Practice Periodical on Structural Design and Construction

Coupled shear walls (CSWs) are structural systems connect two or more walls at the floor levels by reinforced concrete beams called coupling beams (CBs). These systems have good lateral stiffness and dissipation energy under lateral seismic loading. This paper introduces a comprehensive overview on the seismic behavior and state of the art regarding the conducted research as well as the codes provisions pertained to coupled shear walls systems. Many existing reinforced concrete buildings could suffer from some kinds of failure after strong earthquakes. Consequently, the most efficient and economic retrofitting system has to be figured out and implemented. Therefore, a broad overview on the adopted retrofitting techniques as well as upgrading systems for coupled shear walls is presented and compared. It was found that each retrofitting system came up with some advantages and disadvantages. Thus, the most efficient technique based on the required structural performance level as well as the total cost can be selected.

The case of isolated rectangular footings being subjected to eccentric loads along both directions is very conventional as columns are ordinarily subjected to horizontal loads, vertical loads, and moments simultaneously. Also, its design has not been of much concern for engineers due to the availability of simple mathematical equations for the case when the eccentricity lies within the kern. However, the eccentricity in the case of footings subjected to high biaxial moments normally lies outside the kern area and conventional analysis becomes invalid in those scenarios. Various approximate graphical or analytical methods are available for the analysis in this case. It has been observed that most of these developed models for the biaxial bending scenario are based on the same postulation, and thus it commonly leads to confusion among designers about the most effective and straightforward method to follow during design. Therefore, to avoid the possibility of related confusion and to provide more clarification regarding the existing methods, all the available solutions for the design of the biaxially eccentric condition are critically reviewed in the present study. Moreover, recommendations are proposed for the use of a simple method based on a justifiable comparison highlighting the shortcomings in the applications of other available solutions. Additionally, to enhance the computational efficiency of computer-aided studies and manual assessments, a simplified approach to automate the recommended procedure for the design of rectangular footings is also developed, and correspondingly a pseudoalgorithm is proposed for its easy implementation.

Simple methods are required to reasonably estimate the shear strength of reinforced-concrete haunched beams (RCHBs) for design in order to inhibit shear failures in favor of a flexural behavior. In this paper, design equations developed from stress fields and truss models, also known as strut-and-tie models, are assessed and related with the processed experimental data for the cyclic testing of continuous RCHBs failing in shear. It was found that, for design purposes, plausible estimates for the shear strength of RCHBs could be assessed with the proposed equations.

The inclusion of near-fault effects is now required for building structures designed in accordance with ASCE 7-16 using nonlinear time history analysis. It is also a recognized problem for bridge structures, particularly those with long natural periods. Although existing ground motion databases contain thousands of records, this article shows that just a small percentage contain near-fault pulse-like ground motions. Hence a model for generating synthetic pulses to supplement the available near-fault ground motion data set is necessary and examined in this article. A family of analytic wavelets, known as generalized Morse wavelets, is considered for this purpose. This wavelet family is capable of modeling pulse-like ground motions, using the continuous wavelet transform, by varying two parameters that control wavelet shape and number of oscillations. Using a suite of ground motions that satisfy ASCE 7-16’s near-fault criteria, a model for generating synthetic pulses is created. A series of regression equations for the synthetic pulse model are presented to show the relationship between pulse parameters, peak ground acceleration, and moment magnitude.

A high concrete gravity retaining wall is usually built at the toe of concrete face rockfill dams to accommodate the toe plinth, to avoid adverse natural conditions or excessive excavation. However, earth pressure on the back of the wall is generally neglected due to lack of information on the distribution and evolution of earth pressure during dam construction and reservoir impounding. In this study, two historic cases are reviewed, and a series of plane strain finite element method simulations are performed with an elastoplastic constitutive model for the retained rockfill. The distribution and variation of the normal and shear stresses along the wall–rockfill interface during construction and impounding are studied, and the influence of the interface friction angle is investigated. The evolution of the total normal and shear forces, as well as their application positions, are also analyzed based on the obtained numerical results. Simplifying the dam above the top of the wall as an evenly distributed surface pressure, an empirical formula is proposed to enable evaluation of earth pressure at rest for design purposes. The involved earth pressure coefficient, equivalent dam height, and correcting factor are suggested based on the numerical results. Earth pressures under empty and full reservoir conditions, as well as some favorable design features, are also suggested.

