Practice Periodical on Structural Design and Construction

Seismic base isolation is a passive structural control system that has been effectively utilized as an innovative seismic-resistant design method in the past decades. The properties of earthquake ground motions have significant effects on the response of the base isolation system. Many recent studies were dedicated to the influence of near-fault ground motions on the response of seismically isolated buildings. These previous studies concluded that near-fault ground motions mostly impose larger displacement on the seismic isolators and, in some cases, larger floor acceleration; furthermore, the velocity pulse period influences the seismic isolator displacement and the floor acceleration. Most of the previous studies were conducted using ground motions simulated with certain parametric conditions of near-fault ground motions and/or a limited number of real earthquake ground motions. This study intended to examine the conclusions of previous studies through response history analysis of a seismically isolated prototype building with lead–rubber bearing (LRB) isolators using a large number of real near-fault earthquake ground accelerations. It was found that no consistent resonance phenomenon can be observed when the velocity pulse period is close to the natural period of the isolated building in terms of floor acceleration and isolator displacement, in contrast to the findings of other studies.

Smaller construction firms represent the majority of US construction firms. The safety record of smaller construction firms indicates a lower safety performance and higher incident rates than those found in larger construction firms. Therefore, there is a need for a greater understanding of the challenges that prevent smaller construction firms from achieving higher safety performance levels. Understanding these challenges will help construction safety practitioners and policymakers provide the necessary interventions to improve overall construction site safety. Data were collected from 275 construction practitioners in the US, resulting in scores for safety culture, climate, and behavior. The results suggest a statistically significant positive correlation between firm size and construction safety culture, which represents the safety-related actions of upper management and safety personnel. Thus, interventions that aim to develop sustainable safety and health management systems for smaller construction firms are necessary. On the other hand, the study indicates no statistically significant correlation between firm size and the construction safety climate, which represents the safety-related actions of field personnel (frontline supervisors and workers). These findings contribute to the body of knowledge by providing a meaningful understanding of the interventions needed to improve the overall safety performance of smaller construction firms.

Slab-on-grade construction is popular for heavily loaded ground floor slabs. For design, graphical or tabular methods are recommended by US standards. Scattered design formulations for various loadings, namely, wheel load, distributed load, line load, and concentrated load, are compiled in this article from the literature. The effects of the three pertinent factors, namely, modulus of subgrade reaction, allowable tensile stress in concrete, and load contact area, over the design thickness are examined with a parametric study. The design depth of a slab is more sensitive to the lower values of the modulus of subgrade reaction. The allowable stress in concrete affects the design thickness more for the lower modulus of subgrade reaction, and, therefore, the concrete strength and factor of safety should be carefully chosen in such cases. The contact area of loads (wheel/concentrated) generally do not affect the design depth much, except for a contact area radius that is higher than 75 mm in one formula for concentrated loads. Now, to control cracking due to thermal or shrinkage effects, nominal reinforcement is provided in unreinforced grade slabs according to national (Indian) requirements. Taking advantage of this reinforcement, thickness reduction can facilitate economical construction. A nomogram is available in the literature for that purpose. To avoid human error in the application of the nomogram, a generalized expression was developed in this study. Using this equation, the percentage reduction in the unreinforced thickness of the slab on grade on account of the given percentage reinforcement can be directly estimated, regardless of the system of units followed. Alternatively, the reinforcement provided in existing grade slabs may be used to enhance their load-carrying capacity, and tables and charts showing the (notional) increase in the depth of slabs on grade are provided as well.

