Effect of Niche-Tunnel Face Distance and Excavation Time in Tunnel Construction

Estimated time and costs of construction are one of the most important factors influencing the decision whether and how a tunnel is to be built. Underground excavation works carry a lot of uncertainties that effect the time and cost of tunnel construction so it is essential to make the decisions based on the past best experiences. This study has analyzed the time needed to load the muck in truck, measured in 89 tunnel faces which have different distance from tunnel face to nearest niche, measurements are done in excavation phase of 10.245,00 meters of tunnels which have different diameters varying from 4,20 to 9,40 m. Results indicate that the best distance between tunnel face and niche increase linearly the time of excavation from 0 to 200 meters and exponentially for distances longer than 200 m. It is concluded that in small and medium diameter tunnels the optimal excavation time is achieved when distance from niche and tunnel face is not longer than 200 meters

The Effect of Concrete Sample Size in the Compressive Strength Value of Concrete

Concrete is one of the most widely used construction materials. Compressive strength is one of the most important properties of hardened concrete. Different codes use different standards to define the characteristic strength. Albania nowadays is adapting the EN standards, but previously it used to apply the local code KTP. According to KTP standards the concrete samples were cubic specimens of 200mm side length. This study is an attempt to analyse the relation between sample size and compressive strength values of concrete specimens. For this purpose, 4 concrete classes of C8/10, C16/20, C20/25, C30/37 and 5 different cubic sizes of 50, 100, 150, 200, 250mm side length were investigated. The samples were taken according to EN 206-1. Six samples were tested for the determination of the compressive strength value of each class/size combination. According to the compressive strength test results the values increase as the size increases up to 150mm, but as the cube size continues to increase the compressive strength values decrease gradually

Deficiencies Of Some Important Bridges In Albania

Over the past decades Albania has built many new bridges and roads. The construction of these bridges and roads has been done under different periods and characterized from different types of construction codes. The work reported on this paper was carried out to survey the present condition of three important bridges in national roads of Albania. Literature review was carried out to identify common defects on same type of bridges. Interviews were conducted with different engineers worked on similar type of bridges' design, construction and inspection in Albania. Site inspections of these three bridges were carried out to identify defects on the bridges. The study was extended to inspect all the members on the bridges to define causes of the defects. The main causes of the defects were classified as; lack of detailing in design, poor quality of construction, poor concrete quality, inadequate concrete cover, water leakage and last but not least lack of maintenance. These bridges are classified as poor or very poor conditions based on visual inspection in the study

Effect of Scour on Load Carry Capacity of Piles on Mat Bridge

Critical scour effects on bridge performance helps to predict the bridge load carryingcapacity and as a result, may help prevent unnecessary looses. Very few studies have beenconducted on current condition of Albanian bridge especially on integrations between water,pile foundation and bridge structures. Most of highway bridges in western and center Albaniaare over shallow water, including small creeks, wetlands and marshes. A widely used designand construction procedure for these bridges is to have the bridge superstructure supported onpile bents. Albanian rivers have aggressive flow regime. During major flood events, thevolume and velocity of flood waters can cause considerable scouring. As the load carrycapacity of these pile bent vary inversely with the bent height, a scour in certain height willreduce its load carry capacity.This paper analytically summarizes the effect of the scour on pile bent load carrycapacity. Load carry capacity of piles is calculated analytically, only geotechnical data aretaken from site tests. Site inspections on Mat bridge show that 19 from 32 pile bents haveserious scour problems. Analysis results indicate that pile bents due to scouring height haveloosed a load carry capacity varying from 17.64 to 32.11% of that designed

MOVING THE CENTER: THE RELATIONSHIP OF URBAN PLANNING, ARCHITECTURE AND CIVIL ENGINEERING PROJECTS WITH THEIR BENEFICIARY

Terms such as quality deviations, non-conformances, defects, quality failures, over budget and behind schedule are quite frequent in urban planning, architecture and civil engineering projects. The effort to analyze the parameters affecting quality, budget, schedule and functionality failure and/or diversion in construction industry is extensive. Nevertheless, the number of construction projects that have functional deficiencies minimally in one of their complementary elements is significant. The main reasons behind these deficiencies are considered to be the lack of experience, ineffective interaction of clients-consultantscontractors and corruption. This article attempts to shed light to another reason why construction projects fail to fulfill some of their main functional parameters, emphasizing that this is caused by an inconsiderate approach of the ones in charge of planning and building structures to their beneficiaries. In other words, urban planners, architects and civil engineers approach the structure in hand as “the center of the world”. This is somehow reflected in the structure which tends to demonstrate an Othering attitude, similar to that of the (former) colonizer to the (formerly) colonized, to their surroundings and beneficiaries

Assessment of Reinforced Concrete Bridge Deficiencies Under Service Loads

Conditions of existing bridges are often problematic issues and expensive to resolve for many countries. In order to anticipate and reduce these problems, the combination of various general and local factors causing degradation needs to be identified in the early stage. The identification of these problems reveals the need for local research and detailed inspection for bridges. Reinforced Concrete Bridges in Albania were built at different standards in different periods and were exposed to rapidly increasing and changing traffic loads in the last three decades. This situation made the structural assessment of the bridges inevitable in the local conditions. Although the existing condition of these bridges had not been clearly defined, after democratization and joining the European Council (the 1990s), new bridges were rapidly built and existing bridges were strengthened with different methods. In this context, the structural condition of existing reinforced concrete bridges in Albania was examined in this study. The condition of Albanian bridges was presented in this paper based on visual inspection of 104 bridges covering the total length of 7271.6 m along 263 km road from different parts of the country, concentrating on local causes of deteriorations. The main causes of the defects are figured out in the study as traffic load, natural force, aging, lack of maintenance, and last but not least construction and design deficiencies. The study concludes that the general physical condition of the bridges is poor, so the services provided by the bridges are potentially at risk. The results obtained at the end of this study may be valid for countries with similar features, e.g., other Balkan countries