Practice Periodical on Structural Design and Construction

The rapid depletion of natural building materials is mainly caused by the exponential increase in construction operations. The need for and inevitability of finding alternative building materials to partially replace traditional materials in construction are unavoidable. In this study, the idea of using pond ash and bottom ash as a partial replacement of fine aggregates in concrete is examined, and the effects of pond and bottom ash on the fresh and mechanical properties of concrete are investigated, as reported in the literature. Being affected by the coal burning system, the chemical and physical properties of pond ash and bottom ash vary across various sources and years of investigation. Many experiments have shown that bottom ash and pond ash can be used in the right proportions to provide workability and increased strength of concrete. The idea of turning a variety of waste into wealth to conserve essential green space is backed by nearly every academic. Again, the increased use of fly ash (FA) and pond ash (PA) as an alternative to river sand will reduce river sand extraction and ensure the long-term stability of a green river ecosystem.

Abstract

Two new design and certification methodologies have been developed to compute the reliability of façade access systems using simplified risk-based procedures. These methods consider uncertainties in the loads, load effects, and component capacities to calculate individual component probabilities of failure. These probabilities are then used to compute an overall system probability of failure, which can be used for both design decision making and system certification purposes. A worked example is presented to fully demonstrate the certification procedure.

Practical Applications

In this paper, reliable procedures to certify and design façade access systems are both presented and demonstrated. These methods determine the risk of failure for each element of a façade access system and then use these to determine the risk of system failure. This risk of failure can then be compared against the desired maximum risk for failure of the system. These approaches are useful for efficiently computing the approximate reliability of a façade access system, which can then be used to inform design, certification, planning, and/or operation decision making. These are intended to be practical approaches to determine the reliability of a façade access system. As such, the necessary steps and equations for these methods are discussed, and a fully worked example is presented.

Abstract

The response of RC frames with confined masonry (CM) walls is governed by the interaction between the surrounding RC frames and the confined masonry panels. This interaction will not only affect the structural integrity of the masonry walls but also significantly affect the failure mode of the RC frames compared to what they were originally designed for. This study investigates a simple engineering tool developed previously for infilled frames that are expressed by the relative stiffness and relative strength. To determine its validity to identify the ultimate failure modes of columns in RC frames with CM walls, the tool was calculated based on 48 laboratory specimens of single-story and single-bay CM frames tested by other researchers. Based on the obtained results, a modification to identify the ultimate failure mode of RC frames with CM walls is suggested. These experimental data were further used to develop a backbone curve of lateral response of CM frames vulnerable to fail in shear. The results of this study indicate that the proposed curve can satisfactorily represent the response of CM frames, with ranges of error in estimating the peak strength, residual strength, drift at peak strength, and drift at residual strength for all considered specimens based on proposed backbone curve of $-30\%$ to 33%, $-28\%$ to 54%, $-45\%$ to 89%, and $-35\%$ to 100%, respectively. Moreover, the proposed backbone curve is compared with a curve developed by other researchers, and it was found that the proposed backbone curve can better represent the experimental data. The maximum errors in estimating the peak strength, residual strength, drift at peak strength, and drift at residual strength for three of the specimens based on the proposed backbone curve are 11%, 16%, 67%, and 24%, respectively, while the maximum error in estimating these values based on the other researchers’ curve are 48%, 71%, 69%, and 75%.

Practical Applications

The shear failure observed in CM frames after earthquakes encouraged researchers to investigate the reasons of this brittle type of failure. Development of an engineering tool is essential to identify when shear failure can occur based on the geometry, material properties, and reinforcement detailing, and this was previously developed for infilled RC frames. This research modified this tool to be used for CM frames based on an experimental database. It is also vital to evaluate and predict the CM frames’ behavior under lateral loads. The proposed backbone curve is effective because it allows for the assessment of existing CM frames or the design of new confined buildings taking into consideration the gravity and lateral loads to determine the strength, deformation capacity, and ultimate failure modes.