A rectangular laminar shear rectangular soil box was designed and fabricated that consisted of multilayer steel frames to minimize the influence of the boundary effect of soil boxes used for the soil–structure shaking-table tests. Omnidirectional rolling bearings were placed between the vertical adjacent frames of the soil box, allowing the frame to rotate in any direction out of plane. The dynamic characteristics of the laminar shear soil box are analyzed based on computer modeling and the shaking table’s movement. Results showed that the natural frequency and damping ratio of the laminar shear soil box were considerably different from those of the soil sample. The acceleration of time history and the frequency spectrum of each measuring point at the same depth of the soil sample were highly consistent, and the boundary effect index associated with each measuring point was low. The influence of the boundary effect can be effectively eliminated using the laminar shear soil box; therefore, it can be used in the soil–structure shaking-table tests.

In-plane behavior of timber diaphragms is usually characterized by means of an equivalent shear stiffness. However, this value depends on how the stiffness of the floors is evaluated from the experimental tests. Although an increasing number of research studies have provided a deeper insight into the seismic characterization of as-built and retrofitted timber diaphragms, the use of different standards or assumptions have led to inhomogeneous and not comparable results. With a focus on light, reversible, wood-based strengthening techniques applied to existing diaphragms, this study proposes a uniform and simple method based on the calculation of the secant stiffness of the floors at reference drifts. By means of this procedure, relevant research studies from the literature were compared, and homogeneous, indicative values of equivalent shear stiffness were proposed for each considered strengthening technique. These results can contribute to a more aware and reliable use, design, and linear modeling of wood-based retrofitting solutions for existing timber diaphragms.

Diagrid structures recently have evolved as novel solutions for the design of tall buildings with unique geometrical layouts. The aesthetic value and flexibility in accommodating distinctive geometrical constraints make diagrids an attractive solution for many innovative structural designs. In diagrid structural systems, most often the diagonal bracings act as both primary gravity load resisting and lateral load–resisting elements. Another defining feature associated with this system is its reduced ductility, especially for shear-dominant systems with lower diagonal angles. Typically characterized by less structural redundancy and a nonductile postyield response, the design of diagrid structures in high seismic zones should be treated with caution. There could be a false sense that a structural system which is proven to be efficient for high-rise buildings could safely satisfy the requirements for low- to midrise structures. The increasing demand for free-form geometrical layouts could result in instinctive and incautious selection of these structural systems for low- to midrise buildings because of their effectiveness in high rise structures. However, under high levels of axial compression (typically associated with high seismicity), the diagonal members could be subjected to buckling, and the limited redundancy in the structural configuration significantly could affect the global postyield response of the structural system. Hence, this paper examined a case in which a diagrid structural system was used for the concept design of a multistory commercial structure in a high seismic zone, and the inefficacy associated with the seismic behavior of the system was addressed successfully by adopting two different methodologies, with buckling-resistant braces (BRBs) as the diagonal elements in the first approach and yielding connectors (YCs) as fuse elements in the second approach. Both solutions performed well in terms of improving the postyield response of the system. However, the use of yield connectors could be particularly effective in shear-dominant diagrid systems with lower diagonal angles due to the postyield hardening response in compression demonstrated by the connector elements.

Beam-column (BC) joints play an important role in the seismic performance of moment-resisting RC frame structures. Several techniques have been suggested to improve the seismic efficiency of BC joints, but these techniques have been criticized for being labor-intensive and/or vulnerable to premature debonding. To overcome these deficiencies, a novel stochastic lattice structure is proposed in this work to improve the shear-deficient RC BC joints. The optimization procedure was carried out for different shapes of stochastic lattice structures that give the maximum shear capacity, and the shear capacity is compared with the designed exterior standard beam-column joint. The expression for shear capacity of the stochastic lattice structure was formulated by considering a unit cell of 10 mm length. The maximum shear capacities of the triangle, hexagon, and pentagon shapes were obtained by varying the cell angle and length. The results of different cell shapes were compared with the allowable shear stress of designed beam-column joints. In addition to the optimization procedure, three-dimensional (3D) finite-element (FE) models were developed to study the behavior of the joints using the optimized stochastic lattice in the joint core. Compared with the control specimen, the beam-column joints with the proposed lattice give much better performance in terms of cumulative energy dissipation, lateral stiffness, joint shear deformation, and angle of beam rotation.

