Innovative Infrastructure Solutions

A series of reduced-scale models were tested to assess the performance of non-yielding basement wall due to strip footing constructed adjacent to it. Construction design parameters such as strip footing width (B), its distance from non-yielding wall back (a), and footing embedment depth below the backfill surface (df) have been considered in this study. This paper presents results of five model tests that isolate effects of non-yielding wall on the strip ultimate footing bearing capacity. The opposite effect of the strip footing distance design parameters on the non-yielding wall responses is also investigated. Experimental results revealed that the strip footing load-carrying capacity increased, and the settlement decreased as its distance from the back of non-yielding wall increased. Furthermore, the vertically loaded strip footing imposed significant vertical and horizontal forces at the back of the non-yielding wall. Results also indicate that distance a > 4B between the footing and the back of the wall enabled the strip footing to mobilize ultimate load-carrying capacity comparable to both control strip footing test and value calculated with Terzaghi’s equation. Comparison of the measured and predicted lateral forces showed that using elastic theory method together with Jacky formula for at-rest lateral earth pressure coefficient led to about 23–35% underestimation of the measured lateral forces. However, including sand overconsolidation ratio, OCR = 2 resulted in an overestimation of the lateral forces by about 20–29% of the measured value. Finally, results of the experimental program are used to identify sources of conservativeness and non-conservativeness in the current design methodologies used to calculate lateral forces imposed on non-yielding walls due to adjacent strip footing and suggested necessary modifications.

Fired-clay brick, cement-sand block and cement stabilized earth blocks are the most commonly used material for masonry construction in Sri Lanka. Strength, durability and cost are three major factors that influence the selection of material for wall construction. Even though Sri Lanka has a tropical climate, the benefits of insulating the external walls of the house are often not considered. Apart from thermal comfort of the internal environment, there is concern regarding increase in energy consumption. However, in recent years, as awareness of sustainable and green building concepts increased, interest in using sustainable and thermal comfort materials for house construction has increased. Because external walls play a major role in thermal insulation, there is a need to select suitable wall materials that can be energy efficient and reduce cooling load. Therefore, the present study aims to understand thermal comfort in house units constructed with commonly used wall material such as fired brick, cement-sand block and cement stabilized earth block. Temperature and humidity inside and outside house models were observed to compare the impact of masonry materials on thermal comfort. To compare the thermal comfort performance of the house models, three thermal comfort analysis models: steady-state comfort model, adaptive criteria model and deterministic models were used according to the British Standard European Norm (BS EN) 16798, CIBSE TM52 and ANSI/ASHRAE 55. Results show that house units constructed with cement stabilized earth blocks and fired-clay bricks are significantly more comfortable in terms of temperature and humidity variations. Energy-efficient house units thereby minimized energy consumption through reduction in indoor temperature. Therefore the cement stabilized earth block and fired-clay brick house model are found to be a suitable choice for construction.

The primary aim of transportation is to facilitate movement of people and goods in a safe and efficient manner. To meet the objectives of transportation, there are many challenges from an engineering perspective. Among them, geometric design is the foremost requisite in planning and functional design of a roadway system. In this context, operating speed plays a key role for controlling geometric design criteria and securing safe operational control. The operating speed varies according to locations and roadway characteristics if previous studies were anything to go by. It is found to be sensitive with regard to roadway types, terrain types, geometric design elements such as horizontal and vertical curves, and their combinations. In past studies, operating speed was observed to vary based on traffic control type and operational conditions. Many studies have determined operating speed for passenger cars and suggested models for evaluating traffic operational performance while showing inconsistency in geometric design. The present study provides a very comprehensive review of literature on the operating speed estimated under different roadway, geometric and traffic conditions across the nations. It is found that the operating speed studies performed under homogeneous and heterogeneous traffic conditions on multilane highways are limited and do not provide generalized solutions in terms of both safety and efficiency aspects. Thus, this study looks at operating speed and determining it by involving various geometric and roadway conditions and considering significant variables, data acquisition methods and equipment used and models for prediction. It highlights the need for future studies on operating speed characteristics, which is one of the major performance measures for evaluating roadway geometry consistency and traffic control performance.

This paper presents the study of treatment of an expansive soil with vegetal fibres. The soil studied is swelling clay from the region of Souk Ahras (Algeria). The use of fibres as reinforcement has shown a certain efficiency which increases the bond between the soil grains due to the friction between the soil particles and the fibre material. The vegetal fibres used are DISS crushed fibres. The influence of the vegetable fibre content on the global behaviour of the soil is studied; by highlighting the role of the inclusion rate of fibre in the soil mass (1, 2 and 3% of content by weight), this will be studied by a series of behaviour and mechanical performance tests. The DISS fibres have undergone chemical-thermal treatment to extract the sugars and soluble substances contained in the vegetal to avoid the decomposition of the latter in the soil. The results will be compared to those of unreinforced soil. Experimental results show that the swelling potentials are reduced by the addition of vegetal fibres, the cohesion of the soil treated is increased, and the soil is more ductile. It has also been shown that 2% of the DISS fibre content is a critical value for reducing the swelling potential of the clay soil.

