2015 Symposium Abstracts - Civil Engineering

CE-01    Influence Of Temperature Induced Bond Degradation On Capacity Of Fire Exposed Reinforced Concrete Beams

Authors: Ankit Agrawal; Venkatesh Kodur

Abstract: Reinforced concrete structures, when exposed to elevated temperatures lose load carrying capacity due to degradation in mechanical properties as well as deterioration in the interfacial bond between concrete and rebars. The extent of bond deterioration influences stress transfer between concrete and causes a reduction in load carrying capacity of reinforced concrete members. In this paper, the influence of temperature induced bond degradation on response of reinforced concrete beams exposed to fire is investigated. A finite element based numerical model is developed in ABAQUS for tracing the response of reinforced concrete beams exposed to fire. The interfacial bond between concrete and reinforcing steel is taken into account using zero thickness bond-link elements consisting of two orthogonal springs to transfer shear and normal forces in the transition zone between rebar and concrete. The non-linear behavior of the bond-link element is defined using temperature dependent interfacial bond stress-slip models proposed in literature. Predictions from the model are compared against measured response parameters during fire tests. It is illustrated that interfacial bond between reinforcing steel and concrete can significantly influence response of RC beams exposed to fire, and thus needs to be accounted for in evaluating fire resistance of RC members.


CE-02    An Evolutionary Computational Approach For Damage Detection Using Self-Powered Wireless Sensor Data

Authors: Amir H. Alavi; Hassene Hasni; Nizar Lajnef; Karim Chatti

Abstract: A major limitation in implementation of self-powered wireless sensors pertains to a considerable loss of the sensed information. Consequently, interpretation of the limited but valued data generated by the self-powered wireless sensing technology becomes a challenging problem. To tackle this issue, this study presents an evolutionary computational approach for structural damage detection using the self-powered wireless sensor data. The proposed data interpretation system is based on the integration of a robust evolutionary technique, called gene expression programming (GEP), and finite element (FE) method. Several damage indicator variables are extracted upon the simulation of the compressed data stored in memory chips of a self-powered sensor. For the analysis, the complicated case of U10 gusset plate of the I-35W highway bridge in Minneapolis, Minnesota is considered. The gusset plate structure is analyzed as a 3D FE model utilizing Abaqus computer software. Various configurations are considered for the sensor number and locations. Subsequently, different damage scenarios are introduced to the plate and for each scenario and sensor configuration, a damage detection model is derived. Bases on a logistic regression analysis, probabilities are assigned to each model to find the most probable damage state. The damage detection models are presented as MATLAB and Visual Basic codes for further analysis. An uncertainty analysis is performed through the contamination of the damage indicator features with different Gaussian noise levels. The results indicate that the proposed method is efficiently capable of detecting different damage states in spite of high-level noise contamination.

This work was supported in part by U.S. Federal Highway Administration (FHWA)


CE-03    A Data Interpretation Algorithm For Structural Damage Detection

Authors: Amir H. Alavi; Hassene Hasni; Nizar Lajnef; Karim Chatti

Abstract: An innovative data interpretation system integrating finite element method (FEM) and probabilistic neural network (PNN) based on Bayesian decision theory is developed for damage detection. The proposed approach is established upon the simulation of the compressed data stored in memory chips of a newly developed self-powered wireless sensor. Several features extracted from the cumulative limited static strain data are used as damage indicator variables. Another important contribution of this paper is to define effective indicator variables that simultaneously take into account the effect of array of scattered sensors. This enables the method to detect damage at any location in a structure with an organized or a sparse random distribution of the sensors. The efficiency of the method is verified for the complicated case of U10 gusset plate of the I-35Whighwaybridge in Minneapolis. The beam and gusset plate structures are analyzed as 3D FE models utilizing Abaqus computer software. The static strain data from the FE simulations for different damage scenarios is used to calibrate the sensor-specific data interpretation algorithm. The viability and repeatability of the method is demonstrated by conducting significant number of simulations. Furthermore, a general scheme is presented for finding the optimal number of data acquisition points (sensors) on the structure and the associated optimal locations. A detailed uncertainty analysis is performed through the contamination of the damage indicator features with different Gaussian noise levels. The results indicate that the proposed method is efficiently capable of detecting different damage states in spite of high-level noise contamination.

This work was supported in part by U.S. Federal Highway Administration (FHWA)


CE-04    Experimental Analysis Of Damage Progression Using Self-Powered Wireless Sensors

Authors: Amir H. Alavi; Hassene Hasni; Nizar Lajnef; Karim Chatti

Abstract: This paper presents the results of a series of three-point bending tests on intact and damaged steel platesto studythe crack influence on the neighboring strain field. Several piezoelectric discs were installed to monitor the damage progression. A higher density of the piezoelectric discs was considered around the damage location to assess the neighboring strain field. Several displacement-controlled cycles with different frequencies and amplitudes were applied to the intact and damaged plates. It was observed that the discs located around the damage zone could efficiently capture the strain pattern increases and decreases due to damage progression. The results from these piezoelectric discs can be considered as an interesting tool for damage localization. That is to say, if the discs are not too far from the damage nor very adjacent to the damage zone, there would be a clear increasing or decreasingtrend to damage progression.Besides, several other tests were performed to check the minor changes in the boundary conditions (BCs) and test repetitions.

