Search

De-bonding of carbon fiber reinforced polymers (CFRP) sheets and plates from the concrete substrate is one of the major reasons behind premature failures of beams that are externally strengthened with such CFRP materials. To delay or prevent de-bonding and therefore enhancing the load carrying capacity of strengthened beams, several anchorage systems were developed and used. This paper investigates the use of CFRP mechanical anchorage of CFRP sheets and plates used to externally strengthen reinforced concrete beams under flexure. The pin-and-fan shape CFRP anchor, which is custom-made from typical rolled fiber sheets and bundles of loose fiber is used. Several reinforced concrete beams were casted and tested in standard four-point bending scheme to study the effectiveness of this anchorage system. The beams were externally strengthened in flexure with bonded CFRP sheets and plates and then fastened to the soffit of the beams’ using various patterns of CFRP anchors. It is observed that the CFRP plates begins to separate from the beams as soon as de-bonding occurs in specimens without CFRP anchors, while in beams with CFRP anchors de-bonding was delayed leading to increase in the load carrying capacity over the un-anchored strengthened beams.

This study presents the bending performance of reinforced concrete (RC) beams strengthened with hybrid carbon and basalt fiber reinforced polymer (CFRP/BFRP) composite sheets. The proposed hybrid system is intended to improve the properties of the strengthening composite material, in which high strength CFRP sheets are combined with ductile BFRP sheets via epoxy adhesive. A total of 10 beams were tested, nine of which were strengthened with different combinations of CFRP and BFRP sheets, and the remaining beam was unstrengthened to serve as a control specimen. The test results indicated clear improvements in the load-carrying capacity and ductility of the strengthened specimens. The range of increase in the ultimate capacity of the hybrid-strengthened beams over that of the control beam specimen was between 66 and 75%. In addition, the deflection ductility indices of the hybrid beams presented an improvement up to 108% compared to those strengthened with CFRP laminates only. Finite element (FE) models were also developed to predict the response and load-carrying capacity of the tested specimens. The models precisely predicted the experimentally obtained load-carrying capacity and associated mid-span deflections at yield and ultimate loads, with a deviation that did not exceed 12%.

Fiber-reinforced polymer (FRP) composites continue to provide designers with the ability to deliver innovative and intelligent solutions to overcome the ever-growing aging issues in infrastructure. Since it has been more than 50 years to the introduction of FRP materials to the construction industry, this paper presents a state-of-the-art review on historic and recent developments of FRP in strengthening and rehabilitation of civil engineering applications. This review highlights some of the classic and modern experimental, numerical, and analytical studies associated with the integration of FRPs into buildings, among other structures. The discussion presented herein aims at covering application of FRP systems in reinforced concrete structural members and also highlights the performance of FRPs (including bonding agents) under extreme conditions such as elevated temperature, saline environment, and cycles of freezing and thawing. This paper also presents a collective perspective on number of limitations, challenges and research needs associated with successful, sustainable, and durable implementation of FRPs in civil infrastructure.

The fatigue life of steel reinforcing bars depends on the energy dissipated during cyclic loading. Steel bars play a major role in energy dissipation in reinforced concrete structures under low-cycle fatigue loading during earthquakes. In this study, seven artificial neural network (ANN) models were developed to predict the fatigue life of steel bars based on energy dissipated in the first cycle (W1), average cycles (WA), and total energy dissipated in all cycles (WT). The ANN-predicted number of reversals to fatigue failure (2Nf) were comparable to the experimentally measured values and also to the values predicted using nonlinear regression (NLR) models. The best overall ANN result was obtained when W1, WA, and WT were used together as input for the ANN with correlation coefficient r=0.985, normalized mean square error (NMSE)=0.0517, and mean absolute percent error (MAPE)=10.8%. When WA was used as a single input, the predicted 2Nf are also relatively accurate. In conclusion, the developed ANN m...

