed better accuracy (about 2% on average and 14% maximum disparity with refined ultimate axial load capacities of DSTCs used in this study) than the existing prediction models.

To address the environmental impact of greenhouse gases in cement production, incorporating cement substitute materials is crucial. However, the slow degradation of discarded tires poses environmental challenges, making burial or incineration unsustainable. This study explores the integration of discarded tires as crumb rubber in concrete and the use of silica fume as a cement substitute. Experimental methods, coupled with neurofuzzy systems, were employed to predict the mechanical properties of the resulting modified concretes. In the experimental approach, silica fume replaced cement at weight percentages of 0%, 10%, 12%, and 15%, while crumb rubber substituted sand at volume percentages of 0%, 10%, and 25%. Compressive and flexural strengths were evaluated at seven, 28, and 90 days, with tensile strength assessed at 28 days. The neurofuzzy system utilized six inputs—cement, gravel, sand, silica fume, water–cement ratio, and sample age—to forecast tensile and compressive strength in silica fume-containing concrete. Similarly, six inputs—cement, gravel, sand, crumb rubber, water–cement ratio, and sample age—were used to predict flexural and compressive strength in rubber-containing concrete. The findings reveal that the inclusion of silica fume enhances the mechanical properties of concrete, while the introduction of crumb rubber diminishes these properties. Specifically, a quantitative analysis demonstrates the positive impact of silica fume on the strength and contrasting effect of crumb rubber. The neurofuzzy system exhibits remarkable accuracy in predicting tensile and compressive strength for silica fume-containing concrete and flexural and compressive strength for rubber-containing concrete.

This paper reports a comprehensive study on the performance of the in-plane behavior of masonry walls. The use of wire rope and neoprene as a method for reinforcing existing masonry walls is proposed in this paper. The performances of the five walls with and without reinforcement were evaluated using experimental tests and numerical models. The first specimen was an unreinforced masonry wall (witness wall), which was tested under simultaneous cyclic and vertical loading. This wall was modeled using a simplified micro-modeling approach in the standard finite element software, Abaqus. A finite element (FE) study verified the experimental results to predict the in-plane behavior of masonry walls. Furthermore, to investigate the in-plane behavior of nonload-bearing walls in masonry structures, another sample with dimensions and a lateral loading protocol similar to the first sample was modeled by removing the vertical load. After a comprehensive understanding of the failure modes and damage mechanisms, the unreinforced load-bearing wall was strengthened using steel cables and neoprene in a cross-diagonal reinforcement pattern, whereas the unreinforced nonload-bearing wall was strengthened using steel cables and neoprene in a vertical pattern. The details of the modeling and wall construction, test setup, testing procedure, and results are described in detail in this study. The results indicated that the energy absorption capacity of the unreinforced walls was extremely low, and the effects of narrowing and asymmetry in the hysteresis curve were observed. The proposed retrofitting system increased the lateral load capacity, initial stiffness, deformation capacity (reducing the residual deformation), and energy dissipation capacity and created a self-centering response in the wall.

In this paper, some recent analytical expressions including those of codes for shear strength calculation of reinforced concrete (RC) beams without and with stirrups are discussed and verified against experimental data available in the literature. An analytical expression proposed by the author is also introduced and discussed. Two different sets of experimental data were analyzed: one for beams without stirrups composed of 719 data and the other one for beams with stirrups composed of 152 data. Comparison between experimental data and analytical results showed that all of the analytical expressions of international codes are conservative in prediction. The proposed equation gives the same grade of accuracy of the other existing analytical expressions for the prediction of experimental data, and it is derived by a mechanical approach. Comparison shows that although most of the analytical expressions give safe and conservative results, more effort is still necessary to reduce the high scatter of prediction of all the expressions used here, especially for beams without stirrups.

Pervious concrete (PC) has become more popular in recent years as a solution to the runoff problem. PC has a large number of voids, allowing surface water to flow freely through its structure. Strength and permeability are crucial design factors for PC, but there has been limited research examining their mutual relationship. In the studies, constant head (CH) and falling head (FH) permeability test methods were used to find the coefficient of permeability of the PC because there is no standard method for measuring it correctly and precisely in laboratory conditions. Also, the experiment aims to investigate the influence of various aggregate grading (single, two, and three particle size gradations) and cement-to-aggregate ($\mathrm{C}/\mathrm{A}$) ratios (0.20, 0.25, and 0.33) on the compressive strength (CS), split tensile strength (STS), flexural strength (FS), permeability, and porosity of PC while maintaining a constant water-to-cement ($\mathrm{W}/\mathrm{C}$) ratio of 0.34. The findings demonstrate that three particle size gradation mixes give higher CS, STS, and FS as compared to single and two particle size gradations. The porosity–permeability relationship of PC was analyzed using experimental results, and the FH and CH permeability tests were compared to determine the more reliable method. The investigation also established a novel model between the CH and FH methods, while examining the correlation between porosity and permeability.

