Practice Periodical on Structural Design and Construction

The present paper suggests an efficient preconditioned two-iteration substructure approach—namely, preconditioned soil–structure interaction (PSSI)—to couple the analysis of a superstructure over fixed bases (which is traditionally carried out in design companies) with the analysis of foundation plates over an elastic half-space (EHS) to obtain more accurate equivalent supporting spring stiffnesses. Hence, an accurate building time period and, consequently, lateral loads could be computed. The effectiveness of the proposed approach is illustrated in several numerical examples in terms of number of iterations and scalability followed by comparison with previous work to demonstrate the superiority of the proposed approach.

A cross-drain structure provides an opening under a highway. Cross drains must be provided transversely under highway embankments to cross obstructions such as canals, streams, and natural depressions. A cross drain is categorized according to its shape, such as an arch, slab, or box. The size of the cross drain is based on the width and depth of the obstruction. The maximum width of the cross drain is restricted to 6 m by the Indian Road Congress (IRC) standard. The National Highway Authority of India (NHAI) has set a target of constructing 39 km of roads per day. An average of two to three cross drains are required per kilometer length of highway, depending upon the topography. Thus, per day, 78 to 117 cross drains must be designed and constructed. To achieve this target, cross-drain sections should be standardized. This paper deals with cross-drain design in reinforced cement concrete (RCC) with a constant clear width of 1.5 m and a cushion of 0 to 6 m of soil over the cross drain. The vertical opening and invert levels (ILs) are decided according to hydraulic requirements, existing ground levels (EGLs), road profile, and site constraints. The cushion variable depends on the highway profile and the EGL at the cross-drain location. This paper focuses on the analysis and structural design of box-type cross drains. We used the STAAD_PRO (version 8i) program was for analysis, and we used AUTO-CAD 2016 for the preparation of drawings and figures. We analyzed the box-type cross drain for all possible load combinations mentioned in the IRC code. We considered the maximum bending moment, shear force, and crack width criteria to design the structural elements. The graphical representation of the size and shape of structural elements for various parameters is a major outcome of the study. We summarized the required bearing capacity is in tabular format. The adoption of these standard figures will aid the design of cross drains more quickly and with reduced effort.

Tensile membrane structures (TMS) are increasingly in demand due to their ability to span large distances with elegance and structural efficiency. Because TMS is comparatively new to the structural engineering world, there are relatively limited resources available explaining the behavior of such structures. Most countries do not have documented guidelines for the analysis and design of TMS. This paper presents the existing challenges and provides some recommendations on the analysis and design of membrane structures. Emphasis is placed on form-finding, which is the initial equilibrium analysis of membranes. Attention is also given to understanding the behavior of TMS subjected to environmental forces, especially because of their inherent flexibility that imparts a complex interaction between the form and the applied forces.

Most bridge design standards do not consider a dynamic analysis but instead consider an equivalent static analysis. In addition, the few engineers who carry out dynamic analysis do not usually consider the interaction between the bridge and vehicles. Thus, in this article, a simple methodology to consider the interaction between the bridge and vehicles in the dynamic analysis of bridges is proposed. The proposed method allows determining the dynamic response of road bridges due to the dynamic loads caused by vehicles traveling on rough pavement, taking into account the bridge–vehicle interaction. For illustration purposes, the proposed methodology is applied to a concrete bridge built on the Rio-Santos highway (Rio de Janeiro, Brazil). The bridge was modeled as a simply supported highway box girder bridge without balances divided into beam elements according to the FEM, the pavement-roughness profiles were obtained according to the ISO 8608 standard, four simplified models of vehicles were used, and the dynamic analysis was performed through the Newmark method. The results show that the proposed method is able to determine the dynamic response of the bridge, taking into account the bridge–vehicle interaction. Therefore, the proposed methodology can be recommended as an effective tool to improve bridge design.

General purpose finite-element software tools have put nonlinear analysis within an engineer’s reach for the assessment of bridge response to seismic loading. Although these tools can capture strength, ductility, and nonlinear material and geometric effects more accurately than response spectrum or linear methods, the response is extremely sensitive to modeling techniques, even when the same input parameters for bridge geometry and material properties are used in different software packages. The resulting discrepancies in nonlinear response are due to mathematical formulations of the element response, for example, concentrated or distributed plasticity, and software-dependent implementation of the formulations and their constitutive models. To illustrate the effects of modeling choices and the ability of two widely used software packages, CSiBridge and OpenSees, to reproduce analytical solutions, concentrated and distributed plasticity models were applied to cantilever bridge columns with simplified steel and concrete constitutive models. Discrepancies in stiffness and strength owing to the location and length of plastic hinges can be resolved for these simple component models. The modeling strategies were extended to two ordinary standard bridges designed by Caltrans. Although modal analyses show the bridge models have approximately the same distribution of mass and stiffness in the two software packages, only nominally consistent results can be achieved when using more realistic constitutive models for nonlinear static analyses.