Bridges are the indispensable arterial transport of a country. Iran, as a vast country, needs to develop a variety of road transportation inside and outside cities. Accelerating construction procedures and controlling costs are project management requirements. Risks, in many cases, disrupt the progress of the projects and impose costs on the project. The present article began with field studies, distribution of questionnaires, and the use of SPSS17 software to detect and prioritize the risk of bridge construction projects. Then, dynamic hypotheses were issued for prioritized risks, and causal loops were drawn. Subsequently, another questionnaire was designed to explore the relationship between risks and analyze risk behavior. After obtaining results from field research, the system dynamics and VENSIM7 software were used to model and investigate the behavior and interaction of risks. Finally, ten diagrams showing the effect of risks on each other were exemplified to examine and analyze the designed model.

Currently, castellated and cellular beams (CB) are being increasingly utilized in building construction, but the best design to maximize efficiency is still undecided by most engineers. In addition, the design efficiency characteristics of CBs in common use have not yet been disclosed. Therefore, this study was carried out to expose the efficiency conditions, reveal the states of governing modes in design, and provide design recommendations to obtain the maximum efficiency based on the AISC design guidelines. The results showed that the cost efficiency of fabricating an original steel-wide flange beam to a CB is possibly reduced due to the conservation of the design procedure given by the design guidelines. Overall, a castellated beam can be more efficient than the cellular beam because the applicable limitation of the castellated beam provided in the guidelines is wider than one of the cellular beam. Within the given limits, a cellular beams needs to have an approximate length at least 30 times its gyration radius ($30r_x$) to obtain better efficiency compared to the original beam, while a castellated beam can adaptably be designed to acquire greater efficiency for relatively shorter and longer lengths. The hexagonal openings with wider web post widths, $e$, are needed to resist web post buckling for a relatively short beam length, while narrower web post widths are required to sustain the Vierendeel moment for intermediate beam lengths. The opening cut angle has a slight effect on the overall efficiency compared to other parameters.

The structural design of substructure requires the modulus of a subgrade reaction of the underlying stratum at the soil-structure interface. Its magnitude is estimated by plate load tests at the site. The present study reviewed the magnitudes of the modulus of subgrade reactions obtained from plate load tests, elastic continuum solutions, and a soil-structure interaction analysis of a 2-km tunnel resting on weak sandstones and siltstones. The review showed that the structural adequacy of the substructure using the modulus of subgrade reaction obtained from the Terzaghi equation for plate load tests would not be satisfactory. A modified Terzaghi’s equation is presented so that the magnitude of the modulus of subgrade reaction obtained is of the same order of the magnitude as that obtained from the soil-structure interaction analysis and elastic continuum solutions. The proposed modified Terzaghi’s equation is applied to the plate load test results of two separate projects elsewhere to confirm its validity.

Utilities now have a wider selection of project delivery methods to select from based on their project’s unique characteristics and constraints. The objective of this paper is to study alternative project delivery methods (APDM) implementation practices for water infrastructure projects by assessing the state of practice during procurement and execution. Two of the most commonly used APDM, construction management at risk (CMAR) and design-build (DB), are evaluated alongside the traditional design-bid-build (DBB) method. A survey was developed, based on an extensive literature review and support of an industry expert workshop, and collected information from 75 recently completed water and wastewater treatment plant projects. Key findings revealed in this study specific to APDM water infrastructure delivery include (1) guaranteed maximum price (GMP) is the preferred compensation type; (2) qualifications-based is the preferred procurement method; (3) expedited schedule is the highest selection factor; (4) water stakeholders statistically have the lowest comfort level using CMAR; (5) owner involvement in design is lowest for DB projects; and (6) DBB and APDM have similar procurement durations for water infrastructure projects. This paper contributes to the existing body of knowledge by presenting evidence-based APDM implementation practices that will support utilities with the delivery of their water infrastructure projects.