Abstract

Effective communication is essential in the construction industry to ensure coordination and collaboration among stakeholders for successful project outcomes. However, traditional communication methods often fall short in meeting the industry’s complex demands, often leading to delays, errors, and increased cost. This emphasizes the need for innovative communication solutions, including augmented reality (AR), to help improve communication practices in construction. By integrating virtual elements onto the real-world, AR enhances visualization, information sharing, and collaboration; these are some of the benefits of leveraging AR to ease communication challenges between project stakeholders in various locations. AR tools and applications include remote collaboration, virtual site visits, and real-time progress tracking. However, the successful adoption of AR in construction requires use-based guidance to inform users on effective AR utilization, including guidance on which tools may be feasible and beneficial in a given context. Previous studies exploring the use of AR as a communication tool have revealed different factors affecting the efficacy of using this technology. The objective of this paper is to build on the previously reported factors affecting the efficacy of AR for communication on live construction sites to create a guiding framework for implementation of technological tools and methods supporting successful AR implementation. This framework is developed based on rounds of modified Delphi panels that comprise panelists that have previous experience in using AR for communication, and panelists without experience with AR. In capturing both user types as Delphi panelists, the authors ensure that the developed framework is practitioner-friendly and can guide effective decision-making.

Practical Applications

This paper serves as a resource for site construction practitioners seeking to integrate augmented reality (AR) as an effective communication tool throughout the construction process. By offering a practical guiding framework, the paper facilitates the implementation of AR for interaction purposes between on-site and off-site personnel, reforming communication channels. Construction professionals can leverage AR technology to conduct inspections, address inquiries, and collaborate efficiently, bridging the gap between those physically present at the construction site and those working remotely. Within the framework presented in this paper, the implementation of AR is facilitated through a breakdown of each supporting tool, accompanied by specifications and considerations for their effective utilization in varying site conditions. By offering users a clear understanding of the specifications of each tool, such as their capabilities, features, and technical requirements, the framework empowers construction practitioners to make informed decisions tailored to their specific project needs, ensuring that practitioners can select the most suitable AR solutions for tasks like inspections, collaborative discussions, and problem-solving. This approach not only enhances the overall efficiency of communication but also maximizes the utility of AR technology in diverse construction scenarios, ultimately contributing to the successful integration of AR into the construction workflow.

Research work of this study focuses on the seismic soil-structure interaction (SSSI) analysis of a base isolated nuclear building (NB) of the Indian pressurized heavy water reactor (IPHWR) under the action of coherent ground motion using the frequency domain approach. The seismic isolation of NB is achieved by installing lead rubber bearings (LRBs) below the raft. The base isolated NB is subjected to SSSI analysis in the frequency domain in order to take the influence of soil-structure interaction into account. LRB base isolators are numerically simulated as spring elements by assigning iterated equivalent linear stiffness. The seismic analysis of base isolated NB is performed using a conventional approach of fixed base analysis and the frequency domain approach of SSSI analysis to evaluate the effect of inclusion of SSSI on NB structures’ performance. This study also evaluates the implication of modeling isolators by assigning constant isolator stiffness as well as assigning equivalent linear stiffness to account for its nonlinear behavior under seismic excitation. Seismic responses in terms of in-structure response spectra and seismic displacements at representative locations of NB substructures are studied. The outcome of the study showed (1) base isolation of NB of IPHWR is achieved successfully by bringing down spectral accelerations and relative structural displacements of NB structure at target frequencies; (2) the conventional approach of fixed base boundary condition and assigning constant isolator parameters derived at isolator design displacement underestimates the structural responses in terms of spectral acceleration, frequencies, and displacements; (3) the conventional fixed base analysis approach fails to capture the spectral amplifications along its height at the fundamental frequencies of the various structure of NB; (4) discounting the SSSI effect along with equivalent iterative isolator parameters underestimates the structural responses marginally under horizontal excitation; and (5) the SSSI effect works like an isolation in the vertical direction and leads to reduced spectral accelerations in the vertical direction.