Fiber Reinforced Polymer (FRP) materials have been recently used as novel materials to retrofit aging and deficient structures. Several research programs have succeeded in narrowing down the knowledge gap of the debonding mechanism associated with the failure of externally bonded FRP systems. This study seeks numerical investigation of plate debonding and performance of reinforced concrete (RC) beams externally strengthened with bonded Carbon Fiber Reinforced Polymers (CFRPs) plates running for a length covering 25% of the shear span. The results are compared with plates covering 85% of the shear span in addition to a control unstrengthened specimen. The aim of this paper is to develop 3D finite element (FE) models that can accurately simulate the response and performance of RC beams externally strengthened with short-length CFRP plates. A total of six beams were modeled and the load–midspan deflection results and failure modes were compared with experimentally measured data published in the literature. Two out of the five strengthened beams were bonded to the soffit of the beams without any means of end anchorages. The other three beams were strengthened with CFRP plates and anchored transversely at the plate’s ends with different arrangements of CFRP U-wrap sheets. The developed models incorporate the different material nonlinear constitutive laws including the bond-slip action between steel rebars and surrounding concrete and debonding at the CFRP–concrete interface. The predicted and measured load–midspan deflection response results in addition to the failure modes are compared. It was observed that the predicted FE results are in good agreement with the experimental measured test data. A parametric study was then performed using the validated FE model to investigate the effect of the flexural reinforcement bar diameter as well as arrangements of the CFRP U-wraps. It has been concluded that the developed FE models are capable of accurately predicting and capturing capacity the debonding failure mode of RC beams strengthened with FRP plates.

In this paper, a set of simplified design equations for an unbonded posttensioned (PT) precast split hybrid shear wall system is developed. Such a system was proposed by the Precast Seismic Structural Systems (PRESSS) and can be used as a bearing wall or a special reinforced concrete wall for building frames, as defined in ASCE/SEI 7, for eliminating residual drift after seismic events. The panels are anchored to the foundation with unbonded PT tendons located at the panel center; adjacent panels are connected with uniformly distributed energy dissipating coupling devices. An iterative design procedure to calculate the required area of the PT reinforcement and the total yield force of all shear connectors in one vertical joint was proposed by PRESSS. This iterative procedure is exact, but tedious and lengthy. A simpler nondimensional chart-based design procedure was proposed by the writers. This procedure is efficient, but has limitations. A noniterative procedure adopted by ACI ITG-5.2, although ...

This paper presents a finite element (FE) model for predicting the nonlinear response and behavior of a reinforced concrete T-beam deficient in shear under cyclic loading. Cracking loads, failure loads, response hysteresis envelopes and crack patterns were used as bench mark for comparison between experimental and FE results. A parametric study was carried out to predict the optimum combination of the open and close crack shear transfer coefficients (beta(i) and beta(c)) of the constitutive material model for concrete. It is concluded that when both shear transfer coefficients are equal to 0.2 the FE results gave the best correlation with the experimental results. The results were also verified on a rectangular shear deficient beam (R-beam) tested under cyclic loading and it is concluded that the variation of section geometry has no effect on the optimum choice of the values of shear transfer coefficients of 0.2. in addition, a parametric study based on the variation of concrete compressive strength, was carried out on the T-beam and it is observed that the variation of concrete compressive strength has little effect on the deflection. Further conclusions and observations were also drawn.

This paper experimentally investigated the buckling capacity of built-up steel columns mainly, Cruciform Columns (CC) and Side-to-Side (SS) columns fabricated from two Universal Beam (UB) sections. A series of nine experimental tests comprised of three UB sections, three CC sections and three SS sections with different lengths were tested to failure to measure the ultimate axial capacity of each column section. The lengths used for each category of columns were 1.8, 2.0, and 2.2 m with slenderness ratios ranging from 39-105. The measured buckling loads of the tested specimens were compared with the predicted ultimate axial capacity using Eurocode 3, AISC LRFD, and BS 5959-1. It was observed that the failure modes of the specimens included flexural buckling, local buckling and flexural-torsional buckling. The results showed that the ultimate axial capacity of the tested cruciform and side-by-side columns were higher than the code predicted design values by up to 20%, with AISC LRFD design values being the least conservative and the Eurocode 3 design values being the most conservative. This study has concluded that cruciform column and side-to-side welded flange columns using universal beam sections are efficient built-up sections that have larger ultimate axial load capacity, larger stiffness with saving in the weight of steel used compared to its equivalent universal beam counterpart.

