Showing papers in "Journal of Engineering Mechanics-asce in 1998"

Plastic-Damage Model for Cyclic Loading of Concrete Structures

Abstract: A new plastic-damage model for concrete subjected to cyclic loading is developed using the concepts of fracture-energy-based damage and stiffness degradation in continuum damage mechanics. Two damage variables, one for tensile damage and the other for compressive damage, and a yield function with multiple-hardening variables are introduced to account for different damage states. The uniaxial strength functions are factored into two parts, corresponding to the effective stress and the degradation of elastic stiffness. The constitutive relations for elastoplastic responses are decoupled from the degradation damage response, which provides advantages in the numerical implementation. In the present model, the strength function for the effective stress is used to control the evolution of the yield surface, so that calibration with experimental results is convenient. A simple and thermodynamically consistent scalar degradation model is introduced to simulate the effect of damage on elastic stiffness and its recovery during crack opening and closing. The performance of the plastic-damage model is demonstrated with several numerical examples of simulating monotonically and cyclically loaded concrete specimens.

Updating Models and Their Uncertainties. I: Bayesian Statistical Framework

Abstract: The problem of updating a structural model and its associated uncertainties by utilizing dynamic response data is addressed using a Bayesian statistical framework that can handle the inherent ill-conditioning and possible nonuniqueness in model updating applications. The objective is not only to give more accurate response predictions for prescribed dynamic loadings but also to provide a quantitative assessment of this accuracy. In the methodology presented, the updated (optimal) models within a chosen class of structural models are the most probable based on the structural data if all the models are equally plausible a priori. The prediction accuracy of the optimal structural models is given by also updating probability models for the prediction error. The precision of the parameter estimates of the optimal structural models, as well as the precision of the optimal prediction-error parameters, can be examined. A large-sample asymptotic expression is given for the updated predictive probability distribution of the uncertain structural response, which is a weighted average of the prediction probability distributions for each optimal model. This predictive distribution can be used to make model predictions despite possible nonuniqueness in the optimal models.

Rolling Resistance at Contacts in Simulation of Shear Band Development by DEM

Abstract: To simulate numerically the microstructure of shear bands, the distinct element method was modified such that the effect of rolling resistance at contacts could be taken into account. To this end, the relative movement by rolling is related to the relative rotation between two particles with a common contact, which makes it possible to generalize the conservation law of angular momentum for a more general case than the moments can be transmitted through contacts. Not only the generation of large voids inside a shear band but also the high gradient of particle rotation along the shear band boundaries can be reproduced, in a manner quite similar to those of natural granular soils, when the rolling resistance at contacts is considered. The development of columns is a common feature that appears in the strain hardening process, and buckling of the columns parallels the development of shear bands. The generation of large voids and the high gradient of particle rotation are produced as a result of the buckling of the columns.

Updating models and their uncertainties. ii: model identifiability

Abstract: The problem of model identifiability is addressed. The goal is to find all the structural models within a specified class that produce the same output at a set of observed degrees of freedom as a given model in the class when they are all subjected to the same input. A new algorithm is presented to solve this problem for a class of multi-degree-of-freedom linear structural models, and the approach is illustrated with examples.

Simulation of stationary non-Gaussian translation processes

Abstract: A simulation algorithm is developed for generating realizations of non-Gaussian stationary translation processes \iX(\it) with a specified marginal distribution and covariance function. Translation processes are memoryless nonlinear transformations \IX(t)=g[Y(t)]\N of stationary Gaussian processes \iY(\it). The proposed simulation algorithm has three steps. First, the memoryless nonlinear transformation \ig and the covariance function of \iY(\it) need to be determined from the condition that the marginal distribution and the covariance functions of \iX(\it) need to be determined from the condition that the marginal distribution and the covariance functions of \iX(\it) coincide with specified target functions. It is shown that there is a transformation \ig giving the target marginal distribution for \iX(\it). However, it is not always possible to find a covariance function of \iY(\it) yielding the target covariance function for \iX(\it). Second, realizations of \iY(\it) have to be generated. Any algorithm for generating samples of Gaussian processes can be used to produce samples of \iY(\it). Third, samples of \iX(\it) can be obtained from samples of \iY(\it) and the mapping of \iX(\it)=\ig[\iY(\it)]. The proposed simulation algorithm is demonstrated by several examples, including the case of non-Gaussian translation random field.

