Practice Periodical on Structural Design and Construction

This paper presents an experimental study on the strengthening of rectangular timber beams under monotonic loading. Both flexural and shear behavior of the specimens was studied. A total of five timber beam specimens with identical cross-sections were prepared. The first three specimens had a long span (3 m), whereas the remaining two had a short span (1 m). In order to obtain the benchmark parameters for flexural and shear behavior, one beam specimen from each span group was tested without adopting any strengthening measures. The long beam specimens were tested under four-point loading (for flexure) and the short ones under three-point loading (for shear). One of the long beam specimens was strengthened with mild steel plates bolted on the tension and compression sides. The last long beam specimen was strengthened with a carbon fiber reinforced polymer (CFRP) laminate adequately bonded on the tension side only. The other short beam specimen was strengthened with self-tapping screws in different detailing arrangements on the tension and compression sides to strengthen the specimen against horizontal shear. The performance assessment of all specimens was done on the basis of their peak load resisted, load versus midspan displacement, stiffness response, and failure mode. Last, the theoretical strengths of the specimens were quantified and were compared with the strengths obtained during the tests. It was observed that all strengthening measures adopted improved the targeted flexural and shear performance of the beam specimens. However, the performance improvement achieved was proportional to the cost involved for each strengthening measure adopted.

The adoption and utilization of technology for quality management (QM) processes and procedures is an efficient and effective tool to improve project performance, service life, and cost. Studies using existing and emerging technologies for QM in highway construction have found better results compared with those using conventional or traditional procedures. However, the extended use of these technologies in paving operations in the highway construction industry is limited due to stakeholders’ aversion to innovation. This study identified and assessed the usefulness of QM technologies used in highway pavement construction, identified the benefits of using these technologies, and examined the criticality of various barriers that prevent wider implementation. A survey was conducted among professionals with advanced knowledge of QM in the highway construction industry in the US. Findings showed that managing the quality of roadways in highway construction relatively uses low technology, regardless of the relatively high perceived usefulness. This study identified the device accuracy concerns, cost of the technology, and incompatibility of technology with existing practice as the major barriers. This research provides helpful insight for stakeholders in the highway construction industry and manufacturers involved in QM. The findings of this study will help to create a seamless process that enhances the adoption and implementation of technologies within QM processes.

Globally, cold-formed steel (CFS) construction is gaining popularity as an alternative to traditional methods of construction. However, there is a need for robust design specifications for each structural component and material used in the CFS construction practice. One material that is largely being used in the CFS construction process is the sheathing board for wall panel construction. However, as per the authors’ knowledge, there is no consistent criteria or specification for the selection of the sheathing board used in the construction. Besides, there are also no guidelines on parameters to be considered while selecting the sheathing material. Therefore, this paper aims to provide suggestions to select the appropriate sheathing based on the purpose and application of the sheathing. The interdependent parameters that influence the failure of the sheathing board connections such as type of screw, presence of washer, number of sheathing screw connections, edge/end distance, the failure mode of the wall frame studs, and geometry of the frame studs are discussed in the present study. The failure characteristics of four different sheathing boards are examined with the interdependent parameters. In addition, four different screw types are examined for better holding capacity and desired mode of failure. Furthermore, the suitability of existing recommendations for sheathing board requirement and installation methods are investigated. The suggested selection criteria for the sheathing boards are based on the various failure modes observed and the practical issues encountered in the CFS frame construction.

Eyebars commonly were used as tension members in steel truss railroad bridges, frequently installed in sets of two or more. Eyebars were favored by engineers because they (1) were easy to fabricate, (2) were faster to erect than other shapes, and (3) minimized secondary stresses by allowing freer rotation at joints. Research was conducted to gain a better understanding of the effects of excessive wear on the eyebars and connecting pins of a 110-year-old truss railroad bridges. Eyebar responses to live load were field tested. Strain and accelerometer readings were taken from four different types of passenger trains and at various speeds. Results indicate that different eyebars between the same two panel points frequently were loaded neither simultaneously nor equally. Adverse results of this phenomenon include development of excessive bending and shear stresses in pins, higher axial stress in some bars, and often extreme vibration of bars.

