Civil Engineering Infrastructures Journal
Volume:54 Issue: 2, Dec 2021

The rapid drawdown condition to control floods and irrigation is one of the things that may occur over the lifetime of the dam. Also, the stability of the dam at the rapid drawdown will be more important due to the faster reduction of the water level of the dam reservoir than the pore water pressure. In this study, the finite element method and GeoStudio software used to study the seepage from the body earth dam. Also, the complete elastic-plastic model of Mohr-Coulomb is considered in the analysis. In this study, the stability analysis of the Eyvshvan earth dam after rapid drawdown due water to release of the dam reservoir to downstream agricultural lands during drought crisis, is investigated. For the validation, first, the results of the pore water pressure instrument were compared with the results of numerical analysis. The results of multivariate regression analysis (coefficient of determination) showed very good agreement (R2=0.98). The results showed that the phreatic line remains after 29 days from the start of the rapid drawdown of the reservoir, while half of the volume of the drained reservoir remains at 1842 masl (1/3 of the crest). The analysis of dam stability during rapid drawdown using both Morgenstern-Price and Bishop Methods showed that the most critical situation would occur after 42 days of discharge with a factor of safety (FoS) of 1.71, with no stability hazard and the upstream slope would be safe.

The deterioration of existing road pavement surfaces over the years due to aging and the growing number of heavy vehicles has become an important issue. Roads require appropriate maintenance to keep providing the target service. Many efforts have been made by road engineers to maintain road pavement surfaces; however, there are some problems due to costs, including vehicle running costs. Therefore, there is a need for an efficient and low-cost system to facilitate evaluation of the serviceability of existing road pavement surfaces. This study aims to develop an efficient, rational and useful method or system that can be used to perform a visual assessment of the condition of not only the pavement but also road structures, including slopes, vegetation and equipment such as guardrails, curbs and guideposts. Such a system should be inexpensive and be IT-based by making use of new information and the latest technologies. In addition, a method based on an analytic hierarchy process is employed in the decision-making process to analyze a complicated decision problem based on video files obtained by the system.

Change in modal strain energy is one of the indicators used to detect damage in structures. However, in structures with high degrees of freedom, such as double-layer grids, this method requires a relatively large number of mode shapes which in practice is difficult to determine. Therefore, it is necessary to reduce the number of required mode shapes. In this study, a damage detection technique based on modal strain energy and Dempster-Shafer evidence theory is presented for locating damage in double layer grids using only a few number of mode shapes. First, by calculating mode shapes of the grid in undamaged and damaged states, the modal strain energy based index for each mode shape is determined. Then, the results obtained from separate mode shapes are combined using Dempster-Shafer theory to achieve better results. In order to investigate the effect of noise on damage detection, 3% random noise is added to mode shapes. To demonstrate the performance of the proposed method, different single and multiple damage cases with different damage intensities are considered. Numerical results show that using 5 mode shapes, the presented technique can detect up to 3 damaged elements with different damage intensities in different parts of the grid with good accuracy (probability of 92.3%). Considering the fact that the classical modal strain energy method fails to distinguish even 1 damaged element in the double layer grid, the result shows significant improvement.

Determination of tunnel support, required for tunnel stability and safety, is an important debate in tunnel engineering field. Q-system classification is a technique used to determine the support system of a tunnel in rock. The problem is that all the required parameters of support system are not accessible. On the other hand, such accesses are very costly and time consuming. Therefore, it is impossible to determine the Q-value in all cases. This paper identifies the most influential parameters of Q-system using SPSS program. Then, it adopts multi-variable regression (MVR) and genetic algorithm (GA) methods to propose a relation for predicting the Q-value using three influential parameters. To this end, 140 experimental data are used. To assess the obtained models, 34 new experimental data, which are not in the primary dataset, are used. The innovation of this paper is that instead of six parameters, the Q-value is determined using three parameters with the highest impact on it instead of six parameters. In this study, the MVR model, with RMSE = 2.68 and correlation coefficient = 0.81 for train data and RMSE = 2.55 and correlation coefficient = 0.80 for test data, showed better performance than GA model, with RMSE = 2.90 and correlation coefficient = 0.82 for train data and RMSE = 2.61 and correlation coefficient = 0.84 for test data.