Mechanics of bond and interface shear transfer in optical fiber sensors

Abstract: Optical fiber sensors are emerging as a superior nondestructive means for condition evaluation of civil structures. The ability of an optical fiber sensor to monitor strain distribution in a structural material depends on the bonding characteristics between the material and the optical fiber. The strain field transferred from the structure to the optical fiber sensor generates changes in the characteristics of the light signal transmitted by the glass core of the optical fiber. Transduction of this signal will provide a means for measurement of strain. However, the mechanical properties of the protective coatings employed in conjunction with optical fibers alter the strain transduction capabilities of the sensor. A portion of the strain is absorbed by the protective coating of the optical fiber, and hence, only a segment of structural strain is sensed. In the study reported here, a model is introduced and tested through which it is possible to interpret the actual level of structural strains from the values measured by an optical fiber sensor. A number of realistic assumptions were introduced to simplify the development of the mathematical rigor. It was determined that the strain transfer characteristics of optical fibers depend on the mechanical properties of the glass core, the protective coating, and the gauge length of the optical fiber. Mathematical expressions are developed through which it is possible to describe the level of strain loss within the protective coating, and the amount transferred to the optical fiber core. The theoretical findings were verified through a series of experiments involving white light interferometry. The investigation encompassed repeated experiments with a range of fiber sensor gauge lengths. The experimental program included evaluation of strain transfer capabilities of coated as well as bare fibers.

Application of Wavelet Theory for Crack Identification in Structures

Abstract: This paper presents the first attempt of an application of the wavelet theory for the crack identification of structures. As a case study, we consider the crack identification using the wavelet theory for a simply supported beam with a transverse on-edge nonpropagating open crack. A mathematical model of the cracked beam is derived and the wavelet expressions in the space domain are proposed for solution. For comparison purposes, the simply supported cracked beam is solved using both the eigentheory and the wavelet method of analysis. The results show that crack identification via wavelet analysis is accomplished easily whereas it can hardly be detected by the traditional eigenvalue analysis.

Viscoelastic Continuum Damage Model of Asphalt Concrete with Healing

Abstract: A viscoelastic constitutive model of asphalt mixtures that accounts for the rate-dependent damage growth and microdamage healing is presented in this paper. An elastic continuum damage model, which is based on thermodynamics of irreversible processes with internal state variables, is first reviewed and extended to a corresponding viscoelastic model using an elastic-viscoelastic correspondence principle. A rate-type internal state evolution law is employed to describe the damage growth and microdamage healing in asphalt concrete. An analytical representation of the model is established for the uniaxial loading condition. Tensile uniaxial cyclic tests were performed under the controlled-strain mode with different strain amplitudes to determine model parameters. The resulting constitutive model successfully predicts the damage growth and recovery in asphalt concrete under multilevels of loading, varying rates of loading, different modes of loading (controlled-strain and controlled-stress), and random rest periods.

Viscoelastic constitutive model for asphalt concrete under cyclic loading

Abstract: This paper presents a mechanistic approach to uniaxial viscoelastic constitutive modeling of asphalt concrete that accounts for damage evolution under cyclic loading conditions. Schapery's elastic-viscoelastic correspondence principle is applied as a means of separately evaluating viscoelasticity and time-dependent damage growth in asphalt concrete. The time-dependent damage growth in asphalt concrete is modeled by using a damage parameter based on a generalization of microcrack growth law. Internal state variable formulation was used in developing the analytical representation of the model. Tensile uniaxial fatigue tests were performed under the controlled-strain mode to determine model parameters. Then, the resulting constitutive equation was used to predict the stress-strain behavior of the same materials under controlled-stress mode. The constitutive equation proposed in this paper satisfactorily predicts the constitutive behavior of asphalt concrete all the way up to failure under various loading conditions including different stress-strain amplitudes, monotonic versus cyclic loadings, and different modes of loading.

Shrinkage Cracking of Restrained Concrete Slabs

Abstract: The goal of this investigation was to better understand and predict early-age shrinkage cracking in restrained concrete structures. The threefold aim of this study included: (1) the development of test methods to assess the potential for shrinkage cracking; (2) the development of a theoretical model to predict cracking; and (3) the evaluation of a nonexpansive shrinkage reducing admixture. Two tests configurations were used in evaluating the potential for restrained shrinkage cracking, ring-type and slab-type specimens. Experiments were performed on both normal and high strength concrete with 0, 1, and 2% shrinking reduction admixture. Time-dependent material properties were measured and the effect of restraint was tested in both ring and slab specimens. A computer-automated fracture mechanics model was used to successfully predict the age at first cracking. Results exhibit favorable comparison between theoretical modeling and experimental observations.