In this paper, nonlinear finite element analysis (FEA) was used to investigate the behavior of fiber-reinforced polymer (FRP) retrofitted steel beams subjected to static and fatigue loadings. Under static loading, damaged and undamaged steel beams were retrofitted with carbon FRP (CFRP) to examine the effect of bond length and transverse anchorages on flexural behavior and failure modes. Under fatigue loading, damaged control, basalt FRP (BFRP), and aramid FRP (AFRP) retrofitted steel beams were analyzed to predict their fatigue life. The CFRP laminates provided an increase in the flexural capacity for the undamaged and damaged beams by approximately 1.7 and 3 times, respectively, as compared to their counterpart control beams. The effective FRP laminate bond length under static loading condition was found to be $2/5$ of the simply supported beam length. Furthermore, with the addition of anchorages, the flexural capacity was increased by 1.5 times under fatigue loading, a regression analysis was performed to generate new S-N curves, and formulas were proposed to predict the fatigue life of BFRP and AFRP strengthened steel beams.

The installation of guardrails around a roof perimeter is an efficient way to protect construction workers against falls from heights, provided the guardrails are strong enough to arrest a fall. A guardrail’s strength relies heavily on its fastening to the roof parapets, and an improper fastening could lead to unsafe guardrails. This article investigates the in situ strength of temporary steel guardrails installed on the flat roof parapets of two existing buildings, respectively built in 2008 and 2013. Thirty-six strength tests were conducted on three different guardrails and four different parapets, considering different methods of fastening the vertical posts to the parapets and varying the fastening hardware. The results show that some guardrails are not easily installed on smaller roof parapets, which could lead to improper installation on some work sites. Fastening using only one plane of the parapet often resulted in guardrails failing before reaching the regulatory strength requirement. Fastening using two planes of the parapets gave satisfactory results in comparison, and that should be the preferred fastening method to guarantee workers’ safety.

Ductility is a desirable trait in an otherwise brittle concrete which is conventionally achieved via methods like introduction of steel reinforcement. While thin spray-on liner (TSL) is a material used in underground support systems to enhance the strength and ductility of rock and shotcrete, its application in concrete is a promising prospect. The study in this paper was conducted to observe the effect of application of Polyurea TSL on the flexural properties of unreinforced and lightly reinforced concrete slabs of varying strengths applied with varying thicknesses of Polyurea. The study used three-point flexural tests on slabs of uniform dimensions, simply supported on all sides, until failure or limit of test setup. Deflection was measured underneath the slab midpoint via a linear displacement sensor. Comparative analysis indicated that for the same strength and steel reinforcement, Polyurea application was significantly associated with an increase in stiffness, peak load, yield load, ductility, and energy dissipation in the specimens. Increasing Polyurea thickness also produced the same trend in the observed parameters.

Modified cold-formed steel (CFS) load-bearing wall-panels under consideration consist of a stud (C-section), track (U-section), and sheathing. Self-drilling screws are used to attach sheathing to the CFS frame. It was observed during various experimental testing that the behavior and strength of the CFS wall-stud changes in the presence of sheathing under axial loading. The present paper investigates the efficacy of a handy tool through analytical and semianalytical models, i.e., the differential equation of equilibrium (DEEq) method for a lipped C-section with continuous elastic supports and the constrained and unconstrained finite-strip method–direct strength method (CUFSM-DSM) by obtaining load factors through an elastic buckling analysis carried out using the CUFSM Tool, version 4.05, respectively, for the evaluation of the axial strength of sheathed CFS. In both the methods, the bracing provided by sheathing to the stud is assumed as spring. The predicted results by both methods are compared with observed strengths of short, intermediate, and long sheathed CFS wall-studs from the experimental database. Results demonstrate a good agreement with the experimental results. For the first time, an attempt is made to compare both the mathematical models to predict the axial strength of the CFS walls. The results presented in this paper demonstrate that the semianalytical tool may be used effectively for the design of a load-bearing sheathed-CFS wall panel.