Geopolymer concrete (GPC) is one of the best alternative options for conventional concrete due to its adequate mechanical and durability properties with the addition of a lower carbon footprint. This research presents the experimental results of using ground granulated blast furnace slag (GGBS), fly ash (FA), and silica fume (SF) as a binder and manufactured sand (MS) as a fine aggregate on fresh and hardened high-strength geopolymer concrete (HSGPC). Initially, 16 mortar mixes were prepared and tested for compressive strength to finalize solution/binder and sodium silicate/sodium hydroxide ratios for HSGPC. The different mix proportions for M70, M80, M90, and M100 were calculated and validated experimentally. The proposed mix design methodology achieved the maximum compressive strength as high as 104 MPa at 28 days, along with coarse aggregate and MS. The promising mechanical properties were observed at 28 days for all grades of concrete. The mechanism of strength increment was appropriately justified by microstructural analysis. The equations of split tensile and flexural strength in terms of compressive strength were compared with the previously proposed equations in the literature. Microstructural analysis of HSGPC revealed that the enhancement in mechanical properties creates a dense microstructure of different gel formations like calcium-silicate-hydrate (C-S-H), calcium-alumino-silicate-hydrate (C-A-S-H), and sodium-alumino-silicate-hydrate (N-A-S-H) gels in HSGPC. Finally, the environmental impact assessment in terms of carbon emission of HSGPC was evaluated. It is found to be 90% lower compared with conventional concrete.

Studies have shown that repairing damaged structures and rebuilding them after an earthquake, especially in densely populated cities, can impose severe financial and economic pressures on countries. To address this, rocking systems have been developed to improve the seismic performance of structures, which allow the rocking wall to engage in rocking motion while elastic devices provide self-centering and dissipate seismic energy, resulting in less structural damage and reduced repair costs. However, there are limitations concerning common rectangular-shaped rocking walls, including high use of materials and difficulty in controlling large displacements. This study investigated the use of modified rocking shear walls attached to 3- and 9-story moment-resisting frames by reducing the thickness of the wall, adding border elements in the form of dumbbells, and modifying the prestressing ratios of the posttensioning cables. The models were designed according to seismic codes and analyzed through nonlinear time-history analysis when subjected to 14 sets of modified near-field ground motions. It was concluded that the modified system reduced the amount of concrete used by 36% and 20%, increased the fundamental period by 19.3% and 26.6%, and increased the base shear by 8% and 20% in 3- and 9-story models, respectively. Moreover, the proposed method effectively reduced the overall interstory displacements in the midrise model by 11%, whereas the low-rise model had 8% higher interstory displacements. This indicates that the proposed method can be effective for deployment in mid- to high-rise buildings because it can control the upper floors’ displacements.

This work experimentally evaluated compressive strength and splitting tensile strength of cellular lightweight concrete (CLC) under varying strain-rate conditions. A novel artificial technique called multigene genetic programming (MGGP) was used in conjunction with the stepwise regression analysis to develop mathematical models that are efficient in predicting major strength parameters (compressive strength and tensile strength) of CLC under various displacement rates ($0.1–10\mathrm{mm}/\min$). In the observation, the MGGP-based models outperformed the regression-based models for predicting both splitting tensile and compressive strengths. The outcome of this study demonstrates that displacement rate and density have considerable impacts on both compressive and splitting tensile strength of CLC. With an increase in displacement rate from 0.1 to $10\mathrm{mm}/\min$, the compressive strength and tensile strength of CLC are found to increase by 87% and 116%, respectively. The proposed models would help to predict the strength parameters analytically with significant accuracy where experimental tests are not feasible to perform.

