Cost Aanalysis and Comparison of Rectangular and Trapezoidal Box Girder Section

The present study aims at design, analysis and parametric comparison of two different cross section of box girder deck system. Objectives of this study are to compare the stresses at important location like top slab and bottom slab using analysis tool MIDAS-2016. And design and estimates different sizes of rectangular and trapezoidal box girder section using hand calculation. Keywords: Box Girder, Rectangular box girder, Trapezoidal box girder and MIDAS-2016

Influence of Skew Angles on Box Type Bridge

In the present study, modeling and analysis of a three-lane three-span box bridge has been carried out by using finite element software STAAD pro.v8i. The study has been execute to find the effect of skew angle on all bride slabs (top slab, bottom slab, outer walls, inner walls) under various loads (dead load, live load, surfacing load, earth pressure, temperature and live load surcharge) and their combinations using IRC 6:2016. Skew angles taken for study ranges from 00 to 700 with an interval of 100 . Parameters that are mainly examined are longitudinal moments, transverse moments, torsional moments, shear forces and displacements. It has been observed that with the increase of skew angle all the parameters increases with the increase of skew angles in all slabs.

Research and Application of Anti-floating Schemes of Deep Foundation Pit of Subway for Underwater Excavation and underwater concrete sealing

To implement deep foundation pit of subway construction with underground continuous wall adopting underwater excavation and waterproofing concrete bottom sealing curtain, the depth of bottom concrete must first meet the anti-floating requirements of the foundation pit. Since the elevation of the bottom slab of the station is certain, the thicker the sealing concrete, the deeper the excavation depth of the foundation pit, the greater the buoyancy of the water to be withstood, and eventually the thicker the sealing concrete, so the selection of foundation pit anti-floating scheme is very critical. This paper combines the practical construction of the deep foundation pit of the main structure of Yongdingmenwai station which is in the third phase of Beijing Metro Line 8 construction project, and analyzes and compares the anti-floating scheme of the foundation pit, so as to select a more reasonable anti-floating scheme, in order to apply experiences for future similar projects and construction.

Experimental analysis of gradient of negative temperature for polypropylene fiber concrete U-shaped girder

To study the negative temperature gradient models of a rail transit U-shaped girder during the winter season, a U-shaped rail transit girder was researched in Qingdao. The temperature field of the midspan section was observed for a 48-h period during the winter. The maximum vertical and horizontal temperature difference distributions were obtained, and the negative temperature gradient models for the winter were established. The results show that the vertical temperature gradient models of the web and bottom slab should be considered. The vertical temperature gradient model of the web is a piecewise function composed of exponential and linear functions. The vertical temperature gradient model of the bottom slab is an exponential function. The transverse temperature gradient of the web is obvious, whereas the transverse temperature gradient of the bottom slab is slight.

Research on the anti-cracking ability of large composite girder cable- stayed bridge

<p>Recently, composite girder cable-stayed bridge is widely used in the world. Since the existing design method takes less focus on the principal stress of the top and bottom slab, the cracking problem of the concrete bridge deck has not been solved perfectly yet. Based on the spatial grid model, this paper takes Guan He Bridge in Jiangsu province as an example to analyze this kind of structure. Monitoring the principal stress of the concrete bridge deck is proposed for the first time to study the effect of diagonal crack. The principal stress of the concrete deck in the middle span, the quartile span, one-eighth of the span, the side span, the bridge tower, and the auxiliary pier are observed respectively. Comparing the theoretical values with the measured value, the results show that the actual stress state of the whole concrete bridge deck during construction is in accordance with the theoretical calculation. For composite girder cable-stayed bridge, the concrete bridge deck is prone to crack, so it is very significant to control the quality in the construction stage, which can provide a guarantee for the safety and durability of the structure.</p>

ОКРЕМІ ПИТАННЯ АНАЛІЗУ УШКОДЖЕНЬ БУДІВЕЛЬНИХ ОБ’ЄКТІВ ВЕЛИКОЇ ПЛОЩІ

У роботі представлений перелік проблем, що супроводжують будівельні об'єкти великої площі, в тому числі й підземні гаражі. Здійснено технічний аналіз окремих проблем, що виникають в таких будівлях під час їх експлуатації. Проектування, а пізніше і будівництво підземних гаражів найчастіше, пов'язане з вирішеням складних інженерних питань. Згідно з ними до найпоширеніших конструкційних недоліків у підземних гаражах віднесні: тріщини нижньої плити, порушення поверхових перекриттів, невластиве кручення бетону, відсутність дилатації або також помилково прийняті ґрунтово-водні умови.The paper concerns complex engineering challenges associated with multi-storey underground car parks. An analysis of selected issues in underground garages during the exploitation was performed. The design and implementation of structures of which function are underground garages is most often associated with serious engineering challenges. For structural reasons frequently occurring faults in garages may include fracture of the bottom slab and intermediate floors resulting from improper design of reinforcement, concrete shrinkage, lack of expansion joints or incorrectly adopted soil-water conditions.

Strengthening of a railway arch bridge from 1854

This paper presents the inspection of the condition and the design for strengthening of an existing railway arch bridge constructed in 1854. The original arch bridge is constructed with 5 layers of bricks in the arch and granite blocks in the foundation on top of an arrangement of frame made of timber and carried by piles. From the inspection it was concluded that the bricks in the arch was damaged due to freeze-thaw. It was also concluded that the timber structure in the foundation was rotten. The bridge is crossing a small creek. The environment is very sensitive. The access to the construction site is passing through landscape subject to preservation. The strengthening project included the arrangement of a new reinforced concrete arch. The arch was anchored with glued reinforcement bonded to the existing brick arch. The reinforcement and formwork was placed above the creek without disturbing the fauna in the water. The concrete was pumped into a form under the existing arch. After curing of the concrete arch, the strengthening of the foundation was initiated. It was planned to construct a bottom slab under the creek, which was able to carry the new concrete arch. In order to get access for the construction work the creek water was pumped through pipes suspended under the top of the new concrete arch. The procedures to handle the very delicate situation of replacing the foundation, while the bridge was in operation, and also protecting the environment is described in detail in the presentation. The process included high speed concrete curing, working processes under extreme narrow conditions and a very tight schedule.

Numerical Study of Seabed Boundary Layer Flow Around Monopile and Gravity-Based Wind Turbine Foundations

Computational fluid dynamics (CFD) has been used to study the seabed boundary layer flow around monopile and gravity-based offshore wind turbine foundations. The gravity-based foundation has a hexagonal bottom slab (bottom part). The objective of the present study is to investigate the formation of horseshoe vortex and flow structures around two different bottom-fixed offshore wind turbine foundations in order to provide an assessment of potential scour for engineering design. Three-dimensional CFD simulations have been performed using Spalart–Allmaras delayed detached eddy simulation (SADDES) at a Reynolds number 4 × 106 based on the freestream velocity and the diameter of the monopile foundation, D. A seabed boundary layer flow with a boundary layer thickness D is assumed for all the simulations. Vortical structures, time-averaged results of velocity distributions and bed shear stresses are computed. The numerical results are discussed by studying the difference in flows around the monopile and the gravity-based foundations. A distinct horseshoe vortex is found in front of the monopile foundation. Two small horseshoe vortices are found in front of the hexagonal gravity-based foundation, i.e., one is on the top of the bottom slab and one is near the seabed in front of the bottom slab. The horseshoe vortex size for the hexagonal gravity-based foundation is found to be smaller than that for the monopile foundation. The effects of different foundation geometries on destroying the formation of horseshoe vortices (which is the main cause of scour problems) are discussed.