This paper deals with the influence of transverse reinforcement (TR) in the joint panel on the behavior of RC beam-to-column moment-resisting connections. For this purpose, a numerical study is conducted on different beam-to-column connections by means of a validated model implemented in the finite-element (FE) software ABAQUS version 6.14. The investigated connections exhibit joint shear failure that may be accompanied by the yielding of beam flexural reinforcement. In this study, the effects of two major variables are assessed: the amount of TR and its layout on the seismic behavior of the connections. The results are expressed in terms of load-displacement curves, the ultimate failure mode of the connections, and stress distribution in the TR of the joint panels. According to the analysis results, TR does not significantly improve the ultimate strength of the connections whose governing failure mode is joint shear failure. However, TR can enhance the nonlinear deformation capacity of connections, especially those that exhibit joint shear failure accompanied with yielding of the beam flexural reinforcement. Moreover, the utilized layout for the shear reinforcement in the joint panel can improve the ultimate strength and the deformation capacity of the connections. The observations show that the induced stress in the TR of the joint panels does not necessarily reach the yield strength of the steel reinforcement up to the ultimate failure of the connection.

Past research has revealed that a sliding isolator with variable curvature (SIVC) can alleviate the resonance phenomenon that is likely to occur in a conventional friction pendulum system (FPS) due to its constant isolation frequency. Despite that, the use of SIVC systems is restricted to research purposes due to the nonavailability of a convenient modeling and analysis approach. The present study proposes a universal simplified modeling and analysis approach using the finite-element analysis software SAP2000, which can effectively simulate the behavior of four well known SIVC systems. Selecting the frequency variation parameters (FVPs), the effect of FVPs on the performance structures isolated by a variable frequency pendulum isolator (VFPI), variable curvature friction pendulum system (VCFPS), conical friction pendulum isolator (CFPI), and polynomial friction pendulum isolator (PFPI) have been studied under varied ground excitation by using the proposed modeling approach. Afterward, these chosen FVPs have been used to compare the effectiveness of SIVC systems under varied ground excitations for isolator parameters. The results indicate that VFPI more effectively controls the structural response than other SIVC systems, but it may show excessive sliding displacement for earthquakes having 4–6 s time-period long waves. Whereas in these types of earthquakes, CFPI and PFPI can effectively control the sliding displacement, but VCFPS fails to serve its design purpose for other earthquakes. The overall behavior of a structure isolated by VFPI remains more effective than one isolated by other SIVC systems for a wide range of earthquakes, especially for those earthquakes that have 0.1–4 s time-period waves.

This paper describes an investigation into the use of advanced manufacturing techniques for the creation of a new class of intermeshed steel connections that rely on neither welding nor bolting. The project detailed herein lays the groundwork to transform the steel building construction industry by advancing the underlying science and engineering precepts for intermeshed connections created from precise, volumetric cutting. The proposed system enhances the integration between design, fabrication, and installation. Fully automated, precise, volumetric cutting of open steel sections poses challenges regarding the load-transfer mechanisms and failure modes for intermeshed connections. Implementation of the intermeshed connection would cause a discontinuity in the beam; therefore, the effects of such a configuration on the behavior of the steel frame are investigated in the current paper. Load resistance and design of these connections are also explored with physical tests and finite element modeling to investigate the mechanics of intermeshed connections, including stress and strain concentrations, fracture and failure modes, and connection geometry optimization.