This work was supported in part by U.S. Federal Highway Administration (FHWA)


CE-05    Effect Of High-Temperature Creep On Response Of Concrete Columns Exposed To Fire

Authors: Saleh Alogla; Venkatesh Kodur

Abstract: Concrete columns experience significant deformations when exposed to fire due to the development of mechanical, thermal, transient, and creep strains. While the characterization and quantification of thermal and mechanical strains is well established for different concrete types, there is very limited data and models for high-temperature creep and transient strains. To show the rule of creep and transient strains in the response of concrete columns, two reinforced concrete columns are analyzed under fire utilizing a model developed using ABAQUS finite element program. In the model different creep and transient strain laws are considered to generate comparative structural responses and fire resistances of reinforced concrete columns based on strength failure criteria. Results from the numerical model shows considerable increase in the predicted fire resistance for reinforced concrete columns compared to experimental results when utilizing constitutive relationships that implicitly accounts for transient and creep strains of concrete. Including transient and creep strains explicitly also improves the numerical results of axial displacement variation with time of tested columns. The model also shows that utilizing different transient and creep strain models in the analysis shows considerable variability of the predicted fire resistance and axial displacement. Explicitly accounting for transient creep strains gives realistic fire resistances similar to the experimental results, while ignoring these strains in analysis yield very un-conservative fire resistances.


CE-06    New Displacement-Based Design Procedure For Ductile Reinforced Concrete Bridge Pier-Walls

Authors: Mansour Alturki; Rigoberto Burgueño

Abstract: Current seismic design provisions for bridge pier-walls are highly simplified and may lead to safety problems. The reason is that these provisions limit the in-plane response of pier-walls to the elastic range, which leads to higher design forces and increases the risk of brittle failures and construction costs. Statistical and numerical studies were carried out to develop a complete design procedure that employs the in-plane inelastic deformation capacity of pier-walls. Tests of statistical significance were conducted on experimental data from published literature to determine a lower bound limit for the displacement ductility capacity of pier-walls. Section analysis studies were also performed to study the effect of the sectional parameters on the effective yield curvature of pier-walls. New values for the displacement ductility demand (D) and the response modification factor (R) are proposed. These values are based on a refined definition that depends on the size ratios of pier-walls. A new expression for the effective yield curvature of pier-wall sections, which depends on sectional properties and the axial load level, is also proposed. Finally, a new displacement-based design procedure for pier-walls with ductile response is presented. The new design procedure leads to a direct estimate of the steel reinforcement ratio and employs the in-plane ductility capacity of pier-walls. Based on finite element analyses of the designed pier-walls, it was found that the new design procedure results in enhanced performance under seismic loading with lower reinforcement ratios.


CE-07    Response Of Fire Exposed Steel Bridge Girders

Authors: Esam Aziz; Venkatesh Kodur

Abstract: Fire is one of the most severe environmental hazards to which infrastructures may be subjected during their lifetime. Bridge fires can lead to significant economic and public losses. However, at present there are no specific fire resistance provisions in bridge design codes and standards to enhance structural fire safety of bridges. This work presents experimental and numerical studies on response of steel bridge girders exposed to fire. As part of experimental studies three steel-concrete composite girders were tested under simultaneous loading and fire exposure. Test variables included; load level, web slenderness, and spacing of stiffeners. A finite element model is applied to evaluate the critical factors that influence fire resistance of steel girders in bridges. Results from these studies indicate that a typical steel girder can experience failure under standard fire conditions in about 20 minutes. Also, numerical analysis results indicate that the time to failure and mode of failure in fire exposed steel girders is highly influenced by web slenderness, and fire intensity.

This work was supported in part by National Science Foundation


CE-08    Closed-Form Solution To P-Delta Effects On The Nonlinear Response Of Slender Reinforced Concrete Bridge Columns

Authors: Ata Babazadeh; Rigoberto Burgueño

Abstract: Reinforced concrete (RC) bridge columns are designed to perform beyond their elastic limits in the advent of moderate and strong earthquakes. Thus seismic energy is dissipated through inelastic deformations at the critical section of the column, known as the plastic region. The size of the plastic region and the magnitude of the inelastic demands over the region are affected by the column deformations (delta). The effect is intensified as the column slenderness increases since the slender columns exhibit exceptional flexibility that leads to significant vulnerability to member deformations and P-delta moments. In this communication, a closed-form solution to P-delta effects on the inelastic response of RC bridge columns is presented. The derivation of the solution was based on an equivalent elastic structure with a constant flexural stiffness for the cracked RC section that enables the solution to be independent of the global displacements. Formulas were derived to predict the length of the plastic region and the extent of P-delta effects on the inelastic response of slender RC columns. This led to the identification of a dimensionless slenderness parameter that measures the susceptibility of columns to P-delta effects. Experimental data from tests on large-scale slender columns were utilized to verify the results from the closed-form solution. It is demonstrated, through comparison between the test data and the obtained results, that the proposed formulas for estimating the magnitude of P-delta moments and the spread of the plastic region are accurate for small to intermediate inelastic lateral deformations.