Shear walls are lateral load–resisting systems that provide lateral strength and stiffness in order to reduce the horizontal sway of a building. Over recent years, composite shear walls with steel-encased profiles (CSRCWs) have attracted increasing attention. This paper aims to numerically investigate the impact of axial loads on the seismic behavior of shear walls. Numerical modeling was carried out via OpenSees. Five composite shear walls with different shapes of steel-encased profile and one typical reinforced concrete (RC) shear wall subjected to lateral cyclic displacements and different levels of axial load in the range of 10%–40% of axial load capacity were investigated. The findings revealed that increasing the axial compressive load ratio has a negative effect on the seismic behavior of shear walls. In addition, the results showed that shear walls with steel-encased profiles have more flexibility, stiffness, and energy dissipation compared with typical RC shear walls under the same axial load.

Project control operations in construction are mostly executed via direct observations and the manual monitoring of progress and performance of construction tasks on the job site. Project engineers move physically within job-site areas to ensure activities are executed as planned. Such physical displacements are error-prone and ineffective in cost and time, particularly in larger construction zones. It is critical to explore new methods and technologies to effectively assist performance control operations by rapidly capturing data from materials and equipment on the job site. Motivated by the ubiquitous use of unmanned aerial vehicles (UAVs) in construction projects and the maturity of computer-vision-based machine-learning (ML) techniques, this research investigates the challenges of object detection—the process of predicting classes of objects (specified construction materials and equipment)—in real time. The study addresses the challenges of data collection and predictions for remote monitoring in project control activities. It uses these two proven and robust technologies by exploring factors that impact the use of UAV aerial images to design and implement object detectors through an analytical conceptualization and a showcase demonstration. The approach sheds light on the applications of deep-learning techniques to access and rapidly identify and classify resources in real-time. It paves the way to shift from costly and time-consuming job-site walkthroughs that are coupled with manual data processing and input to more automated, streamlined operations. The research found that the critical factor to develop object detectors with acceptable levels of accuracy is collecting aerial images with for adequate scales with high frequencies from different positions of the same construction areas.

Concrete highway bridge remaining service life has been at the forefront of bridge owners’ concerns for several years in terms of growing bridge maintenance needs. Distresses in concrete bridge components occur due to physical, chemical, and mechanical factors that manifest as observable symptoms of deterioration. Deterioration models realistically link the observable defects to the several explanatory variables affecting the deterioration that aid in the planning of appropriate corrective actions. Only a limited number of explanatory variables have been considered in the published literature in the development of bridge component deterioration models. This study investigates the effect of multiple relevant explanatory variables affecting the bridge component condition including aging, loads and environmental conditions, and design characteristics using a multivariate regression analysis approach. Deterioration models for both superstructure and substructure of reinforced and prestressed concrete bridges are developed and validated in the present study. The proposed models will aid the bridge engineers to predict the concrete bridge component conditions based on bridge characteristics for planning preventive maintenance.

Time-dependent settlements of piled raft foundations embedded in consolidating clays were studied using three-dimensional (3D) finite-element analysis and critical state-based soil constitutive modified Cam-Clay (MCC) model. In this study, different small to large rectangular rafts connected to circular bored cast-in-situ piles resting on four different types of clays and with varying overconsolidation ratios (OCRs) (1, 2, and 5) for each clay under a single drainage condition were analyzed. The influence of various piled raft parameters (pile length, pile spacing, pile diameter, raft thickness) and soil parameters (Poisson’s ratio of soil, soil critical state parameters, stress history of soil or OCR) on immediate and consolidation settlements of piled rafts were investigated. The detailed parametric study shows that critical state parameters and soil elastic properties have important roles in piled raft immediate and consolidation settlements. However, the pattern of parametric influence on immediate settlement and consolidation settlement is different. To capture the total settlement at the end of primary consolidation, a simple and quick calculation method for estimating the average soil subgrade modulus below the piled raft in consolidating clays is proposed through regression analysis and defining a combined influence parameter based on soil parameters, area ratio, and normalized loading. The results of the proposed method were compared with five case studies of piled raft foundations in various normally or overconsolidated clays showing satisfactory matches. It is believed that the proposed method will be very useful for design practitioners to get a quick estimate for the overall settlement of piled raft at the initial design stage.