Concrete being one of the most extensively used material worldwide, the ecological influence of the manufacture of the raw materials for concrete is substantial. The scale of the problem makes it essential to examine other sources of raw materials to minimize the consumption of available natural resources. Since more than 70% of the bulk of conventional concrete consists of aggregates, maximizing the use of alternate/waste materials brings remarkable benefits such as a decrease in the demand for natural aggregates and saving energy costs related to natural aggregate production and conveyance. India, the second-largest consumer of crushed aggregates in the world, is making great strides in using waste/recycled materials as aggregates in pavement construction. Every year, millions of tons of reclaimed asphalt pavement (RAP) are being produced from the repair and reconstruction of existing roads. If this waste material can be reused without much processing in the construction of new pavements, it could be a great alternative to natural aggregates. This paper is intended to examine the flexural fatigue behavior of RAP-based concrete with and without steel fibers. The study considers varied proportions of RAP content (0% to 30%), fiber content (0% and 1%), and stress levels (0.9, 0.8, and 0.7). A total of 96 prismatic samples were examined under static and flexure fatigue load. The frequency for the fatigue loading was kept at 2 Hz, maintaining a stress ratio at 0.1. The results indicate a decrease in flexural fatigue life with an increase in the RAP content at all the stress levels. However, there is a substantial enhancement in fatigue life when steel fibers are added to RAP-based concrete. The results show that two-parameter Weibull distribution is the best fit for modeling fatigue life variation. The fatigue strength (at a survival probability of 0.9, corresponding to two million load repetitions) decreased by 9%, 18%, and 23% for RAP contents of 10%, 20%, and 30%, respectively. The addition of fibers enhanced the fatigue strength of RAP-based concrete by 50%–65%.

Offshore structures are mainly associated with the oil and gas industry given that globally, nearly one-third of the oil and gas extracted worldwide comes from offshore sources. This situation is likely to continue to rise over the coming decades because of abundant deposits of oil and gas still present in the oceans and society’s dependency on hydrocarbon fuels. Regardless, offshore wind shows promise and continues to rise at an exponential rate because it provides means for decarbonization while contributing to economic growth in many countries. As such, wind continuos to be a leading solution against climate change globally. To ensure that a structure will fulfill its function, fatigue design is crucial to ensure an adequate service life because it is responsible for more than 80% of structural failures, most of them catastrophic and without warning. This work aims to evaluate environmental loads and fatigue analysis in a jacket-type platform located in the North Sea. Wave data scatter has been provided, and using Morison’s formula, the loads on the structure were used to achieve an applicable normal loading force. Then, a static and a dynamic fatigue analysis for the offshore jacket-type structure under consideration are evaluated and compared.

The force-resisting ability of joints in a timber framed structure has direct implications on the overall response of such systems to various actions, thereby governing the integrity and safety of these constructions. Experimental investigations conducted previously in this regard have been directed mainly at a particular joint type with no focus on exploring the structural performance of various connection profiles common in timber construction. Moreover, regarding the development of reliable design guidelines, fewer studies have been reported from a numerical perspective with an effort to refine the joint detailing by optimization. Therefore, in this research, following the results of tensile testing on various T-shaped nailed-only and adhesive-cum-nailed joint configurations, the observed experimental behavior was numerically simulated in ABAQUS. Finite-element (FE) models post validation were employed to carry out parametric studies on developing numerical data over a wider range by extrapolation. Different values of tenon length, tenon width, and tenon thickness were used to analyze the effects on stress distributions and various performance parameters of mortise-tenon joints. Similarly, the influence of varying tongue slopes and tongue thicknesses on the performance of dovetail-halved joints was also investigated. Additionally, FE analysis outcomes were employed to check the accuracy of the strength prediction equations in recognized national standards, which revealed unconservative design strength estimation in mortise-tenon joints, whereas overly conservative results were obtained in the case of dovetail-halved joints. Therefore, suitable correction factors were proposed for improved, less scattered, and more reliable predictions using national design guidelines.