The compressive strength of masonry is an important consideration in the design of masonry structures. Compressive strength is principally determined in one of two ways specified in The Masonry Society (TMS) 602-16 “Specification for Masonry Structures.” These are respectively the prism test method (PTM), in which masonry prisms are constructed and subject to compression tests as a prediction of the strength of masonry structures, and the unit-strength method (USM), in which concrete masonry unit strength is correlated to mortar strength. Depending on the requirements of the project one method may be preferred over the other. The PTM typically reports greater counmpressive strengths but takes more time and cost for testing compared to the USM, which requires less time and cost but also estimates a lower masonry strength, and therefore recommends a less conservative design. The USM for concrete masonry is based on an existing strength table that correlates the strength of concrete blocks or concrete masonry units (CMUs) and mortar type to masonry strength. However, the USM as currently practiced does not specify block weight or bed joint type (i.e., full bedding or face shell bedding). The present research seeks to determine the best way to apply the USM to lightweight concrete block masonry and to face shell–bedded mortar joints. To investigate the effects of weight and bedding type a total of 48 prisms were constructed; 24 normal-weight and 24 lightweight. For each weight category 12 were fully bedded and 12 were face shell–bedded. All prisms were compared to the USM estimates that are based on TMS 602-16. Results indicate that the USM is not applicable and should not be used for lightweight block or face shell–bedded masonry because it is not sufficiently conservative. Additionally, fully and face shell–bedded prisms were compared and strength ratios were developed.

North American guidelines published by the ASCE and CSA provide a high-level approach for damage classification of blast resistant buildings. Furthermore, the structural damage assessment procedure of critical buildings is overlooked by the petrochemical industry. This paper provides guidelines for the design of buildings subject to far-field blast loads generated within petrochemical plants. A cost-effective procedure for the damage classification of buildings subject to vapor cloud explosions is proposed. The building components are assigned various levels of damage class in order to optimize the material cost. Analytical tools are also proposed that can be utilized by practitioners to assess structural response and select blast loading parameters. Approximate expressions are presented to compute overpressure induced by accidental vapor-cloud blast explosions. The described approach is cost-effective and can be used in the industry to optimize the design of blast-resistant buildings and reduce the project capital cost. Guidelines are provided using a case study for a typical industrial building.

In recent years, through the development of nanoscience and technology, new ideas have emerged for enhancing the performance of cement composites. In this regard, nanomodified mixes, particularly those with nanosilica, have found a special position. However, there are challenges in using nanosilica in cement mixes, such as high price and workability problems. Thus, these materials must be consumed at certain levels to reach goal characteristics. In addition, there are complications in the properties and interactions of materials, which make it difficult to find a simple model for the prediction of concrete properties. In the present study, it has been tried to predict the compressive strength of cement composites utilizing artificial intelligent approaches, including an adaptive neuro-fuzzy inference system (ANFIS), artificial neural network (ANN) technique, and linear and nonlinear regression analyses. ANFIS and ANN are highly reliable methods for predicting the various properties of concrete; thus, these methods have been used extensively in concrete research. However, similar studies were not found on using these methods for prediction of compressive strength of cement mixtures with nanosilica. This study has utilized these methods to provide a comparison between the ANFIS and ANN models in predicting the strength of cementitious mixes and show the capability of the models of ANFIS and ANN compared with the traditional regression methods. For this purpose, the mix proportions and the quantity and size of nanosilica have been considered as input parameters, with the compressive strength of mortars as output parameters. The results indicate that ANN and ANFIS outperformed the regression analyses. Based on the obtained results, ANN had higher accuracy in predicting the compressive strength.

