Field Static load Effect on Performance of Hollow Section Girder Bridge Subjected to Fire (Part A)

Hollow Bridge section inspection was carried out in this study and different reasons may cause major failure of bridge. The field inspection of bridge structural elements has been paying more attention of engineering academic researchers. The bridge has been exposed to fire accident in additional to the excessive load and environmental factors effects. This study dedicated for inspection the White River Bridge elements (Bai xi da Qiao/ China) including the essential damage in main girder , concrete spalling, deformation due to deflection and excessive stress and strain, deck slab and concrete cover, steel corrosion…..etc. The analysis of field test evaluates the performance of whole structure of bridge element under static load test. The investigation results shows that the bridge has minor defects through the substructures such as there is no major corrosion of reinforcement and the concrete in a good condition. The upper structure depending on analysis field test of deflection and strain at the critical section, that the main girder has no enough capacity and need to be strengthened

A Review on Flat Slab Punching Shear Reinforcement

يتكون نظام البلاطة المسطحة من صفيحة خرسانية مثبتة على أعمدة دون وجود عتبات. خلال القرن الماضي، استخدمت البلاطات المسطحة على نطاق واسع في أنواع مختلفة من المباني. بشكل عام، تصنع البلاطات المسطحة من مواد هشة ذات عمق محدود؛ وبالتالي، قد تخضع للفشل بسبب قوى القص أو انحرافات عالية. ولذلك، يجب اخذ هذه المعايير بعين الاعتبار عند تصميم البلاطات المسطحة وان تجاهل اي منهما قد يؤدي إلى انهيار العديد من المباني كما حصل في الماضي. لتحسين أداء البلاطة المسطحة ضد الفشل نتيجة قوة الاختراق اوالانحرافات، لا بد من توفير تسليح إضافي في منطقة العمود. في هذا البحث، سيتم تقديم مراجعة لدراسة آلية قص الاختراق في البلاطات المسطحة ووصف أنواع التسليح المختلفة التي تستخدم في التعزيز ضد قص الاختراق.Flat slab system is a concrete plate propped on columns without the existence of beams. During the former century, flat slabs have been used widely in different building types. In general, flat slabs are made from brittle materials and also have a finite depth; thus, flat slabs may undergo to fail due to punching shear or high deflections. Therefore, these criteria should be considered in the design of flat slabs and ignoring both of them had led to several crumbling down to many constructions in the past. To enhance the flat slab performance against failure due to punching and deflections, additional reinforcement should be supplied in the column region. In this paper, a review is presented to study the mechanism of punching shear in flat slabs and describe different types that used for reinforcement against punching shear

High Strength Concrete Beams Reinforced with Hooked Steel Fibers under Pure Torsion

A study of the behavior of fibers in high-strength reinforced concrete beams is presented in this paper. Twelve reinforced concrete beams were tested under a pure torsion load. Different compressive strengths (45.2, 64.7, and 84.8 MPa) and fiber volume fractions (0, 0.25, 0.5, and 0.75) with variable spacing between transverse reinforcements have been used. It was discovered that the maximum torque of a high-strength concrete beam is increased by about 20.3, 25.6, and 27.1% when the fractional volume of fiber is increased from 0 to 0.25, 0.5 and 0.75 respectively (when the compressive strength is 45.2 MPa and the transverse reinforcement spacing is 100 mm). The test results show that the ultimate torsional strength becomes higher when the concrete compressive strength increases, and this percentage increase becomes higher with increasing steel fiber volume fraction. When the spacing between transverse reinforcements decreases from 150 to 100 mm, the ultimate torque increases by 19.9%. When the spacing between transverse reinforcements decreases from 100 to 60 mm, the ultimate torque increases by 17.0%. In these beams, the fibers’ compressive strength and volume fraction were kept constant at 45.2 MPa and 0.75, respectively. Doi: 10.28991/CEJ-2022-08-01-07 Full Text: PD

Evaluation the effectiveness of a non-chopped basalt fiber and water-based of isocyanate-polyester polyol prepolymer on the properties of cement fiberboard

Abstract Cement board reinforced with basalt fibers were prepared by using polymer compounds, 5% of water-based of isocyanate-polyester polyol prepolymer blend was used as a fixed percentage, and the rates of basalt fıber used were 5%, 7.5%, 10%, 12.5%, and for each of them used water/cement ratios (W/C) as 1.4, 1, 0.75, 0.4, and 0.5 respectively. The sample cured for 28 days, and the mechanical and physical properties of cement fiberboard were greatly improved due to additional fibers in cement compounds, the tests procedures of properties were carried out according to ASTM standard c-1185. It results reveals that 12.5% is the best percentage, in bending resistance, water absorption percentage, and the moisture content have improved, but it showed less thermal conductivity compared to other ratios, furthermore the compressive strength was improved. It is essential to indicate when increasing the polymer ratio, leads to a certain decrease in mechanical properties but improves the wetting surface of the basalt fibers and adhesion to cement. Therefore, a 5% polymers ratio chooses and the basalt fıber mix proportions changed to enhance the mechanical and physical properties of fiber boar

Flexural behavior of two-layer beams made with normal and lightweight concrete layers