The increase in issue width and instructions window size in modern processors demand an increase in the size of the register files, as well as an increase in the number of ports. Bigger register files implies an increase in power consumed by these units as well as longer access delays. Models that assist in estimating the size of the register file, and its timing early in the design cycle are critical to the time-budget allocated to a processor design and to its performance. In this work, we discuss a Radial Base Function (RBF) Artificial Neural Network (ANN) model for the prediction of time and area for standard cell register files designed using optimized Synopsys Design Ware components and an UMC130 nm library. The ANN model predictions were compared against experimental results (obtained using detailed simulation) and a nonlinear regression-based model, and it is observed that the ANN model is very accurate and outperformed the non-linear model in several statistical parameters. Using the trained ANN model, a parametric study was carried out to study the effect of the number of words in the file (D), the number of bit in one word (W) and the total number of read and write ports (P) on the latency and area of standard cell register files.

The aim of this experimental investigation is to study the effect of the ratio of carbon fiber-reinforced polymer (CFRP) precured laminate length to shear span and different end plate anchorage systems on the flexural behavior of reinforced concrete (RC) beams cast with self-consolidating concrete (SCC). SCC with a grade of 54 MPa has been used throughout this research to ensure consistent high quality and high concrete compressive strength in all beams and to eliminate the need of any compaction. Ten RC beams strengthened with CFRP plate lengths to shear span ratio of 0, 25, 70, and 85% with and without end anchorages, were tested under monotonic loading. In particular, a single layer of U-wrap sheet and two layers of U-wrap sheets with one layer in the longitudinal direction and the other in the transverse direction were used as end anchorages (double wrap). The results were compared with each other and with those of the same test conducted on an unstrengthened control beam specimen. The load-deflection...

This study presents a model for predicting the low-cycle fatigue life of steel reinforcing bars using Artificial Neural Network (ANN). A Radial Basis Function (RBF) artificial neural network topology with two additional hidden layers and four neurons (processing elements) in each of these layers is used. The input parameters for the network are the maximum tensile strain (es,max) and the strain ratio (R) and the output of the ANN is the number of cycles to fatigue failure (Nf). Low-cycle fatigue tests were conducted by the authors in a previous study for different types of steel reinforcing bars subjected to different strain amplitudes and at different strain ratios. The data resulted from these tests were used to train and test the ANN. It is observed that the ANN prediction of low-cycle fatigue life of steel reinforcing bars is within ±2 cycles of the experimental results for the majority of the test data. A parametric study had been carried out to investigate the effect of maximum strain and strain ratio on the fatigue life of steel reinforcing bars. It is concluded that both the strain ratio and the maximum strain have significant effect on the low-cycle fatigue life of such bars, especially at low values of maximum strain and their effect should be considered in both analysis and design. Other observations and conclusions were also drawn.

The use of Carbon Fiber Reinforced Polymers (CFRP) to strengthen reinforced concrete beams under bending and shear has gained rapid growth in recent years. The performance of shear strengthened beams with externally bonded CFRP laminate or fabric strips is raising many concerns when the beam is loaded under cyclic loading. Such concerns warrant experimental, analytical and numerical investigation of such beams under cyclic loading. To date, limited investigations have been carried out to address this concern. This paper presents a numerical investigation by developing a nonlinear finite element (FE) model to study the response of a cantilever reinforced concrete T-beam strengthened in shear with side bonded CFRP fabric strips and subjected to cyclic loading. A detailed 3D nonlinear finite element model that takes into account the orthotropic nature of the polymer's fibers is developed. In order to simulate the bond between the CFRP sheets and concrete, a layer having the material properties of the adhesive epoxy resin is introduced in the model as an interface between the CFRP sheets and concrete surface. Appropriate numerical modeling strategies were used and the response envelope and the load-displacement hysteresis loops of the FE model were compared with the experimental response at all stages of the cyclic loading. It is observed that the responses of the FE beam model are in good agreement with those of the experimental test. A parametric study was conducted using the validated FE model to investigate the effect of spacing between CFRP sheets, number of CFRP layers, and fiber orientation on the overall performance of the T-beam. It is concluded that successful FE modeling provides a practical and economical tool to investigate the behavior of such strengthened beams when subjected to cyclic loading.