In reinforced concrete (RC) moment frames, the performance of the whole structure to provide a suitable strength against lateral loads depends on the behavior of each structural element. Therefore, the capacity of such members plays a vital role in the final response of RC buildings. However, the nonlinear nature of complex materials like concrete and its combination with other parameters makes the calculation of capacity more difficult. An estimation of the strength is a critical challenge in civil engineering with many applications, especially for damage detection, retrofitting, and strengthening programs. In this article, new computational frameworks are evaluated to introduce innovative approaches with the aim of determining the structural capacity of beams, columns, and joints in RC frames using soft computing (SC) techniques. Neuro-fuzzy models, group method of data handling (GMDH), and, also, three different structures of neural networks are presented and discussed. To this end, three collections of experimental datasets are gathered to assess the models. Moreover, mathematical equations are extracted from the considered systems for practical usages. Finally, the best predictive model for each structural element is proposed in detail. A comparison study between the results obtained from the presented methods and the laboratory values indicates that the proposed models can estimate the capacity of the elements with high accuracy and can be used as a powerful tool for evaluating the capacity of the structural members of RC frames.

A damage index study is necessary for evaluating the post-earthquake health of structures, and it is also required in performance based seismic design (PBSD), where engineers can design a structure for desired predefined target performance objectives. The existing damage assessment methods give different magnitudes of story damage index (SDI) or global damage index (GDI) for a given building under the same hazard level. These existing methods also give different SDI patterns. Therefore, it is difficult to identify the appropriate method to estimate the damage index (DI) for a structure. In this paper, 14 different existing damage assessment methods were studied to investigate their characteristics and reliability. The aim of this study is to determine appropriate and reliable damage assessment methods amongst the available existing methods, and to propose a new multivariate damage assessment model combining those reliable damage assessment methods. Based on the statistical hypothesis T-test conducted for 14 existing model equations, three methods are found to be most reliable and effective to assess the DI of buildings, meeting a 95% confidence level. Combining these three models, a new multivariate damage assessment model is proposed that shows a good agreement with those models, having ${\mathrm{R}}^2=0.91$. This study resolves the ambiguity in selection of the most reliable methods among the existing models.

The manufacture of electronic devices produces a lot of plastics wastes, mainly PVC. This type of waste is usually burned, producing harmful gases during incineration; therefore, recycling PVC waste is becoming a global concern. The prospective of using electric PVC wires in concrete and the influence of PVC waste on the flexural behavior of the RC beams are studied in this research. The compressive and tensile behaviors of concrete made with PVC wires and steel fibers are also investigated. Eight RC beams were tested under four-point loading test. Different percentages of PVC wires and steel fibers were included separately in concrete: 5%, 10%, and 15% of the total cement weight. Test results showed that for flexural strengthening of RC beams made with plastic wires, the ductility factor of the RC beams was significantly increased up to 3.5 times that measured in the control specimen, where the maximum enhancement was measured with 15% PVC wires. The deflection and the flexural strength were also increased when using PVC wires. PVC wires are superior to steel fibers in increasing the ductility of RC beams. Finite-element models were also developed using Abaqus and they were able to predict the experimental behavior. Test results confirmed the possibility of using PVC wires in concrete, while they showed that PVC can significantly increase the ductility of RC beams.