This work was supported in part by National Science Foundation under Grant numbers CMMI-1000549 and CMMI-1000797


CE-09    Finite Element Modeling Of Temperature And Stress Development In Ultra-High Performance Concrete During Early Stages Of Curing

Authors: Pratik Bhatt; Venkatesh Kodur

Abstract: The development of mechanical properties in concrete is related to the hydration of the cementitious particles in the batch mix. Ultra-high performance concrete (UHPC) refers to a class of concrete with enhanced strength and durability properties, achieved by increasing the packing density of cementitious and filler constituents, use of very low water/cementitious ratios, and effective use of fibers. This low water/cementitious ratio often lead to higher rate of hydration leading to generation of large amount of heat of hydration during early stages of curing. This high heat of hydration, combined with relatively low thermal conductivity and surface cooling effects, often lead to high peak temperatures and large temperature gradients, especially in massive concrete blocks. This results in high thermal stresses leading to development of cracks in concrete. To minimize such cracking effective strategies needs to be developed. With a view to formulate such strategies, a thermo-mechanical finite element model is developed to evaluate the progression of temperatures, and stresses during curing of UHPC. Appropriate thermal and mechanical properties of UHPC are suitably incorporated in the model. The progression of temperature and stresses are studied for different sizes of UHPC blocks. Results from the study shows that temperature gradient and stresses increase with the increase in size of the UHPC block. The effect of thermal curing blankets often used to control the temperature rise and prevent the heat dissipation is also studied.


CE-10    Local Calibration Of The Rigid Pavement Performance Prediction Models Using Different Resampling Methods

Authors: Wouter Brink; Syed W. Haider; Neeraj Buch

Abstract: The local calibration of the performance models in the mechanistic-empirical pavement design guide (MEPDG) is necessary to support the implementation of the new pavement design methodology. The data requirements for the selected set of pavement sections from the PMS for local calibration include (a) a wide range of inputs related to traffic, climate, design and material characterization, (b) a reasonable extent and occurrence of observed performance data over time. This poster highlights the local calibration procedure for the rigid pavement performance prediction models using different resampling methods. Resampling methods such as, split sampling, bootstrapping, and jackknifing were used to locally calibrate the transverse cracking and IRI models. These resampling methods were used to study the variability of the model calibration coefficients. The bootstrapping method resulted in the lowest standard error for both performance models. The variability of the calibration coefficients were quantified for the repeated split sampling, jackknifing and bootstrapping methods. Bootstrapping provides more robust estimates of the calibration coefficients especially with small sample sizes. The comparison between the various resampling methods are summarized and presented for the locally calibrated models.

This work was supported in part by Michigan Department of Transportation


CE-11    Local Calibration Of The Rutting Model In The MEPDG

Authors: Wouter Brink; Syed W. Haider; Neeraj Buch

Abstract: The local calibration of the performance models in the mechanistic-empirical pavement design guide (MEPDG) is a challenging task due to the lack of needed data. The data requirements for the selected set of pavement sections from the PMS for local calibration include (a) a wide range of inputs related to traffic, climate, design and material characterization, (b) a reasonable extent and occurrence of observed performance data over time. This poster highlights the process for the local calibration of the rutting model in the MEPDG for Michigan conditions. The MEPDG rutting model predicts rutting in all pavement layers (asphalt, aggregate base and subgrade). The total rutting is a summation of individual rutting in all three layers. Ideally, field measurements of the individual layer rutting are required using destructive testing methods (trenching). Trenching all pavement sections in the calibration dataset is expensive and time consuming for a State Highway Agency. As an alternative to destructive testing, individual layer rutting was estimated using an approach developed in a previous study. The estimates of the individual layer rutting are important to accurately calibrate the rutting model. The rutting model was calibrated using estimated individual layer rutting and measured total rutting. It was found that the individual layer rutting calibration gave better results as compared to calibration based on total rut. This poster summarizes the methods used to locally calibrate the rutting models when trenching data are not available.

This work was supported in part by Michigan Department of Transportation


CE-12    Effect Of Diamond Grinding On Rigid Pavement Performance

Authors: Ronell Joseph Eisma; Syed Waqar Haider; Karim Chatti

Abstract: Diamond grinding is a rigid pavement preservation treatment used to restore pavement smoothness by correcting surface irregularities at cracks and joints. The treatment results in the reduction of dynamic loads which are the main contributors to load-related pavement damage. Numerous existing profile-based indices such as International Roughness Index (IRI) and Dynamic Load Index (DLI) quantify the change in surface roughness. Generally, diamond grinding treatment will minimize IRI and DLI by reducing the short wavelengths (2 to 50 ft) along a pavement profile associated with high frequencies that amplify dynamic axle loads. This study demonstrates the impact of diamond grinding on IRI and DLI and relates the index changes on predicted pavement performance in terms of faulting, cracking and roughness. A mechanistic-empirical pavement analysis was used to predict pavement performance. The profile and axle load data were obtained from the Long-Term Pavement Performance (LTPP) database for nine pavement sections treated with diamond grinding. The IRI and DLI of each pavement section were evaluated before and after diamond grinding. The gross-vehicle weight distributions for each section were then used to simulate dynamic truck response based on before and after grinding profiles. The resulting dynamic load spectra were used to predict pavement performance using the Mechanistic-Empirical Design Guide (MEPDG) models. The relationships were determined between changes in predicted pavement performance and profile-based indices. Such relationships can be used to establish performance related specifications for diamond grinding.