The applications of Carbon Fiber Reinforced Polymers (CFRP) in construction have been grown drastically in the last 20 years because of the wide range of advantages and benefits of using CFRP in buildings, bridges and other type of structures. Nowadays, it is used for retrofitting concrete, masonry, steel and timber structures to resist both static and dynamic loads. Since the cost of replacing an existing structure is far more expensive than using FRP materials to strengthen it, CFRP strengthening techniques seem to be cost effective and easy to implement. Numerous experimental and numerical studies have been conducted to investigate the flexural and shear performance of uncracked reinforced concrete (RC) members externally strengthened with CFRP laminates or strips. However, the most practical usage of CFRP is to retrofit sections that had already been cracked and in need of maintenance. The fact that there have been limited studies to investigate the behavior and performance of pre-cracked beams strengthened with CFRP systems necessitated new and further investigations. In this study, the flexural performance of cracked RC beams retrofitted with CFRP plates and epoxy injections are investigated. The results of the cracked beams are compared with two control beams, a virgin un-strengthened beam and an uncracked beam strengthened with a CFRP plate covering 90% of the beam’s span. Load-midspan deflections for these beams were generated and compared. It is observed that the retrofitted cracked beams displayed more strength than the control beam. The results presented herein can aid designers in establishing a better understanding of the flexural performance of pre-cracked beams and how to economically retrofit such structural members.

Seismic retrofitting of reinforced concrete (RC) beams by means of carbon fiber reinforced polymer (CFRP) composites is one of the state-of-the-art techniques that have been widely practiced lately. Such external strengthening schemes seem to enhance both stiffness and strength of RC beams when subjected to static and cyclic loading. Extensive research investigation has been carried out for beams subjected to monotonic static loading while limited research data is available for beams subjected to cyclic loadings. Therefore, this study is initiated and its aim is to present the results of full scale experimental testing of RC beams under four-point-bending loading and subjected to monotonic and cyclic loading histories up to failure of the specimens. An unstrengthened RC beam was tested monotonically to serve as a bench-mark. The remaining two externally strengthened RC beams with different anchorage schemes were tested under cyclic loading. The strengthening test matrix included beams bonded with a unidirectional CFRP plate that covers 90% of the beam's soffit length, with one or two unidirectional layers of CFRP wraps at anchorage locations along the beam's length. The anchorage locations were at the edges of the CFRP plate and at the middle of the beam's span. The results presented herein show an increase in the overall strength for the strengthened beams over the unstrengthened ones. The different failure modes and the resulting ductility of the tested specimens are also discussed. This study is considered to be the first part of an extensive program that aims to investigate the different parameters that govern the external strengthening techniques of RC beams when subjected to cyclic loading.

This paper investigates the low-cycle fatigue resistance of BS 460B and BS B500B steel reinforcing bars and proposes models for predicting their fatigue life based on plastic-strain (ɛap) and total-strain (ɛa) amplitudes. Constant-amplitude, strain-controlled low-cycle fatigue tests were carried out on these bars under cyclic load with a frequency of 0.05 Hz. The maximum applied axial strain amplitude (ɛs,max) ranges from 3 to 10% with zero and non-zero mean strains. The strain ratios (R = ɛs,min/ɛs,max) used are R =−1, −0.5 and 0. Hysteresis loops were recorded and plastic and total strain amplitudes were related to the number of reversals (2Nf) to fatigue failure and models for predicting the number of reversals to fatigue failure were proposed. It is concluded that the predicted fatigue life of these bars is very accurate when compared with the measured experimental fatigue life results for wide range of values of strain ratios. It is also observed that based on plastic-strain amplitude, BS B500B consistently has a longer life (higher number of cycles to failure) than those of BS 460B for all R values; however, at low plastic-strain amplitudes they tend to behave similarly, irrespective of R value. Other observations and conclusions were also drawn.

