Performance of Precast Thin Panel as Permanent Formwork for Precast Composite Slabs

This study investigates the performance of precast thin panel as permanent formwork for precast composite slab. The two-way inverted ribs in the thin panel are placed to enhance its flexural stiffness, as well as providing link between the precast layers. Flexural behaviors of two precast panels are investigated under two line load and distributed load. Test results indicate that the thin panel with suitable ribs layout and support distance can be used as permanent formwork. Typical load from construction worker and in situ elements could be sustained by the panel

Condition Assessment of Existing Reinforced Concrete Bridges in Albania

Conditions of existing bridges are often problematic issue for many countries. The combination of a variety of local factors that cause deterioration raises the needs for local survey for bridges. Concrete bridges in Albania had been constructed with different standards in different periods and exposed traffic loads which have rapidly increased last two decades. Despite the fact that existing condition of these bridges has not been clearly defined yet. Therefore an attempt was made on this study to draw a general picture of Albanian’s reinforced bridges. The condition of Albanian bridges was presented in this paper based on visual inspection of 24 bridges (3.6 km of total bridges length) from different part of the country, concentrating on local causes of deteriorations. The main causes of the defects are figured out in the study as traffic load, nature force, aging, lack of maintenance and last but not least construction and design deficiencies. Study concludes that general physical state of the bridges are poor, therefore, the service provided by the bridges are in potential hazards

Development Of An Expert System For Assessment Of Reinforced Concrete Bridge Condition

Condition assessment of Reinforced Concrete Bridge is a complex subject imbued with uncertainty and vagueness. This complexity arises from numbers and relations of problems in reinforced concrete bridges. Condition assessment process requires deep knowledge of the behavior of Reinforced Concrete Bridge, awareness of change, good understanding of design process and skillful person. This requirement can be achieved through a comprehensive expert system, which may represent human expertise. The aim of this project is to develop an expert system for condition assessment of reinforced concrete bridges. The system should be an efficient tool to guide the field inspectors during identification of potential problems associated with existing reinforced concrete bridges. It is developed by integrating the existing condition assessment procedures by the Public Work Department (JKR), which is only based on visual inspection, and the results obtained through non-destructive test (NDT) techniques and finite element analysis.The system has been successfully developed. Its final output, which not only is displayed on the monitor but also can be saved in a computer file and sent to a printer. Having this computation power, one file is created for each bridge at a particular area and quantitative comparison can be done faster and much more precisely than the available methods of condition assessment

Applications of Artificial Intelligent Systems in Bridge Engineering

Condition assessment of reinforced concrete bridges is a complex subject imbued with uncertainty and vagueness. This complexity arises from numbers and relations of different kindof problems in reinforced concrete bridges. Condition assessment requires vast knowledge of the behaviour of reinforced concrete structures subjected to different phenomena such as excessive loading, environmental effects and chemical attacks. This requirement can be achieved through an expert system, which may represent human expertise. This study present an Artificial Neural Network (ANN) assisted crack rating system for RC bridges' girder which improves the effectiveness of crack condition rating. The ANN system was developed as an alternative to traditional crack rating methods. The rules for the ANN system were constructed from expert knowledge, technical books and inspection results of 5 different RC bridges. The results obtained by ANN model show high correctness ratio conformity to crack rating obtained by the traditional inspection methods

Structural Performance Of A Lightweight Composite Slab System

Floor structure occupies the biggest dead load and volume in most of the residential buildings. Composite structure is the most proper concept to obtain lighter, cheaper and easy to construct floor system by optimally utilizing available materials. However, composite floor system efficiency under ultimate load remains a major concern. Longitudinal shear failure is the most common type of failure in composite floor slab. The existing shear links systems between cast in situ and precast layers are found very conservative due to absence of adequate investigation. Further investigations of connection systems between the precast composite units are sought. Therefore, Composite Ferrocement Masonry Slab (CFMS) is introduced as a new composite floor system in this study. Inverted two-way ribs precast ferrocement thin panel is used at tension part of the composite slab system and act as permanent formwork. Masonry element such as brick and autoclaved aerated concrete with concrete mortar are used as toping of the composite floor system to achieve lighter structure.Analytical study has been carried out to investigate the efficiency of Composite Ferrocement Masonry Slab as a composite floor system. A series of pilot tests have been conducted until ultimate load to ascertain structural characteristic of both precast and full slab system. The study proposes a new system to transfer the horizontal shear between the interfaces of the precast and cast in-situ layers of concrete slab as a substitute of shear links. The proposed system implements an interlocking concept and does not require any shear reinforcement. Experimental work carried out by pure shear loading (push off test) and flexural loading to study the effectiveness of the interlocking mechanism in transferring the stresses developed due to the applied load. Flexural test was carried out on full size specimens using different masonry elements to explore structural capacity. Finally, connection tests were carried out for slab to slab and slab-beam-slab connection for the composite precast slab system. The results in terms of strain distribution, load-deflection and failure loads indicate that the response of the composite slab to the flexural loading is satisfactory and can be used as a floor slab in residential buildings. The predicted ultimate load using BS8110 was found to be compatible with the experimental results. Ductile load deflection curves were drawn for the composite slab implied maximum deflection varied between 31 to 35 mm for 3 m span. The interlocking mechanism in the proposed composite slab system implied that 20 mm and above interlocking depth is enough to support maximum possible horizontal shear load on the slab structure. The composite slab system with interlocking mechanism acts as a full composite structure until ultimate load. The flexural capacity of this floor slab system is adequate to carry ultimate load 6.5 kN/m2 for brick masonry composite and 4.5 kN/m2 for (Autoclaved Aerated Concrete) AAC masonry composite. The composite slab is achieved using brick and AAC masonry 18% and 22 to 34 % lighter compare to RC slab respectively. The connection tests ascertain connectivity of the composite slab-beamslab system is well enough to carry residential loads. As a result the proposed composite slab systems may be used as composite precast slab for residential buildings