A full-scale static test to failure was conducted on 6-m (236.22 in.)-long steel pipes constituting a segment of a telescopic wind tower with a 60-kW wind turbine. The diameter of the circular cross section of the steel pipes was 900 mm (35.43 in.), and the nominal thickness was 10 mm (0.39 in.). The steel grade was 355 MPa (51,488 psi). The tests were conducted in a force-controlled mode in a four-point bending test with a shear-to-span ratio of 2.05. The flexural limit states developed in the form of ovalization of the cross section and of local buckling. The buckling occurred in the plastic range because of the diameter-to-thickness ratio of the section. Although local buckling caused slight strength degradation, the reduction due to the shear-to-moment interaction and ovalization of the cross section was very significant (58%), while the recorded response revealed a good amount of postbuckling ductility (2.42). A finite-element analysis with ABAQUS code was also conducted for comparison with the experimental results and for validation of the simplified proposed model. By properly modeling the imperfection effects due to the roundness of the steel tube, good correlation of the structural response and failure mode, and with the analytical model, were also achieved.

Construction delays are a common problem in all developing and developed countries, costing the industry billions of dollars every year. Understanding the major delay factors for construction projects is the first step in reducing this unnecessary loss. There are 6, 15, 3, and 5 studies identifying the respective top delay factors of Indonesia, Malaysia, Vietnam, and Thailand reported in the literature. Thirty-five of 42 possible delay factors were identified as top delay factors for these countries, which means that some factors may not be appropriate. An examination of these 29 studies is required to establish the respective top delay factors of Indonesia, Malaysia, Thailand, and Vietnam. Preventive/mitigating measures for each top delay factor identified to minimize construction delays in Indonesia, Malaysia, Thailand, and Vietnam are presented.

This experimental study attempts to investigate the flexural behavior of continuous reinforced concrete (RC) beams strengthened by near-surface-mounted steel bars. The tests were conducted on 11 3,000-mm specimens with cross-sectional dimensions of 150 × 225 mm. The longitudinal reinforcement of all beams consisted of two ϕ10 steel bars in the negative and positive moment regions. To ensure that the beams would fail under flexure rather than shear, ϕ10 stirrups were spaced at 100 mm c/c over the entire beam length. The first beam was not strengthened and was considered a control beam. The other specimens were strengthened by near-surface-mounted bars with different development lengths, diameters, and material types, with end-anchors of carbon-fiber-reinforced polymer (CFRP) fabrics. The test was conducted under two-point loads, applied at the center (1,400 mm) of the span. The main investigated characteristics were cracking and ultimate loads, crack width, displacement, and failure modes. From the experiments, all the strengthened beams achieved a significant enhancement in ultimate flexural strength by approximately 108% relative to the control beam. In addition, CFRP end-anchorage can eliminate the separation of the concrete cover and demonstrates a significant improvement in ductility.

This research mainly focused on energy simulation for residential buildings with different types of wall systems in Boston. Building-envelope systems have a significant influence on the whole building’s energy performance, and therefore quantitative comparisons are of interest. In this study, several types of high-performance wall systems, including advanced framing, structural insulated panels, insulated concrete forms, and the exterior insulation and finish system, as well as the most common wood-stud wall system, were studied with the use of building energy simulation. The results show that all of these types of wall systems effectively reduce the annual energy consumption, and the insulated concrete form is the best-performing method and has annual energy savings of 8.94% compared with the standard 50.8 × 101.6 mm (2 × 4 in.) wood-frame wall in Boston. The results also validate the anti-insulation effect at Philadelphia and Syracuse, which means that in some cases, increasing the insulation beyond a certain level may actually increase the use of energy for cooling. A life-cycle assessment was also performed, and the results show that the insulated concrete form wall system with a 152.4-mm (6-in.) concrete core has the best long-term energy performance, with overall life-cycle savings of 8%.

This article presents a concise overview on condition monitoring and retrofitting/strengthening of structures, including a practical case study of strengthening for an existing historical building. Condition assessment of an existing structure is required mainly to check serviceability and safety requirements of the structure after short-term events, such as earthquakes or long-term degradation of the structure with time. It is carried out to assess the ability of a structure to perform its intended operations under changed loading conditions with time or modification in its structural system as per newly imposed requirements. The condition assessment and strengthening may also be required for the integrated extension of an existing structure. After assessing the condition of the structure, either it is retrofitted (or strengthened) or it is demolished according to the severity of the damage. In this article, such a critical condition assessment for an existing historical masonry building is presented, and appropriate strengthening schemes are suggested by following two separate measures (concrete jacketing and fiber-reinforced polymer strengthening). Subsequently, the relative advantages and disadvantages of the strengthening measures are discussed from a practical engineering perspective. The aim of this article is not to propose any new method for condition assessment and strengthening of structures; rather, we take a systematic approach to demonstrate our experience. Critical case studies on condition assessment and strengthening of historical buildings with adequate technical insights are very scarce in scientific literature. This article would serve as a valuable reference for practicing engineers and the concerned scientific community.

It is inevitable that the components of highway bridges will develop flaws due to mechanical and environmental loads. Bridges are typically inspected visually to determine their condition and serviceability. Unfortunately, current design practice often does not explicitly consider inspectability and the means of structural damage detection in the design process. It is important to integrate damage monitoring and inspection strategies into the earliest stages of the design of highway bridges for resilient structural behavior. This technical note summarizes the outcomes of the workshop organized at the University of Illinois at Chicago on structural design and inspectability of highway bridges. The workshop brought public agencies; design, construction and inspection companies; and academicians together to discuss the challenges of current practice for inspection and concepts to be implemented in the next generation highway bridge design for better inspectability and maintenance.