Rotating crack model with transition to scalar damage

Abstract: Traditional smeared-crack models for concrete fracture are known to suffer by stress locking (meaning here spurious stress transfer across widely opening cracks), mesh-induced directional bias, and possible instability at late stages of the loading process. The present paper suggests to overcome these deficiencies by combining the standard rotating crack model with the scalar damage concept. The combined model keeps the anisotropic character of the rotating crack but it does not transfer spurious stresses across widely open cracks. This is documented by examples including the three-point bending, wedge splitting, and four-point shear single-edge-notched specimens. The model is then extended to a nonlocal formulation, which not only acts as an efficient localization limiter but also alleviates mesh-induced directional bias. Transition to damage can prevent a special type of material instability arising due to negative shear stiffness of the rotating crack model.

Smart Prestressing with Shape-Memory Alloy

Abstract: Shape-memory effect in nickel-titanium (nitinol) alloy was successfully utilized as a way of inducing additional prestressing in concrete. Strands made with NiTi (nickel/titanium) shape-memory alloy (SMA) wires were elongated beyond their plastic limit and subsequently were embedded in model concrete (mortar) beams. Upon electrical heating, a martensite-to-austenite phase transformation takes place and the material undergoes large shrinkage strains. This strain energy can be used to generate a significant prestressing force in concrete. Potentially, this provides a means of creating a “smart bridge,” where the amount of prestress can be increased or decreased as needed. Such a structure could actively accommodate additional loading, or remedy prestress losses over time. Properties of the SMA material and the micromechanics of its bond with concrete were investigated. Strands made with SMA wires were electrically actuated to induce deflection and failure in concrete (mortar) beams. Optical microscopy and t...

Analysis of rotating crack model

Abstract: This paper extends the standard rotating crack (RC) model to a formulation with multiple orthogonal cracks. The corresponding stress evaluation algorithm is described, and a derivation of the tangent stiffness matrix is presented. The derivation is extended to the case of equal principal strains, in which the classical formula for the tangent shear modulus fails. A condition excluding snapback of the stress-strain diagram for an arbitrary loading path is derived. Attention then shifts to stress locking, meaning here spurious stress transfer across widely opening cracks. The problem is illustrated by numerical examples. The mechanism of stress transfer is thoroughly analyzed, and the source of locking is detected. A remedy and extension of the model to a nonlocal formulation is described in a separate paper.

Behavior and strength of laminated glass

Abstract: Published experimental data indicate that under most conditions laminated glass strength equals or exceeds the strength of monolithic glass of the same nominal thickness. To date, these experimental data exist without a theoretical model. This paper presents a theoretical, engineering mechanics model that accounts for factors that affect laminated glass behavior including temperature, thickness of the interlayer, and composition of the interlayer. It presents additional fracture strength data for laminated glass lites with a thicker interlayer than in previous tests. Both the theoretical model and the new fracture strength data indicate that laminated glass strength increases as interlayer thickness increases and that laminated glass strength decreases as temperature increases. Although an increase in temperature beyond 38°C (100°F) leads to a decrease in laminated glass strength, the theoretical model indicates that laminated glass possesses significantly more strength than “layered glass,” e.g., simply two plies of glass with no shear transfer, at temperatures above 49°C (120°F).

Investigation of Tuned Liquid Dampers under Large Amplitude Excitation

Abstract: The behavior of tuned liquid dampers (TLD) was investigated through laboratory experiments and numerical modeling. Large amplitude excitation is the primary focus, as previous research was limited to small amplitude motion. Time histories of the base shear force and water-surface variations were measured by precisely controlled shaking table tests. The results are compared with a numerical model. The random-choice numerical method was used to solve the fully nonlinear shallow-water wave equations. The results suggest that the model captures the underlying physical phenomenon adequately, including wave breaking, for most of the frequency range of interest and over a wide range of amplitude excitation. It was found that the response frequency of tuned liquid dampers increases as excitation amplitude increases, and the TLD behaves as a hardening spring system. To achieve the most robust system, the design frequency for the damper, if it is computed by the linearized water-wave theory, should be set at the value lower than that of the structure response frequency; hence, the actual nonlinear frequency of the damper matches the structural response. It was found that, even if the damper frequency had been mistuned slightly, the TLD always performed favorably; we observed no adverse effect in the wide range of experimental parameters tested in this study.