Compromises in FIR matched filter design

With duration-limited signals there is the opportunity for perfect matched filtering by a suitable FIR filter, providing the noise can be construed as being supplied through an all-pole coloration filter. The popular matrix solution formulation does not make it obvious just what size the optimal filter length must be, and the signal vector zeropadding mechanism needed for coaxing out the optimal coefficient vector is also unclear. Difficulties are compounded when the filter length allowable for implementation falls short of the optimal length. Worse yet, if it happens that the noise is shaped by a coloration filter which has some zeros (i.e., is MA or ARMA instead of just AR), then any FIR filter can only be an approximation to the ideal IIR matched filter. In either case, decreasing filter length requires compromise strategies that are not at all transparent. We base our analysis approach to the FIR problem setup in terms of (time) correlations and convolutions in which the whitening filter has the central role. It is then easy to see that both "pole-only" and "some-zero" noise cases yield optimal SNR values that are exactly calculatable by a time-domain scalar product. The inevitable degradations of SNR with decreasing FIR filter lengths are, in turn, readily quantifiable. We study several compromise strategies arising from the whitening filter convolution approach and find (albeit with a very limited set of test cases) that they are not attractive when contrasted to the common matrix solution. The matrix solution itself, meanwhile, is shown to demand close attention to zeropadding patterns employed in it if best performance is to be obtained as filter length is reduced. Fortunately, exhaustive zero-padding assessment is a practical proposition, and this is our recommended procedure at this early stage of investigation

Strengthening and Restoration of Historical Structures - Mirahor Ilyas Beg Mosque in Korca

The Mirahor Ilyas Beg Mosque, built in 1496 in Korca, is one of a few Ottoman mosques still existing in Albania and the only Ottoman monument in the city. The mosque was built using cut stone and brick. It has a strong image; a cubic mass rising over a square plan. Inside there are found pictures of the mosque in the past and different famous mosques. During its existence, it was damaged from many earthquakes occurring at this area. Due to amortization, the mosque's structural properties were weakened and architectural values were dimmed. Proper strengthening methods need to be applied, not only to improve structural conditions, but also to preserve architectural features of the mosque. In this paper assessment of existing conditions of the structure is carried out. Based on the obtained results, solutions for the structural problems are investigated. As for restoration, repair methods to be applied were examined taking into consideration at what extent the historical values of the building will be preserved. The proposed strengthening methods are the ones which would affect the least the mosque's historical values

Determination of Fundamental Properties of Masonry for different cities of Albania

This study deals with the properties of unreinforced masonry. Masonry is a two phase material, and the properties of the assemblage depend on that of bricks and mortars. On the other hand, the quality of bricks mostly depends on the type of raw material and the production process. The quality of mortars is more complicated to assess since it depends on its mix design, which is highly variable from batch to batch. The procedure of assessment of properties for bricks and prisms is well established in various standards while the compressive strength of existing mortars has always been a challenge. In Albania there are a considerable number of URM structures and therefore assessing the properties of masonry is an important task. Therefore, samples from Tirana, Vlora, Elbasan, Rreshen and Bulqiza are obtained and tested, mainly in compression to assess the compressive strength of bricks and mortars. Large and highly populated cities are targeted. The expected outcome of this experimental program is the set of mechanical properties of unreinforced masonry for the selected cities, confronted with the design values provided by production factories and theoretical values

Conditional Assessment of Historical Structures: Earthquake Performance of Naziresha Mosque

The Naziresha Mosque is one of the most important historical buildings built during the Ottoman period, still functional in Albania. It is located in Elbasan, a city in the center of Albania. Naziresha mosque was built during 1590s. It has a square plan and a cubic shaped central hall. Though it is a historical monument with unique architectural properties, the current structural condition of the mosque is observed to be severe. Furthermore, the mosque is found in an active seismic area. In this paper, conditional assessment of the mosque and structural behavior is investigated to identify the weak locations of potential failure in the structure. The static behavior and performance under earthquake load of the mosque have been evaluated using the finite element modeling technique, where the behavior of masonry has been taken into account by proper constitutive assumptions. It is believed that the case studies conclusions are applicable to most of Ottoman period mosques in Albania. As a result, significant information on the understanding of the actual structural behavior of historic buildings is presented to provide effective solutions

Analytical and Experimental Behavior of a Novel Anchorage Layout for FRP Confined Rectangular Columns

In the last two decades, FRP systems have been largely used to improve the performance of structural members, due to their high strength to weight ratio and corrosion resistance. Application of this strengthening procedure in circular columns has resulted quite beneficial in increasing their seismic and axial capacity. Whereas in the rectangular ones, strength enhancement was considerably less. Hence this paper aims in introducing the FRP strengthening mechanism of rectangular columns and highlighting its limitations in strength enhancement when compared to the circular counterparts. The corner radii, aspect ratio and concrete compressive strength effect on the capacity increase rate are evaluated as well, based on the results of the large database provided by different experimental studies performed until now. A novel anchorage configuration is suggested to overcome the existing limitations for enhancement of axial strength in this column category. Analysis of the improvement that this solution provides to the confinement pressure distribution was performed by ANSYS Software. Experimental and analytical results supported the increase of stress distribution uniformity in the anchored rectangular column section