CE-13    Impact Of Site Factors On The Effectiveness Of Flexible Pavement Preservation Treatments

Authors: Ronell Joseph Eisma; Syed Waqar Haider; Karim Chatti

Abstract: Pavement preservation has become a common practice in the management of pavement network across the country. However, the effectiveness of the preservation treatments vary depending on numerous factors e.g., construction practices, traffic, climate and pre-existing surface and structural conditions. The purpose of this paper is to determine the impact of the site factors on the effectiveness of flexible pavement preservation treatments in terms of service life extension (SLE). The data from the Long-Term Pavement Performance (LTPP) SPS-3 experiment were utilized to compare the pavement SLE among different preservation treatments (slurry seal, chip seal, crack seal, and thin overlay) based on structural and functional performance measures. The SLE is a measure of treatment effectiveness and can be obtained by comparing the performance between treated and untreated control pavement section. The flexible pavement performance measures considered were structural and thermal cracking, rutting, and surface roughness, bleeding, raveling, and friction. The impact of various site factors (e.g., traffic, climate and pre-existing surface conditions) was determined by performing statistical analyses including analysis of variance (ANOVA) and multiple linear regressions. The comparison of SLEs among different treatments showed the most effective preservation treatment under different site factors. The results from statistical analyses elaborated the significance of site factors in defining the efficacy of various preservation treatments.


CE-14    Advanced Rapid Non-Destructive Test Method To Determine Chemical Composition Of Concrete Materials In The Field

Authors: Iman Harsini; Parviz Soroushian

Abstract: Maintenance of concrete infrastructure requires a great effort and cost. The cost of concrete reinforcement corrosion alone, in the US is about $125B/yr. ASR and other deterioration mechanisms are also a serious problem for the health of concrete infrastructure. Early detection of damage can prevent further deterioration of the structure and allows the state and federal agencies to save on maintenance money. The ultimate goal of this research is to develop a non-destructive platform that facilitates the diagnosis of deteriorated concrete by means of advanced chemical/physical analysis methods. This system consists of a portable apparatus that can be placed on any arbitrary surface and collects data from various depths of concrete. This device employes Nuclear Magnetic Resonance (NMR) to exploit information from the microstructure of concrete. This system is calibrated for different deterioration mechanisms at different progress levels of the damage. A software will be developed to analyze the output data to streamline the interpretations in the field.

This work was supported in part by Federal Highway Administration


CE-15    Analysis Of Damage Progression Due To Distortion-Induced Fatigue Cracking Utilizing Self-Powered Wireless Sensors

Authors: Hassene Hasni; Amir H. Alavi; Nizar Lajnef; Karim Chatti

Abstract: This paper is focused on a detailed analysis for the detection of damage progression for individual and a group of self-powered wireless sensors. This main goal is to find a reasonable relationship between the probability density function (PDF) parameters, i.e. μ and σ obtained from strain distribution, and damage progression. Different case studies are considered for the analysis including girder with fatigue cracking, girder with different crack lengths, and gusset plate with different crack lengths. Based on the results, for the sensors located far from the damage location, there is no notable sense of damage as the PDFs are fairly identical. The strain patterns remarkably change for the sensors close to the damage location and therefore the shape of the PDFs transforms. It is seen that μ and σ of the strain distribution, respectively, decreases and increases due to damage progression. The results for the group of sensors indicate that the standard deviation of μ and σ of group of sensors increases with damage progression. The results pertaining to the standard deviation of μ of group of sensors are slightly better indicators of damage progression compared to those for σ. It is possible to localize the damage with a group of sensors by checking of: (1) sensors that provide chaotic response when included in the analysis and (2) locations in which the incremental rates of the standard deviation of μ and σ of group of sensors notably decreases. Keywords: Self-Powered Wireless Sensor; Finite Element Method; Fatigue; Strain Distribution; Probability Density Function; Group of Sensors; Damage detection.


CE-16    Controlling The Postbuckling Response Of Cylindrical Shells Under Axial Compression For Applications In Smart Structures

Authors: Nan Hu; Rigoberto Burgueño

Abstract: Elastic instability, long considered mainly as a limit state or a safety guard against ultimate failure, is increasingly gaining a favorable regard. The paradigm shift deals with using the unstable response of slender structures for purposes that are rapidly increasing and diversifying, including applications for energy harvesting, frequency tuning, sensing and actuation. The structural prototype selected for this research is an axially compressed thin-walled cylindrical shell. Cylindrical shells can attain a higher number of snap-buckling events in their postbuckling regime due to the natural transverse restraint provided by their geometry, but harnessing such behavior for smart purposes is lack of extensive studies due to their notorious high imperfection sensitivity. This study explores three avenues to obtain multiple mode transitions in the elastic postbuckling response of axially compressed shells: (1) introducing seeded geometric imperfections (SGI); (2) introducing non-uniform stiffness distributions (NSD); and (3) providing internal lateral constraints (IC). Prototyped cylindrical shells were fabricated through 3D printing and tested under loading-unloading cycles. Numerical and experimental results have confirmed that the static and kinematic response of unstable mode branch switching during postbuckling response can be modified and potentially tailored.