This paper develops energy-based models for predicting low-cycle fatigue life of BS 460B and BS B500B steel reinforcing bars. The models are based on energy dissipated in the first cycle, in average cycles and in total energy dissipated to failure for strain ratios R = −1, −0.5, and 0. Upon prediction of the low-cycle fatigue life, the total energy dissipated during the entire fatigue life of steel reinforcing bars can also be predicted based on the predicted fatigue life. The results indicated that the hysteresis plastic strain energy dissipated during fatigue loading is an important and accurate parameter for predicting the fatigue life of steel reinforcing bars and that the predictions based on energy dissipated on average cycles are more accurate than those based on energy dissipated in the first cycle. It is concluded that the strain ratio R has a clear effect on the energy dissipation for both materials where BS B500B dissipated more energy than BS 460B for R = −0.5 and 0 and about the same energy for R = −1 for certain range of fatigue life. Other conclusions and observations were also drawn based on the experimental results.

A harsh environment of temperature (20–54 °C [68–129 °F]) and humidity (80–95%) with the presence of chloride and sulfate make concrete structures vulnerable to deterioration and as a result shorten their service life span. This research has evaluated the durability of normal concrete (NC) and high performance concrete (HPC) made with two aggregates, types AA and AD. Concrete specimens were exposed to saline water in a controlled temperature and humidity environment and tested for initial surface absorption and chloride diffusion. It is observed that the NC and HPC made of type AA aggregates showed lower permeability and lower chlorides diffusion as compared to that made of type AD aggregates. HPC samples produced by the two types of aggregate have consistently shown better durability performance compared to that of NC. The results collected within 21 months period allowed the prediction of chloride diffusion with time for NC. A long term prediction of the chloride diffusion was made to estimate the service life of structures. Experimental observations of s diffusion of NC correlated better with Fick’s Second Law prediction than those of HPC.

Artificial neural network (ANN) has been used in several engineering application areas including civil engineering. The use of ANN to predict the behavior of reinforced concrete (R/C) members, using the vast amount of experimental data as a test-bed for learning and verification of results, proved to be a viable method for carrying out parametric studies. This paper presents application of ANN for predicting the shear resistance of rectangular R/C beams. Six parameters that influence the shear resistance of beams, mainly shear-span-to-depth ratio, concrete strength, longitudinal reinforcement, shear reinforcement, beam depth and beam width, are used as input for the ANN. A back propagation neural network (BPNN) with different activation functions is used and their results are compared. The sigmoid function with variable threshold is adopted due to its accuracy of prediction. The ANN prediction and the measured experimental values are compared with the shear strength predictions of ACI318-02 and BS8110 codes. A sensitivity study of the parameters that affect shear strength of R/C beams is carried out and the underlying complex nonlinear relationships among these parameters were investigated. Shear response curves and surfaces based on these parameters were generated. It is concluded that ANN can predict, to a great degree of accuracy, the shear resistance of rectangular R/C beams and it is a viable tool for carrying out parametric study of shear behavior of R/C beams.

Strengthening and retrofitting structural members using carbon fiber reinforced polymer (CFRP) materials has gained wide acceptance in the civil engineering community because of their superior mechanical properties, light weight, corrosion resistance, and ease of use. Numerous structural reinforced concrete (RC) members have been strengthened with externally-bonded CFRP plates using epoxy adhesives that produce an increase in their load-carrying capacities. However, there are some uncertainties regarding the durability of the bond between the concrete and FRP interfaces when subjected to severe environmental exposure. Most strengthening applications are exposed to outdoor conditions and hence durability under aggressive environments must be considered. This is the subject of this investigation. Several CFRP-concrete prisms have been subjected to several sets of environmental exposure conditions and preloaded with 3 and 5 kN of sustained loading, amounting to approximately 15 and 25% of ultimate lo...