The accurate prediction of residual compressive strength (RCS) of concrete plays a critical role in assessing concrete constructions’ safety and structural integrity following exposure to elevated temperatures. Existing ensemble models exhibit RCS prediction capabilities, yet they are constrained by their opaque nature. This research endeavors to develop an intelligible model for RCS by employing five ensemble machine-learning models, namely, random forest (RF), adaptive boosting (AdaBoost), gradient boosting (GBoost), light gradient boosting (LGBoost), and extreme gradient boosting (XGBoost), and integrating Shapley additive explanations (SHAP) to ascertain the precise importance of each input variable in forecasting the RCS of concrete under elevated temperature conditions. The input variables encompass concrete type, compressive strength, aggregate type, water-cement ratio, heating type, heating rate, maximum core temperature, and cooling type. Model performance is appraised using established performance metrics such as mean absolute error (MAE), mean squared error (MSE), root-mean squared error (RMSE), and coefficient of determination ($R^2$). The analytical results exhibit the efficacy of employing machine-learning models in accurately predicting the RCS of concrete under elevated temperature conditions. Among the implemented models, XGBoost demonstrated the highest performance, yielding an $R^2$ value of 0.876, closely trailed by the LGBoost model at 0.871. The SHAP analysis elucidates the crucial role of core temperature, water-cement ratio, heating rate, and compressive strength in determining the RCS of concrete.

Concrete-filled fiber tubes (CFFT) are gaining prominence as a feasible alternative to traditional materials for a variety of structural applications. However, research on structural performance of CFFT beams is still scarce. This paper presents a finite-element (FE) analysis of CFFT beams validated by experimental results from literature. Then, a parametric study investigating structural performance of post-tensioned (PT CFFT) beams was conducted using 34 FE models using ANSYS nonlinear FE software program. The parametric study results showed that both normal-strength concrete (NSC) and high-strength concrete (HSC) filled PT CFFT exhibit identical nonlinear responses. Increasing the prestressed and non-prestressed reinforcement ratio significantly improved the overall performance of PT CFFT beams. Placing the PT tendons at the bottom of PT CFFT beams enhanced the cracking, yielding, and ultimate load-carrying capacities by 7.98%, 12.32%, and 9.03% for NSC-filled PT CFFT beams, respectively. Doubling the axial stiffness of the tube laminate structure increased the ultimate load, energy absorption capacity (EAC), pre-yielding stiffness ($K_{pre}$), and post-yielding stiffness ($K_{pos}$) by 18.5%, 12.15%, 9.21%, and 8.2%, respectively for NSC-filled PT CFFT beams. Beams with straight PT tendons exhibited increased cracking, yielding, and ultimate load capacity by 10.85%, 14.60%, and 13.58% more than those with curved-profile tendons. The ductility of PT CFFT beams is more sensitive to the amount of prestressed reinforcement ratio and concrete strength has a minimal effect on the structural performance of PT CFFT beams.

This paper presents the results of experimental testing of block masonry prisms and wallettes under uniaxial compression. The compressive load was applied in a direction perpendicular or parallel to the bed joints. Masonry prisms and wallettes were tested in the former direction, whereas only wallettes were tested in the latter direction. No influence of mortar strength or block thickness was observed on the cracking and failure patterns of specimens of similar type, although material crushing and spalling was marginally influenced by block strength. The cracking load for the assemblages tested normal to the bed joint was nearly 90% of the peak load capacity and higher as compared to 70% of the peak load capacity for the wallettes tested parallel to the bed joints. Similar load capacity and elastic modulus were observed for the prisms and wallettes tested normal to the bed joints. Whereas the strength for the wallettes tested parallel to the bed joints was 49%–83% less compared to those tested normal to the bed joints, their elastic modulus was nearly 25% higher. The experimental strength and strain values were compared with the existing analytical methods, which correlated well.

Steel plate girders are susceptible to web buckling due to slender web. This phenomenon creates an undesirable failure mode and limits their ultimate load capacity. The use of fiber-reinforced polymer (FRP) composite materials offers a good prospect of strengthening the slender web of plate girders to avoid web buckling. This paper presents the details of experimental testing of steel plate girders with nonrigid end posts. These girders were tested in three-point bending. The end shear panels of the girders were strengthened by glass FRP (GFRP) pultruded section stiffeners or glass fiber fabric composite. GFRP stiffeners were applied either vertically or along the compression diagonal in the shear panel. All strengthened panels failed by web shear buckling associated with a breakdown of the employed strengthening scheme. It was found that the shear capacity of the panel remained unchanged by replacing the steel stiffener with GFRP stiffeners in the end panel. The critical buckling load of the strengthened panels increased up to 44% compared to the unstrengthened panel. The shear capacities of the panels strengthened by the glass fabric composite and diagonal GFRP pultruded section were the highest and similar to each other. Both these panels resisted a 50% larger shear compared to the unstrengthened panel. The positions of the plastic hinges in all tested panels were the same due to the same ratio of panel length and depth of the web.