In this paper, twelve concrete beams with two different layers of concrete were evaluated as a simply supported beam under four-points loading. The beams assembled of two different types of concrete layers, one of which was normal-weight concrete (NWC) and the other was lightweight aggregate concrete (LWAC). The investigated parameters were the thickness of the lightweight concrete to the overall depth of beams (hLW/h), and the compressive strength of normal and lightweight concrete. Due to the weak lightweight aggregates used, lightweight aggregate concrete exhibits more brittleness and lower stiffness. Therefore, the viability of compensating for this degradation and providing a layer of normal concrete seems to be very interesting in such beams. The behavior of beams was evaluated based on cracking, failure mode, flexural strength, maximum deflection, stiffness, and toughness. The results showed slight variations on the majority of the above-mentioned performance aspects of two-layer beams compared to fully normal concrete beams. While there were great enhancements compared to fully LWAC beams. The variants were mainly attributable to the efficacy of using LWAC in providing lower stiffness and lower tensile strength. The experimental results have been compared to predicted values using the ACI 318-19, with some modifications for the equations to be matched with two-layer beams, the comparison was in terms of the deflection due to service load, moment capacity, and cracking moment

Combinations of single-top-quark production cross-section measurements and vertical bar f(LV)V(tb)vertical bar determinations at root s=7 and 8 TeV with the ATLAS and CMS experiments

This paper presents the combinations of single-top-quark production cross-section measurements by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at = 7 and 8 TeV corresponding to integrated luminosities of 1.17 to 5.1 fb(-1) at = 7 TeV and 12.2 to 20.3 fb(-1) at = 8 TeV. These combinations are performed per centre-of-mass energy and for each production mode: t-channel, tW, and s-channel. The combined t-channel cross-sections are 67.5 +/- 5.7 pb and 87.7 +/- 5.8 pb at = 7 and 8 TeV respectively. The combined tW cross-sections are 16.3 +/- 4.1 pb and 23.1 +/- 3.6 pb at = 7 and 8 TeV respectively. For the s-channel cross-section, the combination yields 4.9 +/- 1.4 pb at = 8 TeV. The square of the magnitude of the CKM matrix element V-tb multiplied by a form factor f(LV) is determined for each production mode and centre-of-mass energy, using the ratio of the measured cross-section to its theoretical prediction. It is assumed that the top-quark-related CKM matrix elements obey the relation |V-td|, |V-ts| << |V-tb|. All the |f(LV)V(tb)|(2) determinations, extracted from individual ratios at = 7 and 8 TeV, are combined, resulting in |f(LV)V(tb)| = 1.02 +/- 0.04 (meas.) +/- 0.02 (theo.). All combined measurements are consistent with their corresponding Standard Model predictions.Peer reviewe

STRENGTHENING CONCRETE HOLLOW SECTION GIRDER BRIDGE USING POLYURETHANE-CEMENT MATERIAL (PART B)

This paper presents experimental study to retrofitted reinforced concrete Hollow Section Bridge. The study was carried out on the White River Bridge structure (Bai xi da Qiao / China). The effect of retrofitting on stress and strain of beams at the critical section was studied. Evaluating the bridges girder after strengthening using new material called PolyurethaneCement material (PUC) as an external material .This study present the strain and deflection before and after strengthening the bridge girders. The results has shown that the overall state of the bridge structural strengthening is in good condition. The enhancement was significant in stiffness of the bridge structure. Regarding to the results of static load test, the experimental values strain and deflection are less than theoretical values, indicating that the stiffness of the structure, overall deformation and integrity satisfy the designed and standard requirements and the working performance are in good condition, and flexure capacity has a certain surplus

FINITE ELEMENT ANALYSIS OF DEEP BEAM UNDER DIRECT AND INDIRECT LOAD

This research study the effect of exist of opening in web of deep beam loaded directly and indirectly and the behavior of reinforced concrete deep beams without with and without web reinforcement, the opening size and shear span ratio (a/d) was constant. Nonlinear analysis using the finite element method with ANSYS software release 12.0 program was used to predict the ultimate load capacity and crack propagation for reinforced concrete deep beams with openings. The adopted beam models depend on experimental test program of reinforced concrete deep beam with and without openings and the finite element analysis result showed a good agreement with small amount of deference in ultimate beam capacity with (ANSYS) analysis and it was completely efficient to simulate the behavior of reinforced concrete deep beams. The mid-span deflection at ultimate applied load and inclined cracked were highly compatible with experimental results. The model with opening in the shear span shows a reduction in the load-carrying capacity of beam and adding the vertical stirrup has improve the capacity of ultimate beam load.http://dx.doi.org/10.30572/2018/kje/090212

Shear and Flexural Behavior of Flat Slabs Casted with Polyolefin Fiber-Reinforced Concrete

This paper presents the influence of polyolefin fiber on the flexural and shear attitude on the flat slabs. Three slab sets (80 cm × 80 cm) were tested, each with a thickness of 10 cm. In the first set (S1), the effect of fiber content on the flexural behavior of the flat slab was considered. Therefore, four slab specimens were cast, one of which was considered as a control specimen with no fiber content, while the other three included fibers at 0.5, 1, and 1.5 percent of the total concrete volume. The second series of experiments studied the flexural behavior of flat slabs (S2) with an opening of 15 cm × 15 cm. The first specimen contained nil polyolefin, while the second included 1% polyolefin. In the third set (S3), consideration was taken for 0 and 1% of Polyolefin to realize the shear behavior of the flat slab. The increase in polyolefin fiber content from 0 to 1.5% (for slab set 1) will decrease the deflection from 4.5 mm to 2.3 mm, with an average of 3.58 mm, which is close to the deflection of a 1% polyolefin fiber specimen. Three dimensional models for the tested slabs were simulated numerically via ABAQUS software program. The ratio of the maximum deflection between the experimental and the numerical outcomes were varied with a range of 1.01 to 1.28, with an average of 1.14