Adaptive H^∞ filter: Its application to structural identification

Abstract: By adding the function of memory fading for past observation data to the \iH\d∞ filter, the adaptive \iH\d∞ filter was developed for identifying structural systems with nonstationary dynamic characteristics. Identification algorithms are proposed for time-varying structural systems in which the velocity and displacement of each floor are available for observation, as well as for the case when only the velocity and displacement of some floors are available. The Akaike-Bayes information criterion is used to determine the optimal forgetting factor. Identification algorithms that use the adaptive \iH\d∞ and Kalman filters are applied to a five-degree of freedom (DOF) linear system with nonstationary dynamic characteristics and to a five-DOF nonlinear structural system. Digital simulation results show that the adaptive \iH\d∞ filter efficiently traces the time-varying properties of structural systems. The behavior of the adaptive \iH\d∞ filter is better than that of the adaptive Kalman filter for identifying a structural system with time-varying dynamic characteristics. The former is more efficient and robust for identifying structural systems with nonstationary dynamic characteristics.

Nonlinear structural control using neural networks

Abstract: Recently, Ghaboussi and Joghataie presented a structural control method using neural networks, in which a neurocontroller was developed and applied for linear structural control when the response of the structure remained within the linearly elastic range. One of the advantages of the neural networks is that they can learn nonlinear as well as linear control tasks. In this paper, we study the application of the previously developed neurocontrol method in nonlinear structural control problems. First, we study the capabilities of the linearly trained neurocontrollers in nonlinear structural control. Next, we train a neurocontroller on the nonlinear data and study its capabilities. These studies are done through numerical simulations, on models of a three-story steel frame structure. The control is implemented through an actuator and tendon system in the first floor. The sensor is assumed to be a single accelerometer on the first floor. The acceleration of the first floor as well as the ground acceleration are used as feedback. In the numerical simulations we have considered the actuator dynamics and used a coupled model of the actuator-structure system. A realistic sampling period and an inherent time delay in the control loop have been used.

Experimental Study of Drained Creep Behavior of Sand

Abstract: The experimental techniques pertaining to accurate measurement of creep in sand are explained in detail. Triaxial compression and proportional loading tests were performed in a triaxial setup for which special procedures were developed to maintain constant temperature, constant confining pressure, and constant axial load, whereas the axial and volumetric deformations were measured using two types of mechanical measurement systems, both free of zero drift. Special attention was paid to the avoidance of air and water leakage through the membrane in the long-term tests. The experiments show that the nature of creep strains is similar to that of plastic strains. They may be predicted from the framework provided by the hardening plasticity theory. In particular, the potential surface determined for the prediction of plastic strains may also be used for the prediction of time-dependent creep strains. From the experiments it also appears that the yield surface and the plastic potential surface move out together, and the point at which to evaluate inelastic strain increment directions is at the current location of the yield surface and the accompanying plastic potential surface.

Constitutive modeling of unsaturated drying deformable materials

Abstract: Thermodynamics of open continua, when applied directly at the macroscopic engineering scale, allows one to extend unambiguously the principal concepts of continuum thermomechanics of solids to polyphasic porous materials, whose fluid constituents are subject to liquid-vapor phase change. This approach provides a consistent and relevant framework for the formulation of the constitutive equations of partially saturated deformable porous materials such as concrete. After recalling the general theory, the modeling is specified for porous materials that are partially saturated by a liquid water phase changing into its vapor phase, the latter forming with the dry air an ideal mixture. The nonlinear poroelasticity, as reference modeling, is then detailed. The theory is applied to the modeling of the drying shrinkage of concrete samples with isothermal sorption curves as only experimental data. The predicted shrinkage is found to be in close agreement with the observed one for a range of humidity greater then 50%. The drying shrinkage of a wall is finally examined. The analysis includes the study of the temperature variations due to latent heat effects. These variations are shown to be negligible.

Experimental determination of frequencies and tension for elastic cables

Abstract: The results of experiments for the natural frequencies and tension of a cable corresponding to a scale model of a guy wire for a 411 m (1,350 ft) tall radio navigation tower are compared to the theoretical predictions. For the theoretical determination of natural frequencies, alternate methods of using curvature are presented. The first 10 natural frequencies of the cable were measured at a number of different wire tension levels and were found to differ from the theoretical values by an average of only 0.7%. The experimental results for the frequencies show clear evidence of avoided crossings. The tension at the base of the cable was determined with an accuracy of 3% by comparing the measured natural frequencies with the theoretical predictions.