Khartoum, the capital of Sudan, is located at the confluence of White and Blue Niles. The city is heavily populated. Central Khartoum with its high-rise buildings is the center of governmental and business activities and is located on a strip adjacent to the Blue Nile. Geological and geotechnical data indicate that the subsoil conditions at Central Khartoum are characterized by alluvial deposits underlain by Nubian Sandstone at a depth of 25 m. The alluvial deposits, locally known as Gezira formations, consist of clays grading into silt and sand with depth. Macro seismic zonation of Sudan and its vicinities, developed by the authors, gave the ground acceleration at the bedrock surface. The effect of alluvial deposits in Central Khartoum on propagation of seismic motion parameters to the ground surface is investigated in this study. Correlations are proposed for pertinent cyclic soil properties such as shear modulus, damping, and shear wave velocity. The Equivalent-Linear Earthquake Response Analyses (EERA) Model was used to study the effect of local soil conditions on ground-motion parameters. In the absence of strong-motion records in Khartoum, available worldwide strong-motion records are used. Plots showing the time histories of ground motion parameters at the ground surface are obtained. The results indicate amplification of ground motion of up to 4.93. The predicted fundamental period of soils is about 0.5 s which is typical for these types of soils. The maximum spectral acceleration varied from 0.76 to 0.95 g. For design purposes, a response spectrum curve is proposed.

It is fundamental to obtain the natural frequencies and the corresponding mode shapes for cylindrical shells in order to determine their response to different dynamic loading. In this paper an analytical investigation to the free vibration response of moderately-thick shear flexible isotropic cylindrical shells with all edges clamped is presented. The Sander’s kinematic relations for moderately thick cylindrical shell panels are utilized to develop the governing partial differential equations in conjunction with the boundary conditions. A recently developed generalized Navier’s approach, based on a boundary continuous double Fourier series expansion, is used as a solution methodology. A parametric study is presented with respect to various thicknesses, length and radius of curvature of the shell panel. The convergence of the solution method is established numerically for various parametric properties. The present results are compared with the results obtained from finite element method using a four-node isoparametric shell element. The results thus presented should serve as bench-mark solutions for future comparisons with numerical and approximate methods for calculation of free vibration parameters of moderately-thick isotropic cylindrical shells.

This paper presents the seismic hazard assessment and seismic zoning of the United Arab Emirates (UAE) and its surroundings based on the probabilistic approach. The area that has been studied lies ...

The aim of this investigation is to evaluate experimentally and numerically the cyclic loading response of reinforced concrete (RC) beams strengthened in shear with Glass Fiber Reinforced Polymer (GFRP) rods using the near surface mounted (NSM) technique. The experimental results indicated that the use of GFRP rods as NSM strengthening systems can significantly enhance the overall capacity and ductility of shear deficient RC members when subjected to cyclic loading. In particular, the increase in the load-carrying capacity of the strengthened specimens over the unstrengthened control specimen was in the range of 49-66%. Furthermore, the increase in the displacement over the control specimen ranged between 112% and 172%. A 3D finite element (FE) model was also developed to simulate the response of the tested specimens. The developed FE model integrates multiple simulation techniques, nonlinear material properties and corresponding constitutive laws. The models incorporate concrete cracking, yielding of steel reinforcement, bond-slip behavior between NSM reinforcement and adhesive material and between steel reinforcement and adjacent concrete material, respectively. The load-deflection response envelopes and the load-deflection hysteresis loops of the experimentally tested beams and those simulated by the FE models were compared. Good matching was observed between the predicted and measured results at all stages of cyclic loading. (C) 2014 Elsevier Ltd. All rights reserved.

Recent advances in Building Information Modeling (BIM) and the emergence of mandatory building energy codes and specifications encouraged the integration of energy performance rating and energy analysis and simulation in building design and operation. Building Energy Performance (BEP) ratings and simulations and the Architecture, Engineering and Construction/Facility Management (AEC/FM) disciplines are converging. However, current BIM databases contain data that support, mainly, AEC/FM tasks. Few attempts had been made to include data that support BEP rating and simulation. In this study, a conceptual framework for a Building Energy Model (BEM) that captures the data needed for building energy performance rating and simulation has been presented. A case study, using a warehouse, is used as a test-bed for proof of concept and for validation of the developed framework. The ultimate goal is to develop a data model that supports the integration of BEP rating and simulation to facilitate building design and operation.