CE-17    Backcalculation Of Swollen Crumb Rubber Modulus In Asphalt Rubber Binder And Its Relation To Performance

Authors: Anas Jamrah; M. Emin Kutay; Sudhir Varma

Abstract: A method for estimating the engineering properties of swollen rubber particles within crumb rubber modified asphalt binders is provided. It was observed that the backcalculated modulus of swollen rubber within the crumb rubber modified asphalt binder is related to the performance. Therefore, improper mixing temperatures as well as interaction times can lead to insufficient swelling of rubber and performance worse than anticipated of the crumb rubber modified asphalt mixtures. The backcalculated modulus of the rubber within can be used as a quality control measure during construction. An experimental approach was undertaken to investigate the mechanisms of interaction between the asphalt binders and crumb rubber and their effect on the modulus of the rubber within the crumb rubber modified asphalt binder. The experimental program included Dynamic Shear Modulus (|G*|) as well as Linear Amplitude Sweep (LAS) tests. These tests were performed on neat binder, crumb rubber modified binders mixed at three different temperatures, neat binder mixed at these three different temperatures (without the rubber) and the residual binder obtained by draining the crumb rubber modified binders (i.e., filtering out the rubber particles). In addition to the experimental approach, a 3D Finite Element based micromechanical model of the |G*| test was developed using the ABAQUS software. The FE model provides insight on the relationship between the microscale and macroscale material behavior, i.e., the stiffening and softening effects of rubber in crumb rubber modified asphalt binders.

This work was supported in part by Michigan Department of Environmental Quality


CE-18    Binder Softening Effect Of Crumb Rubber Modifier For High Percent Reclaimed Asphalt Pavement (RAP) Mixtures

Authors: Salih Kocak: M. Emin Kutay

Abstract: The importance of using recycled materials in any industry has been increasing recently all over the world. Recycling old asphalt pavements and incorporating them in the new mixtures is one the major practices in asphalt industry. The use of recycled/reclaimed asphalt pavement (RAP) provides not only economic but also environmental benefits. Increasing the percentage of RAP in a new hot mix asphalt (HMA) may hinder the economic benefits due to the necessity of expensive softer binders used to compensate RAP stiffening effect. Alternatively, this problem can be successfully overcome by use of another recycled material; crumb rubber (CR). This paper compares the thermal and fatigue cracking performances of the mixtures prepared with rubberized, softer and base binders. The binders compared were devulcanized rubber modified, crumb rubber terminally blend modified, crumb rubber by wet process modified, soft binder (PG 58-34) and base binder (PG 58-28). The results of the performance tests indicated that CR modification could provide the desired softening behavior to high percentage RAP mixtures. The mixture utilized CR modification by wet process was observed to outperform other mixtures in both low temperature and fatigue cracking resistance.

This work was supported in part by Michigan Department of Environmental Quality


CE-19    Geopolymer Concrete: A Sustainable Alternative To Portland Cement Concrete

Authors: Faris Matalkah; Parviz Soroushian

Abstract: Portland cement manufacturing is responsible for about 7% of carbon dioxide emissions and 4% of energy use worldwide. The Portland cement chemistry also lacks the versatility to enable value-added use of broad categories of industrial wastes (e.g., biomass combustion ash) that are becoming available with adoption of more sustainable industrial practices. This project employs an alternative inorganic binder chemistry for production of concrete. This binder chemistry, based on alkali aluminosilicate hydrates, offers the potential to significantly lower the carbon footprint and energy content of concrete. It is also highly robust, and can made value-added use of diverse industrial wastes which are not compatible with the chemistry of ordinary Portland cement. The project emphasizes value-added use of biomass combustion ash in concrete materials embodying the new binder chemistry. More specifically, the high silica and alkali contents of non-wood biomass ash are used as chemical constituents contributing to the development of aluminosilicate-based binders in concrete production. Refined concrete chemistries are developed where the alkali and silica contents of non-wood biomass ash are supplemented by the addition of alumina-rich constituents to produce a balanced chemistry for production of ‘non-wood biomass ash-based concrete’. The new inorganic binder offers significant advantages over the ordinary Portland cement binder in terms of moisture barrier qualities, weathering, chemical and fire resistance, stabilization of hazardous wastes, carbon footprint, energy content, and initial and life-cycle economy.

This work was supported in part by U.S. Department of Agriculture


CE-20    Effective Pavement Condition Rating Systems

Authors: Gopikrishna Musunuru; Gilbert Baladi; Tyler Dawson; Jane Jiang; Michael Prohaska

Abstract: Existing pavement condition rating systems are mainly based on the current pavement conditions and/or distresses. These systems do not account for the pavement’s deterioration rates. For instance, two pavement sections rated fair this year, may or may not have similar rating next year. A balanced and comprehensive pavement condition rating system should be based on the pavement’s conditions and distresses and its deterioration rates. On a research study, sponsored by the Federal Highway Administration (FHWA), dual pavement condition rating systems were developed based on the pavement's functional and structural aspects and rates of deterioration. These rating systems account for current and future pavement conditions and distresses. Therefore, they provide more accurate information to the decision makers regarding the management of the pavement network while being simple enough for communication with legislators and the general public. The functional rating is based on ride quality (International Roughness Index, IRI) and safety (skid resistance and rutting), and is expressed by the Remaining Functional Period (RFP). The structural rating is based on cracking, faulting, and rutting and is expressed by the Remaining Structural Period (RSP). The RFP is defined by the shortest time in years between now and the year when one of the conditions reaches its threshold value. Similarly, the RSP is the shortest period in years between now and when a threshold is reached. The main advantage of the RFP and RSP is that both are proportional to the elapsed time. Their values decrease by one year for each calendar year.