Detailed micromodeling (DMM), macromodeling, and multiscale modeling (MM) as a transitional solution between the two have been extensively used in the last years to model masonry. However, most previous works are based on an advanced theoretical background and/or require a user-defined subroutine, which may restrict their application in engineering practice. This paper proposes a practical and ready-to-use alternative to model and analyze small- and large-scale masonry using DMM and MM. To this end, brick–mortar interfaces were modeled using surface-based cohesive behavior; concrete damaged plasticity was used to model the nonlinear behavior of brick, mortar, and homogenized masonry. These constitutive models have already been implemented in ABAQUS software version 6.14. Mechanical characteristics of the homogenized masonry were derived from simple numerical tests conducted on a representative volume element. Numerical analyses were validated by comparison with experimental results of a confined shear test. It was shown that the DMM provides high accuracy in the simulation of the failure mechanism. The proposed homogenization technique for the MM, on the other hand, provides a satisfactory degree of accuracy with a significant computational cost savings. Both techniques can be used to predict the behavior of masonry at different scales.

Many times, existing RC flat slabs must be retrofitted to enhance their structural performance and service life. Among other retrofit techniques, concrete flat slabs can be strengthened with a top thin layer of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Since UHPFRC is a relatively expensive material compared to conventional concrete, an optimized investigation regarding the location and thickness of the UHPFRC layer may be necessary. This study examines the punching shear performance of isolated RC flat slabs retrofitted with various layouts of UHPFRC. Two optimal retrofitting configurations are proposed and evaluated using three-dimensional (3D) nonlinear finite-element analysis, where both regular concrete and UHPFRC are simulated using a combined damaged plasticity–based model. The model is verified by analyzing previously tested slab–column connections from the literature. Then the predictive capability of the model is further verified by conducting parametric studies to investigate the effect of varying the thickness and area of the UHPFRC layer on the punching shear performance of the slabs. The maximum shear resistance, deformation, and crack propagation patterns of the composite slabs with different thicknesses, areas, and orientations of the UHPFRC layer are examined. The increase in thickness of the UHPFRC layer increases the punching shear capacity. However, the displacement at the maximum resistance decreases when the thickness of the UHPFRC layer increases. The use of a UHPFRC layer only on the critical areas of a slab can be more effective and economical since the amount of UHPFRC is reduced and the ductility of the slab is increased.

A simple graphic procedure for the optimum design of elastomeric seismic isolation devices is proposed. Starting from the design requirements concerning a base-isolated building, such as the device’s stiffness, maximum displacement, and vertical load, as well as the code checks on the device, the procedure allows defining the optimum values of the mechanical and geometrical parameters, such as rubber shear modulus, diameter, and thickness, and the number of rubber and steel layers. In more detail, the procedure allows for first identifying the ranges of the geometrical characteristics through a graphic representation of code checks in terms of the rubber’s diameter and volume, and then their specific values that allow one to obtain the optimum solution according to the design requirements for any fixed values of the mechanical characteristics of the materials. The graphic representation represents a suitable tool to better understand the role and influence of the different checks. The procedure can be easily automated by means of a computer code.

This paper addresses the application of support fixity condition of column bases in computer structural analysis and design of steel frames. All structural analysis software require input data to model the frames. Supports and connecting points are identified by joint or node numbers, members are identified by member numbers, and so on. The column bases are identified as support joints, and the degrees of freedom of all support joints must be specified. Most programs provide a default support condition as fixed, meaning fixed against all six degrees of freedom. The six degrees are displacement and rotation in the $x$-, $y$-, and $z$-directions. A release command is used to release the restraint in any specified degree of freedom. It has been found that some engineers in some sectors of industry have been using incorrect column base support conditions for major steel frames, specifying pinned supports instead of the fixed supports in all their designs for years. This is equivalent to assuming that plastic hinges (full plastic moment) had already formed at the bottom of all columns before the frames were even applied with any loads. The results were safe design, but grossly overdesigned because the entire elastic range of moment resistance at all column bases were ignored. This paper describes the fixed and pinned supports and demonstrates with typical drawings and pictures of fixed and pinned supports commonly seen. Force distribution at typical anchor steel base plate (fixed support) is given with equation for applied moment. Test results for moment resistance of anchor base plates (fixed supports) are referred to. Several examples of actual major structures that were designed using a fixed-base connection and their life-long integrity under actual sustained service loads are given. Understanding of this paper should lead to a safe and economical design of steel structures.