The implementation of Building Information Modeling (BIM) in the Architecture, Engineering and Construction (AEC) industry is growing rapidly. The Oil, Gas and Petrochemical industry (OGPi), however, is still lagging in harnessing the BIM capabilities. Therefore, the main question of this research is: How and what actions should be adopted for deploying BIM in the OGPi? The research is divided into three parts as an action research. This study investigates the second part, namely preparation of an adoption roadmap for deploying BIM in collaboration with Integrated Project Delivery (IPD) in the OGPi. To achieve this goal, an extensive literature review including the most established roadmaps in the AEC industry and also the semi-structured interviews with the OGPi's experts are conducted.  Then, an adoption roadmap is derived for OGPi via Innovation Diffusion Theory (IDT), ‘Why, How, What’ questions (Sink model), strategic planning and innovation roadmap as well as the iterative process in the studies and interviews. The prepared roadmap validated by triangulation through focus group meetings and oils the wheels of BIM implementation alongside with IPD in the OGPi firms to grabs BIM merits and harness its challenges. Finally, the major limitations and the required future studies are addressed.

Road accidents are one of the ten major causes of death in the world. Lack of enough friction and skid resistance of the pavement surface are known as important factors in traffic accidents. In this study, to evaluate the relationship between skid resistance and pavement surface macrotexture, five methods of creating macrotexture on concrete pavements were used. Sand Patch test, British Pendulum and Wide Wheel Abrasion tests were employed to obtain mean texture depth, skid resistance and abrasion resistance of the surface, respectively. Results showed that brushing on fresh concrete surface (parallel or perpendicular to the traffic direction) can improve frictional properties of pavement surface, drastically. This method increased British Pendulum Number (BPN) and friction coefficient by 32% and 38% (in average), respectively. Friction coefficient of parallel brushing was quite similar to perpendicular (0.2% discrepancy), while its abrasion resistance was 4% higher. Hence, as a finding, parallel brushing is the most recommended texturing technique in respect to friction. Generally, concrete pavement texturing decreases surface abrasion resistance, but burlap dragging improved this index by 2.5%. Nevertheless, burlap dragging results could be deceptive due to the high sensitivity to initial setup conditions. In other words, measurement scale of the studied testing procedures are small in respect to the scale of protuberances caused by burlap dragging method.

A bonded concrete overlay consists of a new concrete overlay placed directly on top of an existing concrete pavement. The properties of such layer have a distinguished factor for reliable service-life extending of concrete pavements repairing systems. In this paper, the engineering properties of cold-drawn crimped-end steel fiber reinforced (CFCSF) concrete mixtures as overlays are evaluated. To this end, CFCSF mixtures are made with fiber contents of 15 and 25 kg/m3 with diameters of 0.8 and 1 mm and water-cement ratio of 0.5 in comparison with reference concrete. The engineering properties of these types of concrete in the properties of the fresh and the hardened concrete including Compressive Strength (CS), Tensile Strength (TS), flexural strength (FS), Modulus of Elasticity (ME), depth of Water Penetration (WP), Impact (IR) and Abrasion Resistance (AR) are investigated. The results show that at an early age, the addition of fibers had no significant effects on the CS but at higher ages, the samples containing steel fibers have higher compressive TS and FS than the control ones. Also, the use of steel fibers increases the ME, IR and AR of CFCSF specimens. Moreover, models are developed to correlate the mechanical properties of mixtures with AR and IR. The comparison between the relation of AR and IR to other mechanical properties, made of the linear regression and polynomial relationships in aspects of R2, indicates that stronger relations are available between TS with IR and AR with ME.

In this paper, the performance of soil nailed walls with various nail patterns has been studied to find an optimum layout based on the deformation criterion. To this end, parametric analysis on soil nailed walls with various nailing patterns is performed. Nine patterns including one uniform and eight variable nails length are considered. For each pattern, parametric analysis on different parameters including wall height, surcharge, nails spacing is implemented to find an optimum pattern based on the deformation criterion. The simulation results indicate that using the variable layout with long nails at the top of the wall not only reduces the lateral deformation of soil nailed wall but also decreases the density of nails.