This work was supported in part by Federal Highway Administration


CE-21    Water Quality Improvement Through Proper Design And Construction Of Wastewater Collection Systems And Sanitation Facilities In Dar Es Salaam,Tanzania

Authors: Tula Ngasala; Susan Masten

Abstract: In many developing countries, water scarcity and wastewater management are amongst the greatest challenges, especially in urban low income areas where houses are in close proximity to each other and none of the sanitation facilities are built to minimize contamination. There are no standard designs available for the construction and operation of toilets and bathing facilities. The study area selected for this research is the small part of urban area in Dar es Salaam, Tanzania. The objective of this study is to improve water quality through proper design and construction of wastewater collection and sanitation facilities. The annual mortality rate is 175 deaths per 1000 children, predominately due to waterborne diseases that affect children. This community has a very low income and members spend nearly 70% of their income to purchase water for domestic use and for wastewater management. Water is most often purchased from street vendors who sell water of unknown origin and purity. A limited study conducted summer of 2014 revealed that drinking water samples collected from domestic wells, city water, and from vendors had 40-160 mg/L nitrate-N (WHO standard for drinking water: 11 mg/L-N) which indicates contamination by sewage. Wastewater samples collected from water bodies around the area showed that they are highly contaminated by fecal sludge and wastewater from both household and industries. About 30 households from the study area were surveyed and results showed that there was a great financial burden because of purchase water for domestic use and emptying sewerage from their collection systems.


CE-22    Development Of An Acceptance Test For Chip Seal Projects

Authors: Ugurcan Ozdemir; M. Emin Kutay

Abstract: Chip Seal is one of the major asphalt pavement preservation techniques. The function of an asphalt chip seal is to form a new layer above the existing pavement and prevent water infiltration. It also improves the surface texture, which enables the pavement to have better skid resistance. The aggregate embedment into the binder is one of the most significant parameters during the design process of the chip seal. The embedment depth should be 50% after initial rolling, and 70% embedment after 2 or more weeks of traffic. Asphalt chip seals having the embedment depth less than 50% are more susceptible to aggregate loss due to insufficient bonding between binder and aggregate; whereas, asphalt chip seals having the aggregate embedment higher than 70% may cause bleeding problems on the surface of the pavement (Gransberg, Karaca, & Senadheera, 2004). The goal of this project is to develop a standard test procedure to directly calculate aggregate embedment depth into the asphalt binder in a chip seal project via digital image analysis. The overall approach involves coring asphalt chip seal samples from field, capturing images of vertical slices and using automated image analysis techniques to compute the percent embedment . Premature distresses such as bleeding and aggregate loss can be prevented if such a standardized test procedure is developed and implemented.

This work was supported in part by Michigan Department of Transportation


CE-23    Analysis Of The Effects Of Sub-Layers And Roadbed Materials On Pavement Conditions And Distresses

Authors: Michael Prohaska; Gilbert Baladi

Abstract: The accurate modeling of pavement performance is dependent on a thorough understanding of the mechanisms of pavement conditions and distresses and the impacts of each aspect of pavement design and pavement treatments on their magnitudes and rates of change. This project utilizes the Long-term Pavement Performance (LTPP) database to verify section design and identify pavement sections having sufficient time series pavement conditions and distresses data to model their rates of change. Comparative analysis on the effects of base, subbase, and subgrade soil types on these rates of change will be conducted. First, the LTPP data will be sectioned by state, climatic conditions, and traffic level and then the sensitivity of the pavement conditions and distresses and their rates of change to each sub-layer type. The key in this study is to determine the most adequate analysis methods by which potential correlations between the dependent (pavement conditions and distresses) and independent variables (material, pavement section, and treatment types) can be identified. Results of preliminary analyses of these potential correlations will be presented. The presentation will concentrate heavily on treated pavement sections.


CE-24    A Process-Based Distributed Model Applied To Study The Hydrology Of The Kalamazoo River Watershed

Authors: Han Qiu; Mantha S. Phanikumar

Abstract: The Kalamazoo River watershed drains 2,020 square miles in southwestern lower Michigan and is one of the most important agricultural watersheds in Michigan. Recently there has been heightened interest among residents and governments in this region in water resources management and sustainable growth. The aim of my research is to apply a process based distributed model- PAWS_CLM to study the hydrology of Kalamazoo River watershed. The PAWS_CLM model has a holistic structure of hydrological processes and possess structured data assimilation and integration algorithms and good computational efficiency. The model performance was evaluated by multiple datasets, for example river discharge, evapotranspiration, soil moisture and groundwater head to execute the multiple hydrologic controls. The model results showed good overall performance in simulating the river discharge in a 7 year simulation period and the generated evapotranspiration outputs compared well with MODIS (Moderate Resolution Imaging Spectroradiometer) products. The long term steady groundwater head matched well with the Well-logic database and the soil moisture and soil temperature time series got decent comparisons with the MAWN (Michigan Automated Weather Network) station data.