Recent studies have focused on investigating ultrahigh-performance fiber-reinforced concrete (UHPFRC) developed under normal conditions, but the majority involved the use of special filler aggregates. The effect of fibers, especially hybrid fibers, on the postcracking performance of UHPFRC developed under normal conditions has still not been investigated in depth. Toward this objective, this study investigated the behavior of a hybrid fiber mix in an optimized UHPFRC mix manufactured from locally sourced materials. Steel fibers, after being optimized by volume, were investigated for the effect of aspect ratio on the mechanical performance of developed UHPFRC. The UHPFRC with 3% hybrid fibers possesses high compressive strength (158.76 MPa), split tensile strength (26.52 MPa), and flexural strength (60.28 MPa). The hybridization of the fibers with low and high aspect ratio results in enhanced mechanical performance compared to a single aspect ratio. Long fibers lead to the highest toughness index of 32.60, followed by the hybridization of fibers at 24.95. Toughness indexes are also observed to be highest for long fibers and are comparable for hybrid fibers to reported valuable values. Hybridization of fibers leads to highest ductility indexes of 2.32 followed by long fibers at 2.13, indicating the energy dissipation capacity of normally developed UHPFRC is in good agreement with conventional UHPFRC.

Hybrid buckling restrained brace (HyBRB) is a new inspectable passive energy dissipating device which comprises of an axially load carrying prismatic steel core, a pair of steel restrainers, and high damping neoprene infill layers in between restrainer and core. In this study, influence of infill layer geometry on performance of HyBRB is investigated. HyBRB specimens are designed to facilitate restrained local buckling initially about weak axis and subsequently about strong axis at high axial core strain level. Three variants of HyBRB are tested under cyclic displacement protocol. Experimental results established that the hysteretic behavior of all three variants of HyBRB are stable with compressive strengths are comparable to the corresponding tensile strengths. Shear deformation in the infill layers enhanced damping in the HyBRBs in low axial strain level. Restrained local buckling about strong axis of the core helps to achieve enhanced energy dissipation capacity and effective stiffness in high axial strain levels. Continuous infill layers in HyBRB significantly enhanced equivalent damping factor (about 22%) as compared to that with the discontinuous infill layer (about 18%). However, all three variants of the newly developed HyBRB provide a mechanism for simple yet efficient energy dissipation.

Four specimens of a circular tubular structure with fin plate connections were load tested to failure and compared with the corresponding finite-element method (FEM) analyses. There have been no investigations of such a circular tubular structure, which is a basic module of a space frame, reported in the literature. The modes of failures, initial stiffness, first yield loads, and ultimate load capacities were studied. Comparison of results of the load tests and finite-element analyses based on first yield load of the circular tubular structure was made. A parametric study of the fin plate connections in a circular tubular structure investigated in the present study was carried out using finite-element analyses. The exploratory study seemed to suggest that the thickness and depth of the fin plate as well as the diameter and thickness of the vertical circular hollow section (CHS) were important parameters in affecting the behavior of CHS structures studied, but the length of the fin plate was not. The major principal stresses of the vertical CHS exceeded that of the fin plates. Four failure modes were observed in the load tests of the four specimens. The FEM analyses showed that attainment of the required load-carrying capacity of fin plate connections in a circular tubular structure was highly dependent on the thickness of the fin plate and the level of accuracy (workmanship) achieved in the fabrication process. The present exploratory study highlighted the importance of the need to implement a quality assurance and quality control measure to gauge the magnitude of eccentricity of the fin plate connection introduced during the fabrication process for each and every fin plate connection to ensure that the magnitude of eccentricity was within the tolerance spelled out in the contract documents. This also means that in the design of fin plate connections in circular tubular structures, the choice of the thickness of the fin plate must take into account the risk of this unavoidable geometric imperfection introduced during the fabrication process. The findings of the exploratory study provide a useful guide for the full investigation of the behavior of such fin plate connections of circular tubular structures.

