Blast And Ballistic Loading Of Structures

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Rational approach for predicting stress in beams with unbonded tendons

Aged structures and structures constructed based on outdated non-seismic design codes should be retrofitted to enhance their strength, ductility, and durability. This study evaluates the structural performance of reinforced concrete (RC) columns enhanced via polyurea or glass fiber reinforced polyurea (GFRPU) strengthening. Four RC column specimens, including a reference specimen (an unstrengthened column), were tested to evaluate the parameters of the strengthening materials and the strengthened area. The tests were carried out under a combined constant axial compressive load and quasi-static cyclic loading. The experimental results show that the composite strengthening provides lateral confinement to the columns and leads to enhanced ductility, shear-resistance capacity, and dissipated energy. The shear strength provided by the composites depends on the degree of lateral confinement achieved by the composite coating. The specimens finally failed through the development of diagonal tension cracks within the potential plastic hinge regions. The specimen treated with GFRPU strengthening showed greater strength and dissipated more energy than the specimen treated with polyurea strengthening. Furthermore, by modifying ATC-40, this study proposed an equation to estimate the shear capacity provided by the composites.

/pdf/shear-strength-of-reinforced-concrete-columns-retrofitted-by-22df6qahko.pdf

Shear Strength of Reinforced Concrete Columns Retrofitted by Glass Fiber Reinforced Polyurea

Equilibrium of shell structures

Penetration behaviour of TBM disc cutter assisted by vertical precutting free surfaces at various depths and confining pressures

https://iopscience.iop.org/article/10.1088/1757-899X/518/2/022057/pdf

A Review of Previous Studies on the Reinforced Concrete Corbels

Reinforcing struts and ties in concrete continuous deep beams

Optimization is a process through which the best possible values of design variables are achieved under the given of constraints and in accordance to a selected optimization objective function. Steel I-girders have been used widely in different fields, which are generally fabricated by connecting two plate flanges, a flat web and a series of longitudinal or transverse stiffeners together. The use of steel girder with external prestressing has been used in many countries as a means of strengthening bridges. The purpose of this paper is to develop a finite element model for the optimization of a steel girder with external prestressing. The ANSYS finite element software package was used to find the optimum cross section dimension for the steel girder. Two objective functions are considered in this study there are optimization of the strain energy and total volume of the girder. The design variables are the width of top flange, the thickness of top flange, the width of bottom flange, the thickness of bottom flange, the height of the web, the width of the web and area of prestressing tendons. Two type of steel girder are considered there are steel girder without prestressing and steel girder with prestressing. The results for volume minimization shows that the optimum cross section for steel girder with prestressing smaller than for steel girder without prestressing.

/pdf/finite-element-analysis-and-optimization-of-steel-girders-3445nkiit2.pdf

Finite Element Analysis and Optimization of Steel Girders with External Prestressing

Post-Tensioned (PT) method is a widely used technique to prevent cracking and to minimize the deflection which is resulted by loads. In this method, stress is applied after concrete placing and reach adequate hardening and strength. This paper investigates the structural behaviour of PT two-way concrete slabs. The main objective of this study involves a detailed flexural behavior analytical investigation of PT concrete two-way slab with the different bonded tendon layout. This will be achieved by non-linear Finite Element (FE) analysis programs method, to choose the most effective and optimum position of tendon layout with different number of tendons and applied load on the concrete two-way slab. A parametric study was conducted to investigate the effect of tendons layout on the overall behavior of post-tensioned two-way concrete slab. The result obtained from finite element analysis showed that the failure load in PT in both directions increased about 89 % as compared with slab PT in one direction.

/pdf/finite-element-modeling-of-post-tensioned-two-way-concrete-1hyleahekd.pdf

Finite Element Modeling of Post-Tensioned Two-Way Concrete Slabs under Flexural Loading

Most codes of practice, like ACI 318-14, 9.9.1.3, require the use of strut-and-tie modeling (STM) to deal with reinforced concrete continuous deep beams (rc-cdbs). Though, investigations that conducted on rc-cdbs did not include all the most influential parameters. This work presents an analytical parametric study using STM stated by ACI 318-14 to calculate load capacity of 20 rc-cdbs with different parameters. The parameters took into consideration in the current work are shear span to overall depth ratio (a/h), width of beam (bw), width of bearing plate (BP), concrete compressive strength (f’c) and amount of vertical shear web reinforcement (pv). It is seen that the load capacity decreases by about 14% to 37% when a/h increases by about 33% to 100%. It is also seen that load capacity increases by about 33% to 100% when bw increases by about 33% to 100%, while the load capacity increases by about 10% to 30% when BP increases by about 33% to 100%. Finally, it is found that load capacity increases by about 35% to 100% when compressive strength increases by about 35% to 100%, while the load capacity increases by about 0% to 25% when pv increases by about 33% to 100%.

Khattab Saleem Abdul-Razzaq

Papers

A Review of Previous Studies on the Reinforced Concrete Corbels

Reinforcing struts and ties in concrete continuous deep beams

Finite Element Analysis and Optimization of Steel Girders with External Prestressing

Finite Element Modeling of Post-Tensioned Two-Way Concrete Slabs under Flexural Loading

Reinforced concrete continuous deep beams under the effect of different parameters