This article investigates the effect of flexural reinforcement and ultrafine steel fiber on the punching shear of reactive powder concrete (RPC) slabs with different thicknesses. Ten RPC slabs and two normal-strength concrete (NSC) slabs were cast and tested with dimensions of $520\times 520\mathrm{mm}$. According to test parameters, these slabs were arranged into three sets. These parameters were the percentage of ultrafine steel fiber, presence/absence of flexural reinforcement, and thickness of the slab. All slab specimens were simply supported along the four edges and concentrically loaded by a square plate with dimensions of $70\times 70\mathrm{mm}$. The experimental results indicated superior and higher performance for RPC slabs compared with NSC slabs in which the punching shear resistance of RPC slabs increased by 78.8%, 92.5%, and 100.8% for RPC slabs containing steel fibers of 1%, 1.5%, and 2%, respectively, as compared with NSC slabs with the same thickness. Also, the presence of flexural steel reinforcement in the slab resulted in a higher ultimate punching shear strength compared with the similar slab without flexural steel reinforcement. Moreover, with increasing the slab thickness, the ultimate punching shear increased significantly and the ultimate deflection decreased as the flexural rigidity of the section increased. Finally, the results showed that it is possible to produce thin RPC slabs with 2% microsteel fibers and without flexural reinforcement to able to sustain the ultimate load, which are comparable with reinforced and nonreinforced normal concrete slabs, which is very crucial for designers who need to reduce the reinforcement amount required with beneficial effects on the cost and self-weight reduction for many structural applications.

Magnetorheological (MR) dampers have the ability to mitigate natural hazards for structures due to their high energy dissipation features with low power demand. This feature has made the MR damper one of the most popular semiactive damping devices. The present work validates the performance of a single-story reinforced concrete (RC) frame using a reduced scale 10 kN capacity multiple coil MR damper that has recently been developed by the authors. To conduct this test, MR fluid is synthesized and the proposed multicoil MR damper was designed and fabricated. Three RC frames were cast and tested using a loading frame with a capacity of 50 kN. This frame was subjected to earthquake excitation with MR damper placed diagonally at 0 A current, 3 A current, and without MR damper for a better comparison. The comparative performance indicated the reductions in displacements, increase of forces, and changes in crack patterns. The proposed semiactive damper can, therefore, be used effectively as a seismic resilient device in reducing the structural responses in the regions of moderate to high seismicity.

Seismic performance of elevated liquid storage tanks, considering soil–structure interaction (SSI), is investigated. The effects of considering SSI on the peak seismic responses, as well as on the seismic fragility of elevated tanks, are presented. A range of soil stiffness, representing very soft soil to hard rock, is considered in the present study. The effectiveness of base isolation technique in enhancing seismic performance of elevated liquid storage tanks is also evaluated. Furthermore, the effects of various parameters—e.g., slenderness ratio of the tank, stiffness of the staging, and natural period of the isolator—on the seismic performance of elevated tanks are studied. Peak responses and seismic fragility of the elevated tanks for two possible configurations of the base isolation system are examined: (1) isolator between staging and foundation, and (2) isolator between the tank and staging. In the present study, it is shown that the seismic fragility of tank structure largely depends on soil stiffness along with staging stiffness. Moreover, regardless of the configuration, the isolation system is observed to be effective in enhancing the seismic performance of the elevated liquid storage tanks.