Structural design of high-rise buildings usually poses a great challenge to structural engineers, especially if those buildings have complicated architectural configurations. The difficulty to model numerically with high precision the different structural elements for these complicated buildings during the design process can result in improper estimation of the straining actions within these elements. Structural health monitoring (SHM) provides a proper tool to ensure the accuracy of these numerical models, in addition to evaluating the structural integrity and safety of structures during and after construction. This paper presents an efficient strategy that was utilized for monitoring the stresses within the critical structural elements of Makkah Clock Tower at Kingdom of Saudi Arabia (KSA), which is the third tallest building in the world. The aims of this strategy were to validate the building analytical design models, verify the design assumptions, and evaluate the building structural integrity and safety during and after construction. This strategy was based on placing vibrating wire strain gauges within the building’s critical structural elements to measure the strains, which can be later converted into stresses exerted on these elements in order to verify the results obtained from the building finite-element design model and to ensure that these stresses are within code limits. The results showed that this strategy provided an effective mean for validating the accuracy of the structural design model and ensuring the structural safety of the building.

This paper presents new formulae for the determination of the plastic strengths of steel I-sections subjected to uniaxial bending about major or minor axis combined with an axial compression force. Moreover, new formulae are developed to describe the plastic yield surfaces of steel I-sections under biaxial bending moments combined with an axial force. The proposed formulae are obtained by performing large data regression analysis on the exact I-section strength results. In addition, the proposed formulae are simple and valid for any standard or general steel I-section, with conditions dependent on dimension ratios. These formulae are compared with the exact analytical solutions and with previous analysis methods and show very good correlations. New modified simple formulae are derived to predict the yield surface of I-sections. These formulae are more practical and easier for design purposes and lead to very good results compared to existing standards and exact solutions.

The purpose of this paper is to present an innovative equation to predict the moment capacity of spirally reinforced concrete columns with high accuracy using a combination of neural network and metaheuristic optimization algorithms. To this end, a large experimental database has been gathered to train a neural network with seven independent parameters that deal with the dimensional properties of the columns, reinforcements, materials, and also the forces. Furthermore, the authors improved the process of training with consideration of two optimization techniques: particle swarm optimization (PSO) and Harris hawks optimization (HHO). Then, the best model was selected to a statistical methodology to extract an empirical equation to predict the target, which makes the proposed system of this article more applicable, especially for the practical usages. The results indicated that the neural network with the PSO algorithm had better results than the other model. Also, it has been found that the proposed formulation could predict the moment capacity of the considered element with high performance. The presented equation of this article has many applications in civil engineering, such as retrofitting and rehabilitation.

This paper presents a retrofitting method for older-design eccentrically braced frame. Numerical experimentation was carried out for the old designed eccentrically braced frame and the modified versions of that the frame. Compared with a well-designed eccentrically braced frame designed using current seismic provisions, the behavior of the old designed eccentrically braced frame was not desirable. The contribution of the link in plastic dissipation was minimal even after following the criteria of shear link. Plastic dissipation by the frame, the braces, and the beam outside link was undesirably significant. The hysteresis loop was unstable, and significant strength degradation was observed. The structural behavior was improved by introducing the retrofitting measures in such a way that the structural interventions and the disruption to the occupants would be minimal. After modification, the maximum plastic dissipation was contributed by the link portion, as desired. The hysteretic behavior and the plastic dissipation were improved significantly, and the strength degradation was minimized.

This paper presents a formula for evaluating the temperature distribution in RC circular columns exposed to standard fire scenarios. Unlike the detailed solution to the heat transfer differential equation, the proposed model is simple to use. Application of the proposed formula does not require numerical analysis, and it can be applied to generate, with sufficient accuracy, temperature distributions within a cross section at any specified time and location. Derivation of the formula was based on a regression analysis of a large set of results generated by finite difference calculations. The regression formulas yielded a root-mean-square error of 21.7°C, where most errors within the practical temperature range of 200°C–800°C do not exceed $\pm 15\%$ (compared with the numerical results). The proposed model was verified against the results of the finite difference calculations and validated against published experimental results. It can provide predictions for both normal- and high-strength concrete, with different aggregate types and different moisture contents. The simplification and the wide applicability of the proposed model make it worthwhile and useful for structural fire design, as illustrated by the examples given at the end of the paper.