Advanced remote sensing techniques are now capable of delivering more rapidly high quality information that is sufficiently detailed (and cost-effective) for many engineering applications. Here we focus on synthetic aperture radar (SAR), multi-temporal interferometry (MTI). With radar satellites periodically re-visiting the same area, MTI provides information on distance changes between the on-board radar sensor and the targets on the ground (e.g., human-made structures such as buildings, roads and other infrastructure). The detected distance changes are thus interpreted as evidence of ground and/or structure instability. In settings with limited vegetation cover, MTI can deliver very precise (mm resolution), spatially dense information (from hundreds to thousands measurement points/km2) on slow (mm-cm/year) deformations affecting the ground and engineering structures. Radar satellites offer wide-area coverage (thousands km2) and, with the sensors that actively emit electromagnetic radiation and thus can “see” through the clouds, one can obtain deformation measurements even under bad weather conditions. We illustrate the potential of high resolution MTI and explain what this technique can deliver to assist in infrastructure instability hazard assessment. This is done by presenting selected examples of MTI applied to monitor post-construction behavior of engineering structures. The examples are from Italy and include: an earthfill dam, an off-shore vertical breakwater built to protect an oil terminal, city buildings and a highway. We also stress that the current approach to the assessment of instability hazard can be transformed by capitalizing more on the presently underexploited advantage of the MTI technique, i.e., the capability to provide regularly spatially dense quantitative information for large areas where engineering infrastructure may currently be unaffected by instability, but where the terrain and infrastructure history (e.g., aging) may indicate potential for future failures.

The need to address the adverse effect of plastic waste on the environment as well as the increasing housing deficit in developing countries prompted this study. This paper reports the application of melted waste polyethylene terephthalate (PET) bottles as a binder for the production of polymer bricks. Melted waste PET bottle resin and natural sand were mixed at 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, and 1:8 PET/sand ratios by mass, and the mixture was cast in moulds to prepare the polymer bricks. The physicomechanical properties of the polymer bricks were examined for suitability of use as an alternative masonry unit. The study found that the compressive strength, flexural strength, and Poisson’s ratio of polymer bricks increased with sand content up to 1: 4 PET/sand ratio with values of 17.96 N/mm2, 9.01 N/mm2, and 0.34, respectively. The elastic modulus-to-compressive strength ratio reveals that polymer bricks produced with 1:3, 1:4 and 1:5 PET/sand ratios satisfied minimum requirement. Minimum sand content of 75 wt% is essential for substantial splitting tensile strength performance, and the maximum water absorption is 4.42% obtained for polymer bricks produced with 1:8 PET/sand ratios. Low sorptivity values of zero to 1.76 × 10−3 kg/(m2h0.5) were found, implying that polymer bricks could be used as a damp proof course.

The present study describes the dynamic tensile and compressive behaviour of concrete with respect to failure (damage) and material characteristics. The dynamic compression and tension tests were performed by using the Split Hopkinson Pressure Bar setup of 65 mm diameter of bars. The cylindrical specimen tested under dynamic loading conditions was ~ 30 mm in length with two different diameters (30 mm and 45 mm). The quasi-static compressive and splitting tensile strength of concrete was found to be 49.48 and 5.42 MPa, respectively. Dynamic testing showed a significant 78% increase in compressive strength as the strain rate increased from 1.33 × 10–4 to 284 s−1. Likewise, tensile strength increased by approximately 303.4% when the strain rate increased from 6.67 × 10–4 to 14.95 s−1, demonstrating concrete high strain rate sensitivity to dynamic tension. Under dynamic compression, the concrete strength increases due to the formation of the large number of cracks and high lateral confinement. In addition, the crushing density of concrete specimens has been increased with an increase in strain rate. During dynamic tensile failure, the specimen split into two semi-cylindrical pieces at low strain rate. Concurrently, localized crushing occurred at a high strain rate due to stress concentration at loading points. As the strain rate increased further, it intensified the localized crushing, ultimately giving rise to the formation of a wedge region followed by crushing zone.

When selecting the appropriate bridge deck construction system, it is essential to consider many criteria such as the span length, geographical location, construction speed, cost, site conditions, resource availability, technology, ease of construction, and service life. The objective of this study is to optimize the decision-making process for selecting a bridge deck construction system in the preliminary design and planning stage. The proposed model allows designers or decision-makers to make an informed choice of an appropriate construction system according to project criteria through a decision support system. The model employs value engineering methodology and a multi-criteria decision-making method and utilizes the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), a multi-criteria decision-making method. To gather modeling data from a focus group consisting of professional bridge engineers, a semi-structured interview and two questionnaires are conducted. When applying the proposed model to two active bridge construction projects in Egypt, it reveals that "Span by Span using launching girder" and "precast post tension girder" are better suited to cases one and two, respectively. The study makes a contribution by presenting a decision support system that combines value engineering methodology and a multi-criteria decision-making method (TOPSIS). This system empowers designers and decision-makers to make project decisions considering specific criteria and constraints.