In this study, a new type of rocking concentrically braced frames called rocking zipper-braced frame is developed. In the proposed system, zipper columns are added to improve the seismic performance of rocking concentrically braced frames. In these systems, rocking behavior lets the system lift up during earthquakes and then the post-tensioned bars that were utilized at the midbay will return the system to its initial state. Using zipper columns and the rocking behavior improve the seismic performance of the system in terms of uniform distribution of story drifts, which results in less structural damage. In other words, zipper columns decrease the damage concentration by redistributing unbalanced force over the frame height. In order to investigate the seismic performance, four different systems including concentrically braced frame, zipper-braced frame, rocking concentrically braced frame, and rocking zipper-braced frame were designed with various frame heights, and nonlinear time history analyses were performed using OpenSees version 2.0.0. under near-fault records. Different seismic responses such as story and roof drifts, residual story and roof drifts, top brace force, column uplift, cable force, and base shear were considered. The results present that adding zipper columns along with rocking behavior enhance the seismic performance of the rocking systems. However, this system is limited in height because of the need for larger top-story braces. So the proposed system is appropriate in low- and midrise buildings.

The main objective of the present paper is the application of a design method, traditionally used for medium- and large-diameter piles, to nongrouted hollow steel bar micropiles with very small diameters. The compressive resistance of this piling system, which is generally used for underpinning works, can be controlled during installation. The adopted analytical design method is based on the results of cone penetration tests to calculate the resistance of the micropiles under compression. Thanks to the availability of field data from micropiles installed at different sites, it was possible to fit the analytical method and to compute the characteristic value of micropile resistance. A Monte Carlo analysis has been used to test the reliability of the method and determine the reduction correlation factor for the calculation of the characteristic resistance. The obtained results show how the analytical method can be effectively adopted for micropiles installed in prevalently coarse-grained soils. An appropriate value of the correlation factor that fulfills the reliability requirements has been derived. On the one hand, this correlation factor is only slightly lower than that prescribed by European regulations (Eurocode 7); on the other hand, it appears much less conservative than that prescribed by the Italian Code. The adopted statistical approach appears rather promising to develop appropriate design methods for similar micropile systems in different soils.

This study investigates the efficacy of differing information entropy calculation approaches for concrete structures undergoing alkali-silica reaction (ASR)-induced cracking. In prior work, information entropy has only been utilized for a better understanding of the damage in metallic structures under external loading. To our knowledge, no research has been published regarding information entropy for concrete structures affected by ASR. This scientific gap is addressed in this paper. Furthermore, the innovation lies in using coefficients of determination instead of $b$-values for cracking identification. The entropy results show that the randomness of events increases at the earlier stage of ASR, which is expected due to the microcrack formation, and decreases at the later stage due to the formation of macrocracks. Moreover, a correlation is observed between the coefficients of determination and the evolution of the cumulative signal strength.

This article suggests a new practical method to estimate the nominal shear strength of reinforced concrete (RC) walls. This method identifies whether a specific RC wall is short, slender, or intermediate in height. The aspect ratio (height/length) is a dominant parameter in defining the slenderness of RC walls by many provisions such as the Federal Emergency Management Agency, FEMA 356, in which the aspect ratio of short walls $\le 1.5$, slender walls $\ge 3$, and intermediate walls valued between 1.5 and 3. In this paper, different aspect ratio limits are proposed to determine the slenderness of RC walls, with short walls being $\le 0.5$, slender walls $>1.5$, while intermediate walls are valued in between 0.5 and 1.5. Based on this categorization, the nominal shear strength of short walls is estimated at 75% of the shear capacity calculated based on the American Concrete Institute, ACI 318-14M, for ordinary walls. The shear at nominal flexural strength is considered the nominal shear strength of slender walls. For intermediate walls, a new method is suggested to determine whether shear capacity or shear at nominal flexural strength affects and influences nominal shear strength estimation. To validate this method, the nominal shear strength is estimated as proposed herein for 147 wall specimens experimentally tested by other researchers. The nominal shear strength of these tested walls is calculated based on FEMA 356 provisions and then compared to the results of the proposed method. It is concluded that the proposed method is optimal in estimating the experimental shear strength as compared to FEMA 356.