Bridges play a critical role in the transportation system network; accordingly, assuring satisfaction with the service level of these structures is vital for bridge maintenance managers. Thus, it is vital to determine the optimum bridge maintenance plan (i.e., the optimum timing and type of repair activities applied to the bridge elements) considering the budget limitations. To optimize the bridge maintenance plan, some researchers have focused on developing optimization models, including the Genetic Algorithm (GA). However, a few studies have employed Bridge Information Modeling (BrIM) to enhance bridge maintenance management. This study focuses on developing an integrated framework based on BrIM and bridge maintenance optimization to utilize visualization capabilities of BrIM to assist maintenance managers in making decisions. The presented framework optimizes the bridge maintenance plan at the sub-element level. The BrIM automatically feeds into the developed GA optimization system. The introduced framework is successfully verified using a real-world case study.

Over the previous years, the use of structure roof systems which can be implemented with long column spans has been welcomed by manufacturers. One of the most widely used roofs is the waffle slab system. Therefore, by reviewing previous studies in the field of roof collapse in reinforced concrete structures under blast, the absence of studies on the performance of waffle slab and comparing its behavior with blast affected RC slabs is observed. Laboratory simulation of this problem requires high cost, high accuracy in model building and much time. In this study, after preliminary model validation with experimental research and two numerical studies in LS-DYNA software, the behavior of waffle slab subjected to blast load and compare its performance with RC slab are investigated. It should be noted that because the blast load is applied to the structure in a very short time, it has a high loading rate. Therefore, the strain rate effects on concrete and reinforcement are considered for achieving real material behavior. The identical volume of concrete and reinforcement used in all roofs is considered in order to evaluate and compare the behavior of the roofs reasonably. Then, the effect of the geometric dimension of waffle molds and the effect of the supporting condition on the Waffle slab responses are studied. Other investigated parameter in this study includes the effect of concrete compressive strength on the behavior of roof under blast load. The mass of the explosive and its distance from the roof surface are other parameters considered in this study. The effect of bar size on the behavior of the roof is also investigated. The results of this study are presented as diagrams and tables showing that given the same volume of concrete and reinforcement in the RC slab and the waffle slab, the central displacement of Waffle slab is reduced to a desirable level. This shows the better behavior of the waffle slab in comparison with the RC slab with the same volume of material under the blast load.

In this article, a Dynamic Material Flow Analysis (DMFA) model is presented that characterizes the stocks and flows of cement from 1963 to 2063 in Iran. Using cement consumption data for the period of 1963-2018 an attempt is made to provide reliable estimates of the present as well as future cement in-use stocks and discards (from 2019 to 2063) to relevant stakeholders such as the Ministry of Road and Urban Development, Department of Environment, public and private utilities, and the construction and cement industries. Based on a normal lifetime distribution, a flow dynamic model is developed for each cement end-use category including buildings, infrastructures and others. Each sub model is simulated with 9 scenarios made from combinations of 3 scenarios for future cement consumption growth rate and 3 scenarios for the mean lifetime of the structures. For the base scenario, the model-derived estimate of in-use cement stock and cumulative discard for the year 2063 is 2191 million metric tons (Mt) and 1856 Mt, respectively. Such a great discard should be considered in policy making for better life cycle management of cement in Iran. The main finding of the paper is that by increasing the mean lifetime of the structures (especially buildings), the amount of cumulative cement discard in 2063 can be drastically decreased (generally over 50%) and this decrease will not be affected considerably by the cement consumption growth rate in the future. So this can be a reliable strategy for the sustainable life cycle management of infrastructures in Iran.

In this study, the seismic response of tall concrete structures with a special dual frame-wall concrete system is investigated using the endurance time method, and the results are compared with nonlinear time history analysis results. For this purpose, first, appropriate analytical models including buildings with concrete framed-wall system and 20, 30, and 40 stories are modeled non-linearly in PERFORM 3D software, and then, main nonlinear time history analyses are carried out for seven ground motions (accelerogram) further from the fault based on the FEMA P695 code and the endurance time accelerogram of (in) series. The results of the analysis are compared using indices (shear, relative displacement, and acceleration). The results indicate that the endurance time method is accurate in two indices of shear and acceleration, but the accuracy of the relative displacement index of the floor decreases as the number of stories of the structure increases.