This work was supported in part by US Department of Agriculture


CE-25    Semi Empirical Frost Heave Model

Authors: Pegah Rajaei; Gilbert Y. Baladi

Abstract: Frost heave refers to the uplifting of the ground surface caused by the formation of ice lenses within the soil layers in winter season. For frost heave to occur three conditions are required: Frost susceptible soil, water source and below freezing temperature. The ice lens growth can cause uplift in pavement structure, shoulders, unprotected foundations of bridges and utility lines leading to extensive damage. The frost heave rate and magnitude can be predicted using capillary and frozen fringe theories. Unfortunately, both theories are controversial. The limitations of capillary theory lead to inaccurate prediction of frost heave. Whereas, the frozen fringe theory requires complex models with various input variables that might be unavailable and/or expensive to collect. In a research study sponsored by the Michigan Department of Transportation (MDOT), one of the secondary frost heave models were modified and evaluated based on field data. A statistical frost depth model which is developed during the study based on the frost depth data in the States of Michigan was used in the modified model. Using the statistical frost depth model simplifies the analytical solution and yields more accurate results. Lastly, the modified model accuracy was verified using the pavement and shoulder frost heave data in the State of Michigan.

This work was supported in part by Michigan Department of Transportation


CE-26    A General Model For Prediction Of Frost Depth

Authors: Pegah Rajaei; Gilbert Y. Baladi

Abstract: In cold regions where air temperature drops below 32F for extended periods of time, Frost depth is an important factor that affects the design of all infrastructures including pavements, building and bridge foundations and utility lines. Frost depth depends on the type of the materials, their thermal properties, water content, and climate condition, such as air temperature, wind speed, precipitation and solar radiation. Different numerical or analytical models can be used for prediction of frost depth, but the input data for such models are sometimes unavailable or/ and expensive to collect. In a research project sponsored by the Michigan Department of Transportation (MDOT), soil temperature data from Road Weather Information System (RWIS) in the Michigan State were used to evaluate the accuracy of existing frost depth prediction models such as Stefan model (Stefan, 1889), Modified Berggren model (Aldrich et al 1953), Chisholm and Phang empirical model (Chisholm and Phang, 1980) and U.S Corps of Engineers empirical model (1984). Since none of the models results were satisfactory, revised empirical models were developed. The only required input for these models is air temperature. The results showed better agreement with field data in comparison to the previous models. Furthermore, the accuracy of the models was verified by using the frost depth data in the State of Minnesota. Finally, by combining the models using the measured thermal conductivity values for different soil types and air temperatures as inputs, a general model was developed.

This work was supported in part by Michigan Department of Transportation


CE-27    Pavement Surface Characterization For Optimization Of Trade-Off Between Grip And Rolling Resistance

Authors: Shabnam Rajaei; Roozbeh Dargazany; Karim Chatti

Abstract: Understanding the interaction between pavement and tire surfaces is of great importance since it can improve the perception of friction, rolling resistance, wear, interior and exterior noise, splash and spray and thermal conductance between these surfaces. Friction plays an important role in vehicle safety while rolling resistance can affect fuel consumption of the vehicle. Several factors influence these two phenomena, which in this study the effect of tire properties and pavement surface characteristics are taken into account. An optimal method is demonstrated to characterize the surface properties that yield the least rolling resistance without sacrificing grip in the process. Experimental studies will be done for obtaining comprehensive measurements of different sets of surface texture (from micro-texture to unevenness), their rolling resistance and friction.


CE-28    Circulation And Transport In The Gull Lake: Field Observations And Modeling

Authors: Ammar Safaie; Mantha Phanikumar

Abstract: Gull Lake is a large (8 km2 surface area) and deep (34 m maximum depth) clear water lake in southwestern Michigan in Kalamazoo County. While considerable limnological research of historical significance was conducted on the lake, no numerical model has yet been developed to simulate physical and biological dynamics in the lake. Our aim is to create a coupled biophysical model of Gull Lake to understand hydrodynamic and ecological processes such as nutrients and algal blooms. A new three dimensional, unstructured grid hydrodynamic model of Gull Lake was created. This hydrodynamic model was tested using ADCP (Acoustic Doppler Current Profiler) current measurements. In the summer of 2014, we deployed two ADCPs for the first time in the lake, and we were able to successfully obtain high-resolution current and temperature data using the ADCPs. Comparisons between model results and observations show that the model does a reasonable job, but an accurate bathymetry is needed in order to improve the performance of the numerical model. Additional field data will be collected in the summer of 2015 to further refine the coupled models.