The reflections of waves collide with the slope, and the reduction in the ground lateral stiffness in the areas near the slope crest affects buildings. In this research, using the three-dimensional simulation, the seismic response of midrise reinforced concrete buildings located in the vicinity of slopes was investigated. The nonlinear soil behavior was simulated using an isotropic hardening elastoplastic hysteretic constitutive model, i.e., the hardening soil model with small-strain stiffness (HSS). The inelastic behavior for building components was considered using elastoplastic hinges. Results were presented as a ratio of topography–soil–structure interaction (TSSI) responses to soil–structure interaction (SSI) responses. The results showed that the topography of the slope increases the natural period range in the vicinity of the slope compared with cases without slopes. The maximum lateral displacement of the building and its maximum base shear force were 40% and 12% higher, respectively, in the TSSI mode than in the SSI mode.

Fatigue damage is treacherous and can lead to the failure of offshore structures. The purpose of this research is to evaluate and discuss the stress concentration factor (SCF) values for two geometries of offshore tubular KT joints using different calculation methods to be used in fatigue design. The work was done by using analytical calculations, formulations from the literature, and numerical solutions, finite-element method (FEM) analysis using commerically available software, supported by international standard recommendations. For the analytical formulations, geometrical parameters were used as defined in standard recommendations. For the numerical model, two different geometries of tubular KT joints are presented where different shell (S4R), solid (C3D8R), and solid with weld (C3D8R) element-type models were built in the software environment. After considering 23 different types of loading conditions, a comparison between the standard SCF and finite-element analysis (FEA) SCF values for the critical load case has been performed. The results have shown that the values of SCF from the standard are more conservative than SCF from FEA. However, FEA SCF values for the solid and solid with weld element types have shown little differences.

In precast grid systems, it is necessary to support the cross beams by the main girders using suitable methods. One of these proposals is by making voids or notches within the webs of the girder to include the supports of the cross beams. In this paper, an experimental study has been done on 10 reinforced concrete self-consolidating beams with loaded openings. The tested specimens have been categorized into two groups based on one inclusion of dapped ends. Each group consists of five specimens; one served as a control in which the opening is reinforced conventionally with two vertical stirrups at both sides. For the other specimens, the openings are reinforced with different schemes, namely using steel-fiber concrete, diagonal bars, jacketing by steel plates, and a composite section for the bottom chord. The behavior has been discussed in terms of history of crack propagation, loading history, ductility, and toughness. It was concluded that inclusion of the dapped ends reduced the capacity in range of 9%–12%. Moreover, results revealed that the composite section proposal yielded the highest enhancements of 21% and 23% for the two groups, respectively. Regarding ductility, maximum enhancements of 44% and 9% were noticed. For the toughness, the proposal of a composite section yielded the highest improvements by 91% and 19%, respectively.

The performance of cross-laminated timber (CLT) panels in building applications have been investigated extensively. However, limited information is available regarding the performance of CLT panels for bridge applications, as well as the torsional performance of CLT panels under asymmetric loading, geometry, and boundary conditions. The objective of this study was to investigate the torsional performance of skewed CLT pedestrian interior bridge deck panels through large-scale structural testing. The panels were designed as a pedestrian bridge crossing over an atrium of The Canyons building in Portland, OR. The test panels were subjected to line and uniformly distributed loads to replicate the reactions from the adjacent panels and design loads directly applied to the panel, respectively. Two different loading configurations based on the 2014 Oregon Structural Specialty Code (OSSC) were applied with up to three different loading intensity levels. An additional loading configuration, which was beyond the scope of the OSSC, was also applied in the second series of tests to determine if panel failure could be induced. The test results demonstrated that the test panels were able to recover their original shape without suffering major damages on the panel. The measured residual deformation after the removal of the applied load was very small. The findings of this study broaden the current state of knowledge of the structural performance of a CLT bridge deck panel under asymmetric loading, and the test results can be used for future design problems.