Seismic response of sdof systems by wavelet modeling of nonstationary processes

Abstract: A wavelet-based random vibration theory is presented in this paper to predict the stochastic seismic response of a single-degree-of-freedom system. Functions of wavelet coefficients are used to model ground motions as nonstationary processes in terms of both amplitude and frequency nonstationarity. An orthogonal basis function has been proposed for this purpose. An input-output relationship is developed and closed form solutions are obtained for the output instantaneous power spectral density function and its moments. These moments are used to predict the response statistics of interest. The largest peak amplitude is predicted based on the existing first passage formulation, whereas the higher order peak amplitudes are estimated by using the order statistics approach for an “equivalent” stationary process. The proposed formulation has been validated through statistical simulation in the cases of two example motions and several single-degree-of-freedom oscillators.

Dynamics of rigid block due to horizontal ground motion

Abstract: This paper addresses the problem of a rigid block above the foundation subjected to a horizontal ground motion The objective of this work is to formulate criteria that separate the sticked and the slipped modes of the motion by an analytical approach The influence of the three parametric quantities: (1) μ\ds (static friction coefficient); (2) \ib/\ih (relative width); and (3) \ia/\ig (\ia is the acceleration of the base and \ig is the gravitational acceleration) upon the motion mode nature is investigated It is shown that disregard of the sliding can involve mistakes in the study of the body rotation

Structural Damage Detection from Incomplete and Noisy Modal Test Data

Abstract: Existing research on structural damage detection usually requires information at every degree of freedom, and this contradicts the usual practice of having a small number of sensors employed over limited locations on the structure. A method to detect the location and to estimate the magnitude of damage in a structure down to the element level with incomplete and noisy measured modal data is proposed. The method consists of three stages: expansion of the measured mode shapes, localization of the damage domain using the elemental energy quotient difference, and damage quantification based on sensitivity of the modal frequency. A new mode shape expansion method is presented, and the effectiveness of the combined use of this method and the elemental energy quotient difference is demonstrated with incomplete measurement. The treatment of modeling errors is discussed. A criterion for selection of the damaged members is proposed and practical means to improve the identification results are presented. Several damage cases of the European Space Agency structure and of a single-bay two-story portal steel frame structure in the laboratory are investigated. The practical problem of having random error and systematic error in the measurement is studied. Results show that the proposed three-stage approach can effectively locate and quantify damages in a real structure.

Analysis and experiments on stress waves in planar trusses

Abstract: The dynamics of planar trusses are investigated in terms of axial (longitudinal) stress waves, which propagate along structural members and scatter at the joints. The scattering coefficients representing the reflection and transmission of axial waves at each joint are derived from the dynamics and compatibility conditions of the joint. The complex multiple reflections of waves within the structure are evaluated in the frequency domain with a newly developed reverberation matrix, which is formulated from the scattering coefficients and propagating phase factors. Transient waves are then derived by Fourier synthesis, and evaluated by a Fast Fourier Transform algorithm. Experimental results of propagating broad band pulses are presented for a truss model excited by a step loading. Comparison between theoretical results and transient wave records indicate that the axial wave theory is valid only for the response at the very early time. The discrepancy is much reduced if the scattering coefficients are modifie...

Dynamics of Seismic Pounding at Expansion Joints of Concrete Bridges

Abstract: Motivated by a need to understand the effects of earthquake-induced pounding at thermal expansion joints of concrete bridges, the first part of this paper deals with collinear impact between concrete rods of the same cross section but different lengths. It is shown that (1) the coefficient of restitution between rods depends only on the length ratio and the damping ratio of the rod material and (2) the duration of impact is equal to the fundamental period of axial vibration of the shorter rod. These results are used in the second part of this paper to formulate a realistic yet simple analysis of seismic pounding in concrete bridges. In determining a suitable value of the coefficient of restitution, use is made of the strong-motion data recorded on a concrete bridge that experienced significant pounding during recent California earthquakes. It is shown that (1) seismic pounding generally reduces the column forces; (2) large impact forces generated in the superstructure are not transmitted to the bridge columns and foundations; and (3) pounding does not increase the longitudinal separation at the hinges.