The railway bridge over the Bhakra River is an open web riveted steel girder bridge between the Bareilly–Rampur section that belongs to the Moradabad division of India’s Northern Railway. Simulation-based fatigue life assessment of this railway bridge was carried out for full-scale train loading given by the Research Design and Standards Organization (RDSO). STAAD.Pro CONNECT Edition software was used to analyze the bridge, identify critical members, and calculate residual life for 25T-2008 loading at various speeds with stress bands of 5 and 10 MPa for a stress life–based approach. MATLAB software was used to find the number of repetitions corresponding to the stress history diagram. A linear elastic fracture mechanics (LEFM)–based approach was also applied to assess the remaining life of the bridge. Analysis showed that a smaller stress band should be used for precise bridge life. This study will be useful in the conditional health assessment of steel railway bridges using an S-N curve based approach as well as a fracture-based approach.

A three-dimensional (3D) model of a six-story building subjected to a surface blast is analyzed using the coupled numerical approach. The simulation incorporates the explosion process, shock wave propagation through air and soil medium, shock wave structure interaction, and structure response in a single model to study the soil–structure-interaction effect on the blast response of the building. The coupled analysis is implemented with the help of the coupled Eulerian–Lagrangian scheme. The study shows that soil type has a significant effect on the surface-blast-induced response of the building. Further, validity of the uncoupled analysis is investigated, as it takes much less computational time than the coupled analysis. The uncoupled analysis is found valid for greater standoff distance, while the fully coupled analysis is to be performed in the near blast situation.

To improve the precision of traditional response surface methods, an updated response surface method is proposed. Combining the updated response surface method and fmincon algorithm, the accuracy of the finite-element model of a certain prestressed concrete continuous beam bridge is improved using the data of in situ dynamic testing. First, on the basis of specific configurations of a certain prestressed concrete continuous beam bridge, three specific design parameters that need to be updated were preselected. Eigenvalues of 15 samples were calculated using the central composite design method. The response surface method was updated by obtaining the internal relationship between specific design parameters and response eigenvalues. Fifteen response eigenvalues were calculated by finite-element analysis. Using the lsqcurvefit algorithm, undetermined coefficients of the updated response surface model were calculated, and the updated design parameters and response eigenvalues were obtained using the fmincon algorithm from the MATLAB toolbox. Numerical examples show that the updated design parameters and response eigenvalues are reasonable when compared with original parameters. Using the updated response surface method and fmincon algorithm, the numerical model of a prestressed concrete continuous beam bridge was updated effectively.

The high strength of bamboo material cannot be fully utilized due to the failure of bamboo culm before reaching the ultimate strength values. This study focuses on the prevention of different failures caused due to shear, bearing (dowel embedment), and pull-out (tension) of bamboo culms. Bamboo culms are strengthened with hose clamps and adhesively bonded hose clamps, and the performance of the strengthened bamboo culms in terms of the load-carrying capacity and type of failure is evaluated. An experimental investigation was carried out on Bambusa balcooa bamboo species predominant in the Indian subcontinent, and a finite-element (FE) modeling procedure is presented for the same using ABAQUS software. It is found that hose clamps enhance the load-carrying capacity of bamboo culms by 10.19%, 32.57%, and 17.88% in shear, dowel bearing, and pull-out, respectively. Whereas, hose clamps that are adhesively bonded delayed splitting and increase the culm’s load-bearing capacity by 34.27%, 78.24%, and 51.08% in shear, dowel bearing, and pull-out, respectively, before failure. Using the validated FE models, a parametric study was carried out to study the influence of clamp thickness and clamp width on the load-carrying capacity and the failure modes of the specimens.