About 9% of bridges in the United States were classified as deficient bridges at the beginning of 2018 with about $123 billion needed for bridge rehabilitation. The bridge decks represent the highest budget associated with bridge maintenance because they deteriorate faster compared with the other components, because of direct exposure to traffic and harsh climate changes. The subjectivity in determining the condition rating is an imprecise process and may significantly affect the maintenance process, which may vary from one inspector to another. Moreover, most research works in prestressed concrete bridges condition ratings have focused predominantly on modeling and have neglected to study the individual effect of geometric variables with excluding the impact of aging and maintenance on the condition rating. The paper’s objectives and proposed contributions are investigating and modeling the impact of explanatory variables on deck condition rating apart from aging and maintenance actions. The findings highlight the design’s contribution to reducing the decline of a bridge condition rating. The stochastic regression analysis has been used to propose a realistic deck condition through a probability distribution. Four models have been developed using the National Bridge Inventory (NBI) of California, and results showed a satisfied coefficient of determination. The developed models have been validated with satisfactory results of 87% using the Average Validity Percentage Method. The developed models will help highway agencies make better decisions regarding future maintenance plans by prioritizing the bridge’s maintenance.

To deal with failure in the closure segment in an existing concrete cable-stayed bridge, a new strengthening method, called the replacement of closure segment (RCS), has emerged in recent years in China. Basically, the construction process of RCS includes removing the failed closure segment, then constructing a new one, and finally improving the connection between the new closure segment and the original and residual part of the main girder by some strengthening measures. To assess the concrete cable-stayed bridge strengthened by RCS, a field loading test was implemented, and several structural indexes were investigated, including deflection of the bridge deck, horizontal displacement of pylons, concrete stress of critical sections in the main girder, and natural vibration characteristics. The results show that the concrete cable-stayed bridge after RCS behaves very well. The measured values of these structural indexes are very consistent with the analytical ones and tend to be safer. Thus, the strength and stiffness of the bridge structure after RCS can satisfy the load-carrying capacity and serviceability requirements specified in its original design. RCS opens up a new way and provides a beneficial exploration for strengthening existing concrete cable-stayed bridges during their use lifetime.

Sustainable concrete construction has encouraged the utilization of industrial wastes [fly ash (FA), silica fume, ground granulated blast furnace slag, metakaolin, and so forth] as a composite cementitious material due to its high pozzolanic activity. Among them, fly-ash concrete is gaining high popularity in the construction industry due to its many benefits to concrete structures, including increased structural performance. To estimate the seismic performance of FA concrete buildings, a probabilistic study was performed to determine its mechanical parameters at various performance limit states. Weibull, normal, log-normal, and gamma distribution probability distribution models were considered for three goodness-of-fit tests: the Kolmogorov–Smirnov (KS), chi-square (CS), and log-likelihood (LK) tests. Among them, the lognormal distribution was found to be the closest distribution describing the variations in the mechanical properties of FA concrete compared with other distributions. It was observed that 20%–40% partial replacement of FA with cement improves the performance of structures with enhanced structural safety at economical cost.

Multistory building construction projects involve time and economy considerations. In this study, an approach to determine a time-optimized solution for speedy construction using a genetic algorithm for a multistory building is used. An objective function is formulated for minimizing the reinforced cement concrete (RCC) work duration, subject to certain constraints, ensuring the practicality and safety of the construction. The solution provides the minimum number of levels of shoring/reshoring that would ensure the least RCC work duration and safe construction. It is found from the study that a total of five levels of shoring/reshoring can ensure safe construction of a multistory building, while keeping the RCC work duration at the minimum, and thus ensure speedy construction. It is also observed that the M45 grade of concrete provides an acceptable shoring/reshoring combination for speedy construction with due consideration of safety. It is recommended that a minimum M30 grade of concrete should be used for speedy construction when the minimum factor of safety requirement is 1.3.