Aerodynamic control of bridge deck flutter by active surfaces

Abstract: An active aerodynamic control method of suppressing flutter of a very-long-span bridge is presented in this paper. The control system consists of additional control surfaces attached to the bridge deck; their torsional movement, commanded via feedback control law, is used to generate stabilizing aerodynamic forces. The frequency independent formulation of unsteady aerodynamic forces acting on the bridge deck as well as the control surfaces is derived through rational function approximation. The high precision of approximation is ensured by multilevel linear and nonlinear constrained optimization. Although the proposed mathematical model of aeroservoelastic system is augmented by new aerodynamic states, it is in the form of a set of constant coefficient differential equations that are particularly convenient for control law synthesis. The obtained equations of motion are functions of mean wind speed so the efficiency of application of the conventional constant gain optimal feedback control is limited. To cope with the system dependence on wind speed, a variable-gain control is proposed. The static output variable-gain approach is formulated in terms of a mathematical optimization problem and the necessary conditions are derived. Application of the variable-gain control provides variation of control strategies in different wind velocities and is found to be efficient for the studied aerodynamic active control of bridge deck flutter.

One-Sided Stress Wave Velocity Measurement in Concrete

Abstract: Measurement of the velocity of stress waves in concrete provides valuable information on the state of the material. Recently, a number of papers have been published on wave velocity measurements in concrete when access to only one surface of the structure is possible, such as for the case of concrete pavements. In this paper, the existing one-sided methods for stress wave measurement in concrete are reviewed. Then, a modified method for one-sided stress wave velocity determination in concrete is introduced; the novel aspect of the modified technique is the data collection and processing system, which more accurately determines the arrival of the generated longitudinal and surface waves. The modified method, which is demonstrated on a variety of materials including steel, PMMA, and concretes of varying composition, is shown to be superior to existing one-sided techniques. Using the developed technique, the significant effect of the moisture content gradient within concrete on one-sided velocity measurements is demonstrated. Finally, one-sided velocity measurements are shown to be useful for monitoring the strength gain of early age concrete.

Moving loads on a plate on elastic foundation

Abstract: A number of studies have been conducted recently to find the dynamic response of multilayered media as models of pavement systems to moving loads. The dynamic response of an infinite plate on an elastic foundation subjected to constant amplitude or harmonic moving loads was investigated. The advance velocity was assumed to be constant. Formulations were developed in the transformed field domain using a double Fourier transform in space and moving space for moving constant loads; a triple Fourier transform in time, space, and moving space to include the initial application of the load for moving harmonic loads; and a double Fourier transform in space and moving space for the steady-state response to moving harmonic loads. The effects of velocity, load frequency, and damping on the deflected shape, and the maximum displacement were investigated. The critical (resonant) velocities and frequencies were obtained by analyses, and expressions to find them were suggested. The effect of multiple loads on the maximum displacement was also investigated. The variation of the maximum dynamic displacement was affected by the distances and the differences in phase between the loads.

Applications of FEM on Free and Forced Vibration of Laminated Shells

Abstract: In this paper, the finite element method has been applied to solve free and forced vibration problems of isotropic and laminated composite shells with and without cutouts employing the eight-node isoparametric finite element formulation. Specific numerical problems of earlier investigators are solved to compare their results. Moreover, free vibration problems of cylindrical, spherical, saddle (hyperbolic paraboloid bounded by parabolas), hypar (hyperbolic paraboloid bounded by straight lines), and conoidal shells with cutouts and forced vibration of composite hypar and conoidal shells without cutouts are examined to arrive at some conclusions useful to the designers. Eccentrically positioned cutouts and transient stresses are other aspects studied in detail in free and forced vibration analyses, respectively.

Mechanical Behavior of Concrete under Physical-Chemical Attacks

Abstract: The analysis of the evolution of stress-strain states into reinforced concrete structures due to humidity and temperature changes and physical-chemical attacks by pollutant species is presented. Humidity and temperature affect both the process of cement hydration and the progress of shrinkage and creep, while thermal transients cause spatial variable thermal deformations. Moreover, aggressive species, which penetrate from the external environment into concrete via diffusive processes, might lead both to the reinforcement corrosion (i.e., carbonation phenomena and chlorides) and to the concrete damage producing expansive phenomena (i.e., sulfates and calcium chloride). Within the framework of a finite-element approach, the solution of the mechanical equilibrium of the elastic-damage continua, coupled with the diffusion processes of humidity, temperature, and chemical species, is carried out. Some examples are shown in order to demonstrate the reliability of the proposed approach in practical engineering pr...