Abstract

The stereotomy (bricklaying pattern) of masonry arches is not only a characteristic of the architecture of these structures, but also an important revealing element of mechanical safety when degradations appear in the complex material of masonry. This paper presents the effect of randomness of this parameter on the bearing capacity of masonry arch bridges based on reliability of structures. Different mechanical models that are classically used for the analysis of the bearing capacity of masonry arches can support a reliability analysis. In this paper, a rigid block model and finite-element model are presented and compared. Then, focusing on the rigid block method, stereotomy has been integrated as a geometrical parameter influencing the mechanical behavior. To this end, the stereotomy function is presented as a parameter that can be influenced by the possible degradations affecting the blocks and/or mortar joints, thus justifying its randomness and consequently integrating it in a reliability study. The reliability study carried out in this work focused on the case of a single-span masonry arch bridge located in Morocco. The reliability analysis demonstrated the importance of joints orientation and the possible perturbations that it can undergo around the classical radial configuration. The effect of these perturbations is shown for the failure multiplier, which represents the bearing capacity of the studied arch.

Practical Applications

Masonry arch bridges are a heritage of great architectural and economic importance for many countries worldwide. This is due to the historical value of these ancient constructions, but also to their durability that allowed them to still fulfil their economic role. Nevertheless, the preservation of the safety of masonry arch bridges depends on a good maintenance approach that takes into account the different hazards affecting these constructions. The uncertainties affecting the geometry are among the hazards to be taken into account by the roadway and railway managers. In this paper, the authors study the effects of uncertainties related to the bricklaying pattern of masonry blocks on the mechanical behavior of the arch bridge. For this purpose, probability-based methods are applied in conjunction with mechanical calculation techniques. The results obtained highlight the importance of considering the stereotomy parameter, which represents the bricklaying pattern of masonry blocks in the arch in maintenance operations.

In this study, a novel solution is proposed to locally strengthen precast prestressed concrete (PPC) driven piles by wrapping them with glass fiber reinforced polymer (GFRP) composites at the end regions. To investigate the feasibility of the proposed solution, five full-scale square PPC piles were manufactured, among which two were strengthened with externally bonded bidirectional GFRP wraps at both ends. All piles were then driven in a sandy soil in a project site using a diesel hammer, while the driving-induced stresses were monitored using a pile driving analyzer system. Direct measurements of the tip strain at each hammer blow were also obtained by using a wireless embedded data collector technique. A static pile load test was also conducted on one of the piles. The field test results showed that the proposed GFRP-wrapping had no negative effect on the skin friction resistance of the PPC piles along their strengthened region. A close inspection of the exhumed piles also revealed that the pile’s tip remained intact during driving with no debonding between the GFRP wrap and the concrete substrate, demonstrating the great potential of the proposed strengthening solution in maintaining the integrity of the PPC piles during driving.

This study presents a novel investigation and comparison of the mechanical properties, specifically compressive strength (CS) and flexural strength (FS), of autoclaved aerated concrete (AAC) blocks using machine learning (ML) models: linear regression (LR), artificial neural network (ANN), and Gaussian process regression (GPR). The novelty lies in the utilization of ML techniques to predict the mechanical strength of AAC blocks, which have been prepared through a unique combination of materials including flyash (FA), construction and demolition waste (CDW), lime (L), cement (OPC 53), gypsum powder (GP), alkaline solution (AS), and free water (FW). Notably, various proportions of CDW are substituted for FA, and AS is employed as a substitute for aluminum powder (AP). Moreover, the curing process is innovatively conducted in an accelerated curing tank (ACT), deviating from conventional autoclaves. The experimental evaluation of CS and FS serves as the foundation for the development of the ML models, employing days strength, FA, CDW, L, OPC 53, GP, AS, and FW as input parameters. The performance evaluation metrics, including mean square error (MSE), root mean square error (RMSE), and coefficient of determination (${\mathrm{R}}^2$), demonstrate the superiority of the GPR model in predicting CS and FS. To augment the comprehensive understanding of AAC block performance, additional experimental tests are conducted to analyze block density (BD), water absorption (WA), and drying shrinkage (DS) of AAC specimens. Furthermore, the study encompasses an optimization process to derive an optimal AAC formulation by considering the diverse range of data sets, primarily focusing on maximizing CDW content, CS, and FS, while minimizing FA content and BD. Overall, this research contributes novel insights by showcasing the proposed ML models’ applicability for CS and FS prediction in CDW-based AAC blocks. The experimental investigations conducted on the AAC specimens enhance the current understanding of material performance, further emphasizing the originality and significance of this study.