This work was supported in part by National Science Foundation


CE-29    Structural Assessment And Damage Identification Algorithms Using Binary Data

Authors: Hadi Salehi; Rigoberto Burgueño

Abstract: One of the challenges in structural health monitoring (SHM) is the power required for sensors to collect and communicate data. Self-powered sensors are able to harvest power by from their environment, i.e., strain and vibration of the host structure. However, the harvested power still limited and improving the system’s efficiency requires reducing the power budget. A way to minimize the communication power demand is to transmit the minimum amount of information, namely one bit. The binary event generated at each sensor node depends on a local rule based on physical measurements, but interpretation of at the global level requires dealing with discrete binary (1 or 0) data with reduced resolution. This study investigates approaches for the interpretation of binary data for structural assessment and damage identification. Different pattern recognition (PR) methods based on image data analysis were adapted for the study. The methods were evaluated through the finite element simulation of an aluminum plate subjected to cyclic loading. Simple pilot-type local rules for binary event generation were defined in terms of displacements and strains at the sensor nodes. The ability for each of the PR methods to identify service demands, load variations and localized material degradation was evaluated. Results indicate that PR methods can be used as damage identification algorithms for binary data sets. Future directions for the work include the definition of enhanced local rules for event generation and linking the binary data patterns to mechanics-based rules in order to extract parameters related to structural and material properties.

This work was supported in part by National Science Foundation


CE-30    Modeling Shear Failure In Precast Prestressed Concrete Hollowcore Slabs Under Fire Conditions

Authors: Shakya Anuj; Kodur Venkatesh

Abstract: Prestressed concrete hollowcore slabs when exposed to fire, as encountered in buildings, are susceptible to failure under shear limit state. However, current approaches do not consider shear limiting state in evaluating failure of hollowcore slabs under fire conditions. This paper presents an approach for modeling the response of PC hollowcore slabs by taking into consideration shear limit state. A three dimensional finite element model is developed for evaluating failure of fire exposed prestressed concrete (PC) hollowcore slabs under various limiting states, including through shear. This nonlinear finite element model, developed in ANSYS, utilizes a transient thermo-structural analysis to trace the response of typical hollowcore slabs under fire conditions. The model accounts for temperature induced degradation of properties of concrete and prestressing strands, cracking in concrete, material and geometrical nonlinearities, realistic fire, load and restraint conditions, as well as different failure limit states. In order to predict failure due to concrete damage in hollowcore slabs, the model utilizes concrete plasticity model proposed by Willam and Warnke. The validity of the model is established by comparing temperature, deflection, fire resistance and failure mode from the numerical model with data obtained from fire tests. Results obtained from parametric study show that slab depth, axial restraint, loading pattern and fire scenario have significant effect on the shear behavior of PC hollowcore slabs exposed to fire.

This work was supported in part by 2012-13 Daniel P. Jenny Research Fellowship (PCI)


CE-31    Performance Evaluation Of Pre-Swollen Crumb Rubber Modified HMA Mixtures

Authors: Sepehr Soleimani; M. Emin Kutay

Abstract: Adding crumb rubber to Hot Mix Asphalt (HMA) mixtures whether as a part of its aggregate stones (dry process) or binder modifier (wet process) improves its performance. Pre-swollen rubber improves the behavior of the mixture, without absorbing the light components in the asphalt binder during mixing. In this research, the influences of using pre-swollen rubber on the mixture performance are investigated. The concern of using this material is to identify potential benefits of enhancing the performance of the mixture in rutting (high temperature behavior) and cracking (low temperature behavior). To evaluate the changes, a laboratory investigation has been conducted on two types of asphalt mixtures containing 0% pre-swollen CR (control), and 20% pre-swollen CR and their complex dynamic moduli (|E*|) have been determined. The measured |E*| master curves were used in a moving load algorithm to determine the strain levels at the bottom of the HMA layers. Results showed that the strain at the bottom of the modified HMA layer was larger than the strain for the control mixture. The measured |E*| values will be used for a full analysis and performance prediction (rutting, fatigue cracking, thermal cracking and IRI) using the M-E PDG software.


CE-32    Influence Of Ageing On Hot Mix Asphalt Concrete Properties In Pavements

Authors: Sudhir Varma; M. Emin Kutay

Abstract: Chemical and physical changes in properties of hot mix asphalt (HMA), caused by construction and in-service use may significantly affect pavement performance. The objective of this research focused on determining the effect of ageing on characteristic properties of HMA. Traditionally, ageing in asphalt mixtures is investigated using two approaches: (1) interpolating the ageing potential of asphalt mixtures based on ageing potential of asphalt binders (2) interpolating the ageing potential of asphalt mixtures based on laboratory ageing of asphalt mixtures under different ageing conditions. However, both the methods fail to account for in-situ field conditions such as compaction, air voids and influence of aggregates. In this study, a new methodology is suggested that allows investigating ageing in in-service pavement using data obtained from commonly used Falling Weight Deflectometer Test (FWD). FWD test data over 10+ years from eight different test sections were used in the study. A genetic algorithm based viscoelastic backcalculation model was used to backcalculate both viscoelastic pavement layer properties (dynamic modulus) as well as the time-temperature shift factors from the FWD test data. The investigation focused on quantifying the effect of aging in dynamic modulus and time-temperature properties of HMA. Preliminary investigation indicated that the proposed method was able to show the as expected age stiffening effect in the viscoelastic properties of HMA in most of the test sections.