Abstract

Road infrastructure development in Indonesia has increased the use of long-span prestressed concrete I-section (PCI) girders for bridge structures. However, these girders have instability issues during construction that resulted in multiple failures between 2017 and mid-2018. To address this problem, engineers compiled a standard guideline for erecting long-span PCI girders that includes three recommendations: a lifting point or lifting frame, a dapped-end girder, and artificial stiffeners. In late 2022, despite the initial effectiveness of the guideline, a video revealed that PCI girders were still vulnerable to failure despite strict adherence to the guidelines. A subsequent study reviewed the guidelines and revealed that not all the guidance was effective. The study emphasized the importance of standardized bracing at the supports. Therefore, it is necessary to revise and improve the guidelines to prevent similar failures in the future.

Practical Applications

The process of erecting long-span prestressed concrete I-section (PCI) girders, which are more than 40 m long, is risky and can lead to toppling and collapsing. The main cause of this risk is the presence of lateral imperfections, which are limited to length or span of the girder $(\mathrm{L})/500$ (maximum) due to construction tolerances and the lateral stiffness being relatively small. Therefore, the process of erection must be carried out carefully and purposefully. To reduce the risk of accidents, a standard guideline for erection (SGE) was created. However, although the SGE (2018, 2021) has successfully reduced accidents, failures still happen. There are weaknesses in the SGE that need to be corrected. There are two critical risk stages during the erection of a PCI girder: the hanging and seated conditions. Using a lifting frame, according to the SGE (2018, 2021), is correct for the hanging stage. However, the seating procedure in the SGE needs improvement. It is vital to ensure that the strength of the bracing at the supports is standardized and installed correctly before removing the lifting crane. The reasons for this recommendation are explained in this paper.

The building façade is a vital component of a building’s structure and can play a significant role in safety, structure stability, energy efficiency, and aesthetics. Façade issues and failures are increasingly occurring in various buildings and cities. Some of these issues have caused safety incidents with fatalities to the occupants and nonoccupants. Nonoccupant incidents occur in façades located close to the public right away. This has led multiple agencies to implement inspection programs and regulations that the property owners shall comply with to avoid safety incidents. Despite these regulations, façade failures and safety incidents remain an issue, with various root causes, which could be due to insufficient original design documents, construction procedures, loading, or structural aging. This case study will discuss possible façade defect types and locations caused by soil, foundations, temperature changes, wind, and seismic. It will also discuss how to identify defects in various areas of the structure, including bearing and nonbearing exterior walls. In addition to these findings, those should be reported in detail with priorities to ensure effective urgent procedures are in place to avoid incidents. An example of a New York façade inspection program is discussed, and the reporting procedure is discussed with a fatal case study. In 2015, falling pieces of terra cotta caused the death of a two-year-old child; this incident led city officials to adopt changes in inspection requirements and procedures. In conclusion, gaining knowledge about the causes of defects, their location, and proper inspection and reporting procedures are crucial to public safety. This benefits not only the property owner but also the public, all trades involved in new project construction, inspectors, and officials to help avoid safety incidents.

The construction industry, characterized by unique challenges such as working at heights and using heavy equipment, has turned to unmanned aerial systems (UASs), frequently known as drones, to mitigate workplace hazards, improve safety, and enhance productivity. While numerous benefits claimed, application UASs in construction introduces unique safety challenges. The objectives of the present study are (1) to identify risks associated with the use of UASs for construction operations based on a review of existing literature, and (2) to present the identified risks to industry professionals and practitioners using hypothetical case study examples. The study findings indicate that risks associated with the use of UASs in construction can be classified into four categories: operational errors and safety hazards, privacy intrusions and security risks, mechanical and technical failures, and regulatory and legal considerations. After identifying the risks, three hypothetical examples are carefully developed and presented in collaboration with aviation safety experts to help industry people better comprehend risks associated with the use of UASs in construction. Each case study delineates hazards that could emerge on a construction site and explains the connection between these hazards and the utilization of UASs. The presented case studies also recommend risk mitigation strategies and best practices for using UASs for construction operations. The present study contributes to practice by aiding construction companies in risk awareness, safety training, and risk mitigation for UAS applications in construction.