This manuscript first presents the development and then the implementation of simple design aids that allow bridge engineers to quickly estimate idealized moment–curvature relationships for circular concrete columns in compliance with current specifications by using a pocket calculator or a spreadsheet. The design aids were developed in a normalized domain so they are particularly convenient for preliminary stages of design when the engineer may want to know the nonlinear static (pushover) response of circular columns for selected reinforcement ratios (longitudinal and transverse) and axial load levels. The formulation is applicable to column diameters up to 2.44 m (8 ft), longitudinal reinforcement ratios ($\rho$) from 1% to 3%, spiral reinforcement ratios (${\rho }_s$) from 0.5% to 2.5%, nominal concrete compressive strengths ($f_c^{\prime }$) from 28 MPa (4 ksi) to 56 MPa (8 ksi), axial loads from $–0.5f_y\rho A_g$ (tension) to $0.5f_c^{\prime }{A}_g$ (compression), and grade 420 MPa (60 ksi) reinforcement. Application examples are presented to illustrate the use of the design aids and to validate the obtained results with commercially available software.

This paper investigates the effectiveness of local strengthening using textile reinforced mortar (TRM) jackets on the global response of reinforced concrete (RC) frames under gravity and lateral cyclic loadings. Finite element analysis (FEA) was employed to develop and validate an RC bare frame model against an experimental study in the literature. Consequently, four TRM strengthening configurations were applied considering the column’s confinement and strengthening of joints and beams. With the aim to attain a ductile behavior of the frame, the selection of each configuration was based on the predicted failure of the preceding strengthening arrangement. A parametric study was performed to investigate the effect of the number of layers, length of TRM jackets, textile orientation, and distributed load values. Finally, the FEA models were compared with traditionally and noninteracting masonry infilled frames from the literature. By evaluating the local retrofitting influence on the global response of the frames, the strength and stiffness enhancements were marginal as compared to the control model. Local measures were more effective in the frame’s post-peak response, hence, enhancing the ductility of RC frames. The TRM application to the beam-column joints resulted in substantially higher energy dissipation as compared to the model with no joint upgrading. When comparing the TRM local strengthening method to the global technique using infilled walls, the TRM retrofitted models showed similar energy dissipation to that of noninteracting masonry infilled specimen and lower values than those of the traditionally infilled frame.

Abstract

Composite slab construction has become one of the most viable options for overcoming today’s challenges in the construction industry. The cohesion weakness between the main two components of such slabs—the concrete surface and profiled metal decking sheet—has been considered one of the problems limiting their wide applications. This research attempts to use the results of both experimental and numerical investigations in conjunction with the existing design methods to propose a design chart for profiled metal decking slabs. An experimental program was conducted on six full-scale specimens to investigate the effect of both the spacing of shear connectors and the ratio of the reinforcement mesh on the structural and bond behavior of the slabs. Following that, a three-dimensional (3D) finite-element (FE) model was developed to simulate the structural behavior of the slabs, and its reliability was evaluated in light of the experimental results. After that, the shear bond strength between the profiled metal decking sheet and the concrete was analytically evaluated using both the well-known m–k and partial shear connection (PSC) methods to verify the experimental results and clarify the limitations of using those methods. Ultimately, the verified FE model was adopted to find out the effect of the clear span–slab thickness ratio ($L/ts$) on the behavior of the slabs. The experimental as well as numerical findings showed that the ultimate capacity of the profiled metal decking slab is dependent on the spacing of the shear connectors, the ratio of reinforcement mesh, and the clear span–slab thickness ratio.