This paper presents seismic hazard assessment and seismic zoning of Sudan and its vicinity based on probabilistic approach. The area studied lies between 22° E- 45° E and 0° - 24° N. Tectonics of Sudan and its vicinity is first reviewed. An updated NOAA catalogue, containing both historical and instrumental events and covering the period from 700 A.D. to 1993 is then used. Seismic source regions are modeled and relationships between earthquake magnitude and earthquake frequency are established. A modified attenuation relation is used. Seismic hazard assessment is then carried out for 60 km interval grid points. Seismic hazard maps of the studied area based on peak ground acceleration (PGA) for 10% probability of exceedance for time-spans of 50, 100, 200 and 250 years are presented. The results showed that the PGA ranges from 0.02g for low seismic activity regions to around 0.62g for high seismic activity regions. A seismic zone map is also shown for 475 years return period.

WOS: 000325520200005, Bridge constriction in channels usually increases the water level well above the normal depth and may result in overflow on the surrounding floodplain. In this paper, the experimental backwater level at which the maximum afflux value was observed due to bridge constriction was investigated. An artificial neural network (ANN) was used to predict the backwater level based on Manning's roughness coefficient of the main channel (n(mc)) and of the floodplain (n(fp)), bridge width (b) and flow discharge (Q). A multi-layer perceptron (MLP) ANN was used to predict the backwater level using these parameters. Multiple linear (MLR) regression and multiple non-linear regression (MNLR) were used as benchmarks for comparison of ANN results. It is concluded that an ANN can very accurately predict the backwater level. The developed ANN model was then used to conduct a parametric study to investigate the influence of n(mc), n(fp), b and Q on the backwater level due to a bridge constriction without piers. It is concluded that n(mc) and Q have a more profound effect on the backwater level than does n(fp), while b has very little effect on the backwater level within this range of parameters. Other observations and conclusions are also drawn.

Object-oriented principles have introduced several useful concepts for developing complex software systems. As a result, several methodologies have been suggested for the overall design of software systems based on these concepts. Methodologies and frameworks for designing objects that are to be part of the software systems are currently lacking. This paper proposes anobject design framework andmethodology, which utilizes the object-oriented concepts, for planning, organizing and designing structural engineering design objects. Design objects in an integrated structural engineering system are complex and often related to each other in various different ways. The paper also identifies several important relationships among structural engineering design objects. These relationships serve as communication channels through wich design objects send messages to and receive responses from each other. Several examples, drawn from reinforced concrete structures, will be presented to demonstrate the object design methodology and to illustrate how the framework is effective in reducing the complexity of design objects in an integrated structural engineering system.

This paper investigated the influence of local geotechnical and geological soil conditions on the intensity of ground shaking of Dubai-Sharjah metropolitan area (DSMA). Acceleration-time histories of Dubai and Sharjah were chosen according to spectral shape and similarity in magnitude and distance to a target response spectrum that were obtained from the results of Seismic Hazard Analysis (SHA). Subsurface geotechnical data of 72 different sites, located in the area under consideration, were used in this study. The effect of local site conditions on ground response during earthquake has been evaluated by performing equivalent linear analysis. Dynamic properties of selected soil profiles were evaluated using empirical relations between Standard Penetration Test (STP) N-values and shear wave velocity (Vs). Modulus degradation and damping curves for sand and rock were also employed in the analysis. Results indicated that surficial deposits in the area amplified earthquake ground motion. The peak amplification was observed over relatively narrow frequency range of 1.5-5 Hz (0.2-0.8s period) that was found to represent the predominant frequency range of the site classes under consideration. Amplification factors at PGA and at both short and long periods (0.2s and 1.0s), which are site class dependent, were compared to the current code of practice.