Civil engineers have struggled to prepare budget estimates for transit terminal projects that include recent advances in safety and risk analysis during construction. They question whether their standard cost estimates are suitable for an expansion project that by necessity imposes severe restrictions. Safe transit projects are crucial in the development and growth of economies. Safe work zones require proper illumination to insure good visibility of workers and their equipment. Identifying and understanding the factors that influence the cost of a transit expansion project is of great importance throughout its development. This case study builds on studies of many projects of varied scope. The variables are many, and often the constraints do not match the activity under consideration. This model’s structure and principles are targeted at the expansion of an existing transit hub that is active and necessary for the economic health of a community. The model that has been developed in this case study provides an overview of the project’s anticipated costs. The objective of the case study is to present a model that may be utilized to prepare a budget estimate for the expansion of an active bus and rail terminal that will grow through periodic updates to produce a final cost. The objective of this research is to review the risk of different variables that are predictive of superior safety performance and present a revised framework that satisfies the needs of owners to measure the culture of safety and risk using a practical model.

Transportation agencies have been facing the challenge of shrinking budgets and reductions in the size of inspection staff with an increased number of construction projects over the last decade. For portland cement concrete pavement (PCCP) projects, a large number of quality assurance (QA) tests are typically conducted to ensure the quality of roadway construction is met. Yet, relatively little research has focused on identifying and prioritizing PCCP tests that matter in terms of design service life performance. To address this gap, a risk-based framework was developed. A core list of 10 PCCP material tests was identified through a comprehensive literature review and survey. These tests were then evaluated to determine the risk levels and sampling frequencies. The risk level was determined using a four-point scale of both probabilities (high, moderate, low, and rare) and consequences (critical, major, minor, and contractual). Based on the risk rating system, four tiers of material tests were proposed. A case study example was presented to illustrate and validate the framework. The result showed that there is one QA test in Tier 1, three QA tests in Tier 2, five QA tests in Tier 3, and one QA test in Tier 4. The finding of this study showed that QA tests with high-risk levels require more sampling and testing frequency than those with lower risk levels. This study adds value to the body of knowledge by providing risk-based guidance on evaluating and determining QA test frequencies for PCCP. This study also helps transportation agencies prioritize QA tests and optimize sampling and testing of PCCP construction projects.

This study proposes a practical solution for installing anchoring elements on hard or old concrete surfaces to receive tensile forces. For this situation, where the anchorages will be postinstalled, there is often no depth in the concrete base that meets the minimum straight length of standard anchoring. Thus, the use of headed studs or hooked anchor bolts are the most recommended solutions, but the procedure for installing these elements is still the subject of experimental investigations. Then, the technique of postinstallation of headed studs in hardened concrete niches and the use of structural epoxy resin in the new-old concrete interface is presented. Additionally, the influence of the addition of steel fiber on the anchorage studs performance was also evaluated.

Reinforced concrete slabs are often exposed to rain and radiation from the sun, in addition to normal loads, and hence have to be provided with at least the minimum shrinkage and temperature reinforcement. Shrinkage and temperature reinforcement has traditionally been specified as a certain percentage of the cross-sectional area (about 0.12%–0.18%), which is often empirical. Moreover, this was specified when M20–M25 concrete and reinforcements of Grade Fe 415 were used, which have since been found to be inadequate by practicing engineers. Some researchers have found that the reinforcement prescribed in codes has to be increased considerably to avoid cracks due to shrinkage and temperature effects. Hence, a formula for minimum reinforcement has been developed for slabs, similar to that for beams, which provides consistent safety against collapse due to cracking. It takes into account factors that may affect the behavior of these slabs, such as concrete and steel strength and the ratio of depth to effective depth.