Practical Applications

The research attains a practical application to improve the behavior of composite concrete slabs because they give maximum protection for lives in the event of earthquakes due to supporting the concrete slab from sudden and momentary collapse. The idea still needs to be developed, but for now, one can say that the use of a metal sheet installed in the bottom of the concrete slab acts as an additional steel reinforcement, and this is capable of increasing imposed load on the concrete slab as well as supporting it externally from sudden fracture.

Integrated project delivery (IPD), an emerging collaborative-oriented project delivery system, is considered an advanced solution to the limitations of traditional project delivery approaches. Research on factors that have influenced IPD implementation has recently got broad attention. One of interests is cultural barriers as one of the main obstacles to implementing IPD. However, culture is a broad concept that involves the organizational shared values, beliefs, and behaviors, and many aspects of this concept might shape practices and behaviors to adopt IPD implementation. This research aims to fill the knowledge gap by analyzing cultural factors through organizational change frameworks. It identifies the elements that are important in successfully implementing IPD. A conceptual framework is proposed as a scaffold to inform the importance of cultural factors. The framework was drawn from organizational change and the organizational development models. Cultural factors in the framework were classified into two categories: managerial-level factors (communication and integration, reward system) and member-level factors employee (involvement, readiness to change). The framework was validated using a partial least squares structural equation modeling (PLS-SEM) technique. Data was collected using a survey questionnaire from 128 participants. Results indicated that employee involvement is the most influential factor strongly correlated with successful IPD implementation. Factors of communication, integration, and readiness to change were positively correlated with IPD implementation. Surprisingly, the reward system had no significant relationship with IPD implementation. Plausible reasons are discussed in further detail. Research contributions include a comprehensive exploration of IPD viewed under the lens of organizational change, analysis of the fundamental factors of culture for project delivery to initiate change, and study of cultural factors in organizations that align well with IPD implementation requirements.

Ryukyu limestone, which is distributed widely in the Ryukyu Islands, Japan, may be unsuitable for use as coarse aggregates for concrete because of its high water absorption rate and low strength. This study experimentally investigated whether it is possible to reduce the water absorption rate of crushed Ryukyu limestone aggregates (CRLAs) by impregnating them with phenol resin, and investigated the mechanical characteristic of concrete using the CRLAs impregnated with phenolic resin as coarse aggregates. Repeating the impregnation with phenolic resin twice can reduce the water absorption rate of CRLAs to 3.0% or less. Furthermore, the compressive strength and splitting tensile strength of concrete utilizing the impregnated CRLAs as coarse aggregates can be similar to the corresponding strengths of concrete using ordinary crushed limestone aggregates.

Blast analysis of a storage container inside a liquefied natural gas (LNG) facility needs rigorous finite element analysis (FEA). This paper presents a detailed method of nonlinear dynamic analysis of LNG storage vessels subjected to blast load. The explicit dynamic solver of the commercially available FEA software Abaqus is used to perform the analysis. The finite element models of the LNG storage tanks include the static fluid pressure and internal pressure. Constitutive material models include strain-rate dependent elastic-plastic material effects. Based on the results of FEA, recommendations are made for safe practice of maintaining the structural integrity of vessels subjected to vapor cloud explosion (VCE).

Currently, digital technologies provide engineers with the ability to improve quality control in civil engineering and construction. In this industry, structural quality control aims to prevent deviations that may occur in the assembly of the structure, to guarantee compliance with the essential requirements for its operation. In this context, an attempt was made to learn whether the application of digital technologies, particularly use of the laser scanners, is a resource that facilitates quality control procedures, making them digital and more reliable. In the presented case study, the methodology involved the use of a laser scanner in the quality control of the assembly of a steel structure of an industrial building. Thus, after the study on technologies associated with the automation of geometric object checks, with the use of the computational tools and digital laser survey technologies, the structural elements assembled in situ were analyzed. The main results this study allow us to conclude that the use of the digital laser scanner survey technologies contributes favorably to the automation of geometric quality control procedures in the assembly of steel structures.