An efficient multiple tuned sloshing damper (MTSD) system is installed in a tall building in Toronto, Canada. The building is monitored before and after water is added to the tanks to measure wind-induced building motion, and evaluate the performance of the MTSD. To the authors’ knowledge, this is the first time an MTSD system has been installed in a tall building, and one of the few times the as-built performance of a tall building supplementary damping system has been evaluated and reported in the literature. Monitoring of the building motion before commissioning the MTSD indicated that the structural frequencies were very close to those originally predicted by the structural engineer’s finite element model. Only 0.8% inherent structural damping was measured for the first mode when the peak building acceleration was 7 milli-g. The measured and wind tunnel predicted wind-induced building accelerations are in good agreement. After commissioning the MTSD system, the measured building accelerations and MTSD wave heights are found to be well-aligned with predictions. Several techniques are used to evaluate the performance of the MTSD system using the measured data. Each technique confirms that the MTSD system reduced building accelerations by approximately 50%. Full-scale structural monitoring has therefore shown that MTSDs can significantly reduce the motion of tall buildings.

The construction industry is known for its conservative approach toward adopting new, emerging technologies. This conservative approach for adopting technology is caused by multiple factors including the lack of adequate resources to guide construction practitioners in the process of evaluating whether a construction firm should adopt a certain technology or not. Previous studies have already proposed rigorous protocols for evaluating work-zone technologies, but the implementation of such protocols is still unclear to many construction practitioners. The objective of this study is to provide a case study example of how evaluation protocols can be used in practice to determine whether a firm should adopt a certain work-zone technology. The case study focused on assessing the usefulness of commercially available work-zone intrusion alert technologies (WZIATs). The results of the evaluation revealed that some WZIATs could be more attractive to construction organizations and agencies in terms of providing louder alarms, being more mobile, and allowing a higher transmission range. The case study example discussed in this study is expected to provide invaluable practical information to practitioners in the construction industry interested in evaluating and adopting emerging technologies.

The construction of a 140-m spanned arch bridge adopted an innovative launching method in which the steel superstructure with a total weight of 2,120 t was entirely assembled and erected on the south side, and then launched northward to span the watercourse. A special hydraulic crawler machinery system was used to drive the launch. Temporary structural and geotechnical facilities, including four launching tracks and their supporting foundations and structures, were designed and implemented. Many investigations were conducted to study the structural and/or geotechnical behaviors related to the launch process and the temporary facilities. In situ geotechnical load tests were carried out for the design of the supporting foundations. The elevations of the superstructure and the temporary facilities were monitored to ensure their vertical alignment. The surface strain in the steel elements of the superstructure and in the launching rails was measured in real time. The results of these investigations are presented, and the lessons learned are discussed.

The bridge spanning Lake Maracaibo in Venezuela, also known as General Rafael Urdaneta Bridge, opened to traffic in 1962 and is frequently referred to as the first modern cable-stayed bridge with multiple spans. The structure extends over 8.7 km (5.4 mi), features six cable-stayed spans, five 235-m-long (771 ft) navigation channels, and was designed by Riccardo Morandi. The remaining spans are formed by a series of piers at variable spacing ranging from 36 to 85 m (118 to 279 ft), which receive simply supported precast prestressed girders. In February 2010, it was found that the support for one prestressed girder had failed and the beam was hanging from the end diaphragm at Pier 27. This paper presents a description of this failure, the replacement of the original supports by pot bearings in combination with flat jacks, and the use of the upper-bound and lower-bound theorems of plasticity to design the retrofitting scheme. The paper also includes a description of the structure and its performance in nearly 60 years of service, the highly corrosive environment of Lake Maracaibo, replacement of the main cable stays in 1980, and a brief comparison with the bridge in Genoa, Italy, that partially collapsed recently, also designed by Morandi.