The use of externally bonded carbon fiber-reinforced polymers (CFRPs) as strengthening systems to improve the condition and overall capacity of existing reinforced concrete structural members is found to be a promising scheme. This field has drawn the attention of many researchers in the past two decades through the implementation of much theoretical work as well as experimental studies. It was evident through many experimental investigations conducted by a number of researchers that the bond action between fiber-reinforced polymers and reinforced concrete members is considered one of the main factors affecting the performance and reliability of external strengthening systems and warrants further investigation. Debonding failure is a brittle mode of failure that may occur prematurely before strengthened members develop their full composite and expected capacities. This paper aims to investigate the bond behavior between the CFRP-concrete interface via experimental work and finite element (FE) simulations. The experimental study consisted in testing nine concrete prisms with different bonded lengths of the CFRP plates that vary between 25% (60 mm), 50% (120 mm), and 75% (180 mm) of the total length of the concrete prisms and instrumented with strain gauges. A FE simulation model was created and validated using the experimental results of the tested specimens, and a parametric study was carried out to investigate the effect of several parameters on the bond behavior between CFRP and concrete surfaces. The trend of the FE simulation results shows a good agreement with the experimental results and those available in the literature. It was observed that the optimum length of the CFRP plate is in the range between 150 mm and 160 mm when bonded to concrete surfaces. Other conclusions and observations were drawn based on the experimental and numerical results.

An artificial neural network (ANN) can help in the prediction of advanced water treatment effluent and thus facilitate design practices. In this study, sets of 225 experimental data were obtained from a wastewater treatment process for the removal of phosphorus using oven-dried alum residuals in fixed-bed adsorbers. Five input variables (pH, initial phosphorus concentration, wastewater flow rate, porosity, and time) were used to test the efficiency of phosphorus removal at different times, and ANNs were then used to predict the effluent phosphorus concentration. Results of experiments that were conducted for different values of the input parameters made up the data used to train and test a multilayer perceptron using the back-propagation algorithm of the ANN. Values predicted by the ANN and the experimentally measured values were compared, and the accuracy of the ANN was evaluated. When ANN results were compared to the experimental results, it was concluded that the ANN results were accurate, especially during conditions of high phosphorus concentration. While the ANN model was able to predict the breakthrough point with good accuracy, the conventional advection–diffusion equation was not as accurate. A parametric study conducted to examine the effect of the initial pH and initial phosphorus concentration on the effluent phosphorus concentration at different times showed that lower influent pH values are the most suitable for this advanced treatment system.

The ultimate bond strength between Fiber Reinforced Polymers (FRP) and concrete is one of the most important elements in the performance of the strengthened beam and its failure mode and failure mechanism. In this investigation an Artificial Neural Network (ANN) model has been developed to predict the ultimate bond strength (P u ) between FRP and concrete based on several factors that influence it. These factors, which were used as input to the ANN, include concrete prism width (b c ), concrete compressive strength (f cu ), concrete tensile strength (f t ) as well as the FRP thickness (t f ), width (bf), tensile strength (f f ), elastic modulus (E f ) and the bond length (L) between FRP and concrete. The ANN predicted ultimate strength loads were compared with experimental values. It is concluded that the ultimate bond strength predicted by the ANN model are reasonably accurate compared to the experimental values and the accuracy can be further improved by using sufficient data generated by similar standardized tests. Based on the developed model, a parametric study can be carried out to investigate the influence of several parameters on the ultimate bond-strength between FRP and concrete and on the behaviour of bond slip compared to existing models.

Object-oriented approaches have emerged as one of the most promising paradigms for developing software. The approach has gained popularity in a number of fields in computer science, such as programming languages, data bases, artificial intelligence, knowledge representation, office automation, and computer-aided design (CAD). Recently, object-oriented approaches have been applied to develop integrated computer-aided civil engineering systems. This paper describes our experience developing software using an object-oriented approach to integrate finite element and graphics application programs, which are to become parts of an integrated civil engineering system. The short-term objective of the project is to develop a general-purpose data-translation facility for finite element and graphics-based programs. The long-term objective of the project is to investigate the effectiveness and viability of object-oriented approaches to integrate programs from various activities in engineering of a constructed facility. Our experiences have resulted in several practical ideas and revealed some points that are difficult to comprehend without actually going through the entire software development process.

Accurate, efficient data exchange is vital to improving productivity in the architectureengineeringconstruction industry. Much of the current work in data exchange is focused on the development of ...

As design objects are created during the design process, it is not sufficient to represent only a single current state of each object. Instead, it will usually be necessary to represent a number of past and current states, existing parallel to each other at various design stages. This requirement has led to the development of various schemes to help manage and control multiple occurrences of a design object.