In the most severe seismic zones, the majority of earthquake-resistant structures are constructed using in-plane shear walls with frames in India. RC wall-frame buildings exhibit an increase in structural stiffness resulting from the combined behavior of flexure and shear under seismic loading. In addition to this, the nonlinear behavior of RC wall-frame buildings is crucial to investigate. In the present study, 8- and 15-story RC wall-frame structures with various shear wall configurations were designed using the direct displacement-based design (DDBD) approach considering life safety (LS) performance state. The fragility curves were generated using the nonlinear static pushover analysis. The seismic vulnerability was calculated using fragility curves. The performance of RC wall frames under seismic loading was studied using the interstory drift ratio and the future collapse probability of the structure with reference to damage indexes. RC wall-frame building of shear walls located in the center of the inner panel performed exceptionally well in both mid- and high rise because the probability of severe damage is 0.4% for 8-story and 0.7% for 15-story buildings; and the probability of collapse is 0.1% for both, indicating that structures designed using DDBD satisfied the performance state. The present investigation contributes to quantifying the seismic fragility and vulnerability of RC wall-frame buildings and establishing an initiative for seismic fragility-based design of DDBD-designed RC wall-frame buildings using the fragility curves.

Locomotives and trains—as well as the tracks on which they run—emit noise and vibrations. Vibrations are transmitted through the subsurface to the nearby building, where they can be felt directly or are heard as secondary airborne noise. Recurring vibrations can impact the health of people living and working in the nearby areas. This article describes the application of under-ballast mats (UBM), an elastic spring installed under the railway ballast, as an effective measure for vibration mitigation. The particular novelty is the use of UBMs for vibration mitigation with heavy-haul trains, which have high axle loads of about 33 t. This article firstly presents the process of assessing the specific conditions of the customers site in Mexico. Secondly, it looks at the steps in choosing a suitable UBM and performing design calculations. Finally, the vibration measurements are discussed to assess the performance after UBM installation. The measurements show a vibration reduction of 15.5 dB at 63 Hz and 19.9 dB at 125 Hz. The perceptible vibration peaks inside the building were reduced by 44%. The result confirms the suitability of UBM for vibration mitigation on heavy-haul lines and thereby reducing the impact of vibrations on people’s health. This consequently fosters acceptance among railroad operators and developers.

A shallow earthquake ($M_{\mathrm{W}}=5.8$; $\mathrm{depth}=10\mathrm{km}$) hit the Mirpur City of Pakistan at 16:01 local time on September 24, 2019. The earthquake severely damaged RC structures, low-rise brick masonry structures, and various other civil infrastructure facilities. The close location of seismic stations to the damaged area provided the opportunity to assess the seismic response of the buildings subjected to real ground motions. This study aims to provide insight into the failure modes during a field reconnaissance trip following the 2019 Mirpur, Pakistan, earthquake. Damage procedures and causes were determined by analyzing the specific responses of the site to the ground motions and comparing them to the spectral intensity of the ground motions recorded in the vicinity. Insights gained from the damages were then used to identify specific design requirements or general design principles. The findings suggest strong relevance of the vertical component of the Mirpur, Pakistan, earthquake with excessive axial force demands in masonry piers in addition to various inherent structural properties such as soft-story mechanisms. Poor construction practices and nonseismic detailing combined with deficient structural materials induced major seismic damages in brick masonry and reinforced concrete structures. It is concluded that damage from short-period ground motion originating at shallow depths can be exceptionally serious for unreinforced brick masonry (URBM) structures, even with low-magnitude ground accelerations. Dominant failure modes observed in this investigation suggest excessive axial compression or shear-axial compression, shear-flexure cracking, slab rotations, foundation settlement, and soft-story mechanisms. The damage survey highlighting the observed failure modes serves as a useful tool for researchers and practitioners in formulating seismic-resistant design guidelines.