In this paper, structural adequacy and life-cycle economic feasibility of bamboo as primary construction material for a rooftop low-height telecommunication tower is examined. For this, a relatively strong locally cultivated bamboo species in Bangladesh named Bambusa tulda has been selected for the project. A joint system with transverse steel bolts, with steel plates attached to these bolts, has been proposed as a mechanism to transfer a load between different bamboo members of the tower. Bamboo samples have been tested using this joint system to ascertain the characteristic compressive (40.5 MPa), tensile (53.4 MPa), and bending strength (73.1 MPa) and also the corresponding modulus of elasticity. A 5-m high bamboo lattice tower has been modeled in the three-dimensional finite-element software SAP2000. The analysis results have showed that maximum axial and bending stresses developed in bamboo members of a 5-m high tower is much less than the allowable stresses of bamboo. The top deflection of the bamboo tower has been checked and is found to be within the acceptable limit. An analysis considering a 15-year life-cycle has showed that the bamboo tower is 18% less expensive than a galvanized iron (GI) pipe tower of an equivalent height, which it intends to replace. This proves that a low-height rooftop telecommunication tower may be economically constructed using bamboo.

This article describes the active multichannel analysis of surface waves (MASW) survey conducted at the Jia Bharali River Bed, Tezpur Assam, to identify the shear-wave velocity profile of the subsurface at the site. A new 4-lane (approximately 1.2 km) carriageway bridge construction is proposed over River Jia Bharali, a tributary of River Brahmaputra, intending to connect two national highways NH-52A and NH-37. The site consists of sand and silt deposits, intermingled with pebbles, gravels, and perched hard strata formations. The proposed bridge consists of 24 piers and 2 abutments, each separated by an interval of 48 m. Active MASW surveys were conducted at the pier and abutment locations, along with roll-along mode in-between the piers. Multiple sledgehammer shots were used at each location and dispersion image stacking is used to generate higher resolution dispersion images. Automated extraction of dispersion curve was attained with the aid of image processing techniques employing an integration of Surfseis version 5.0 and Matlab version R2019a software packages. The one-dimensional (1D) shear stiffness profile was determined at each of the test locations, which is further used to decipher the two-dimensional (2D) shear-wave velocity profile along the bridge alignment. The outcome of the analysis could clearly identify the perched hard strata that prevented the progress of borehole driving at specific locations in the site. The bearing stratum could be properly located, which would serve as the foundation depth for the well foundations. The thicknesses of the top erodible sediment deposit, the intermediate soft soil stratum, and the deep-seated bedrock were also effectively recognized. The findings of the survey can aid in effective bridge foundation planning for construction and design.

Moment redistribution due to creep of concrete in cast-in-place segmental cantilever bridges can be accounted for with sophisticated software. Although this approach to design frequently is preferred, experienced engineers often do a final check based on hand calculations that have stood the test of time. This paper deals with the latter approach. Principles governing moment redistribution due to creep were revised, and results from this investigation were used to develop a novel graphical aid suitable for hand calculations in an attempt to estimate the magnitude of tensile stresses due to moment redistribution because of creep. It was found that tension stresses due to creep are not likely to exceed 2 MPa (290 psi) because the post-tensioning provided by top cables balance approximately 70%–85% of the bending moments due to concrete weight. An example for routine designs was provided.

Demand for underground pipelines and the rehabilitation of existing utility infrastructure has been increasing due to urban expansion, continuous development, and the deterioration of existing buried assets. Often, conventional cut and cover (e.g., open-trenching) is the method of choice when rehabilitating or installing new pipelines. However, some underground utilities cross under railroads, and an interruption of railway operations may result in significant economic losses that make it impractical to consider open-trench installation. Moreover, many railway owners will not consider permitting conventional cut and cover utility installations within their rights-of-way. As an alternative, railroad construction guidelines allow the implementation of certain trenchless technologies for new installation and the replacement of the existing pipelines and/or utilities. The purpose of this paper is to provide a general overview of the considerations, typical construction methods, and economic implications concerning railroad underground utility crossings. The paper summarizes the current guidelines provided by the American Railway Engineering and Maintenance-of-Way Association (AREMA) pertaining to a trenchless installation. Additionally, this paper presents a brief case study to introduce an economic analysis for railroad freight transportation and proposes a decision-making model to select the most appropriate trenchless technology method for a specific project.