Water storage and wastewater treatment tanks are usually cylindrical in shape and made of reinforced cement concrete. These tanks are founded at the lowest hydraulic level to facilitate the treatment and storage process. For the designing of such tanks, the governing design forces in the cylindrical wall should be accurately assessed so that the tank satisfies the economic feasibility and serviceability requirements. For transmitting hydrostatic pressure acting on the tank wall into corresponding hoop tension and bending moment, designers make use of design tables offered by the Portland Cement Association (PCA). PCA assumes ideal conditions at wall bottom joints, such as pinned or rigid, but neither considers the effects of annular footing nor soil-structure interaction. At present, there are no design tables available for cylindrical tanks with annular footing. In this paper, using finite element analysis (FEA), the influence of the soil-structure interaction on design forces in the tank wall and the annular footing is discussed. Further, design tables are developed for hoop tension and bending moment for tank wall with annular footing on firm strata.

Structures will eventually develop defects due to aging or overloading, which negatively affect the load-bearing capacity. In certain design details, defects are hidden and difficult to inspect with conventional inspection methods. It is important to introduce damage detection concepts into the earliest stage of structural design. Bolted connections in steel structures form the weakest link due to the risk of stress concentration, stress corrosion cracking, or galvanic corrosion between the connected elements, which cannot be seen visually. In conventional practice, bolts are placed based on the minimum and maximum spacing requirements guided by the American Institute of Steel Construction. In this paper, the periodic placement of bolts instead of irregular distribution was studied as improving the detectability of defects using guided wave ultrasonics. The periodic arrangement of bolts led to a unique frequency response that was utilized in the evaluation of connections based on the hypothesis that the periodic response was influenced by the presence of cracks or section loss. The frequency response curves depending on the bolt layout and topology were obtained numerically. The vibration mode influenced by the presence of defects was identified. The numerical results were validated with the scaled experiments. It was shown that the spatial distribution of bolts assists the damage detection ability, which can be considered as a design criterion of bolt distribution.

A railway bridge over the Paraopeba River was built in Moeda, Minas Gerais, Brazil; however, the railway line for which it was intended was deactivated and, to reuse it as a road bridge, a concrete deck was installed. Upon closer inspection, anomalies were revealed and their causes were found to be related to the installation of the new deck. This work intends to contribute to the structural evaluation and rehabilitation of steel bridges through numerical analysis. For this purpose, a three-dimensional numerical finite-element model of the structure using the SAP2000 version 15 software was developed, in which the acting loads were applied according to the Brazilian standards. The outcomes obtained by the performed nonlinear analysis indicate the occurrence of buckling due to the axial compression load in some structural elements, a phenomenon also observed during the bridge’s first inspection. Thus, to ensure that the bridge is safely reused, the locking of the truss diagonals is proposed as a structural reinforcement. Additionally, the posts’ lateral locking of the three end spans is recommended.

In this study, the economic feasibility of strengthening several types of low-code RC structures in Bucharest is analyzed. Using recently compiled information regarding the characteristics of the residential building stock of Bucharest built in the period 1963–1977, an updated seismic risk assessment is performed. Moreover, analytical fragility functions are obtained for each structural system by employing the same approach that relies on the pushover curve. Subsequently, a logic-tree approach involving previously derived fragility functions is employed for seismic risk computations. Three economic loss models and two casualty loss models were implemented in the risk assessment procedure. The smallest mean annual loss is obtained for the medium-rise large panels structures that had very good behavior during the Vrancea 1977 earthquake. The analysis of the economic feasibility of strengthening shows that the RC soft-story structures appear as the most feasible to be strengthened because the range of costs of the strengthening works is the largest in this case. Correspondingly, the RC dual structures appear as the least feasible for strengthening works among the considered structural systems.