Analysis of Rectangular Reinforced Concrete Liquied Tanks by Using Yield Line Theory

In the analysis of rectangular reinforced liquid storage tanks, a method assuming linear-elastic behavior for material can be used, i.e., the strip method, the moment coefficient method, the finite element method, etc. In the analysis of these types of tanks, tank walls can be considered as slabs. In this study, tank walls were analyzed as slabs subjected to hydrostatic loading; in the analysis, the yield line theory is used because it is more suitable for the linear inelastic behavior of reinforced concrete slabs than the ones based on the linear elastic theory. An iterative algorithm based on yield line theory is presented for the design of isotropically reinforced recrangular concrete slabs supported along all four edges. A computer program is coded which predicts the location of yield lines for the slabs depending upon certain parameters. As a result of this prediction, the manual design of such slabs can be significantly simplified by the use of the coefficient obtained by using the program. It was shown that the analytical computation of the ultimate moment per unit length requires the solution of a highly nonlinear system of equations. This difficulty was overcome by utilizing an iterative technique within the computer program. It also gives the value of the ultimate moment per unit length of the yield line.

Comparison of Modified Yield-Line and Punching Shear Capacities for Concrete Traffic Barriers and Bridge Rails

The traditional, triangular yield-line method used by most departments of transportation for analyzing concrete traffic barriers and bridge rails has been largely unchanged since 1978. Testing of concrete barriers since this time has indicated that the triangular yield-line method is not qualitatively representative of observed damage patterns and is overconservative. Further, the conversion from NCHRP Report 350 to the crash test criteria from the Manual for Assessing Safety Hardware (MASH) will result in increases to lateral impact loads; therefore, overconservative analysis practices may result in many concrete barriers being unnecessarily deemed inadequate. In this research, alternative analysis methods for concrete barriers were extracted from an extensive literature review of concrete barrier investigations. These methods were applied to a sample of eight concrete barriers to demonstrate and compare their effects on capacity estimates. Alternative methods included trapezoidal yield-line mechanisms, effects of impact heights lower than the top of the barrier, punching shear evaluation, and consideration of expected material strengths. Capacity estimates of the selected barriers were increased by an average of 47 percent when alternative methods were cumulatively applied. Although the traditional method does not consider punching shear, the capacity of one of the eight barriers was controlled by punching shear rather than by yield-line flexure. With the alternative methods applied, seven of the eight barriers were deemed adequate relative to the increased lateral loads corresponding to MASH criteria for Test Levels 2 through 5. By contrast, if analyzed according to the traditional method, three of the eight barriers would have been deemed insufficient considering MASH loads.

A comparative study on yield line mechanisms for four bolted extended end-plated connection

Extended end-plated connections are preferred in moment resisting frames due to their advantages such as no required in-situ welding, accurate fabrication and economic feasibility compared to flange welded moment connections. The capacity of the extended end-plated connections depends on bolt configurations, end-plate thickness, bolt diameter and their material properties excluding column part. The thickness of end-plate can be computed using yield line mechanisms. Different yield line patterns are available in the literature and some of these are adopted in seismic codes to estimate the thickness of end-plate. In this study, the accuracy of different yield line patterns is compared using collected experimental data and numerical analysis. A parametric numerical analysis was conducted utilizing the finite element tool, ABAQUS. The results of experimental data and parametric study were evaluated for both unstiffened and stiffened four bolted extended end-plated connections. The results revealed that the capacity of the end-plate connections significantly depends on the yield line mechanism. Therefore, selecting an accurate yield line mechanism is essential in order not to overestimate the thickness of the end-plate. More importantly is that these yield line mechanisms can be directly implemented to AISC 358 and Turkish Building Earthquake Code 2018 (TBEC-2018).

Development of innovative designs of bridge barrier system incorporating reinforcing steel or GFRP bars

In harsh environment, corrosion of steel reinforcement causes durability problems. Glass Fiber Reinforced Polymer (GFRP) has emerged as an alternative to corrosion-related problem of steel bars in development of sustainable bridge deck and barrier walls. The current research program has been divided into five phases. In phase I, an extensive study has been conducted on pullout strength and bond behavior of pre-installed GFRP bars into concrete slabs and concrete cubes. In phase II, based on the Canadian Highway Bridge Design Code (CHBDC) factored applied moment at deck-wall junction, three configurations of GFRP-reinforced barrier detailing, using High-Modulus (HM) and Standard-Modulus (SM) GRFP bars, were proposed. The proposed barriers were tested by constructing five actual-size, 1.0-m long, PL-3 barrier models to determine their ultimate load carrying capacities and failure modes. In phase III, a full-scale PL-3 barrier made of GFRP-HM bars, with headed-end anchors as connecting bars to the deck slab, was constructed and tested under transverse static loading at both interior and exterior locations to-collapse to determine its crack pattern, failure mode and static ultimate load carrying capacity. In phase IV, from the trapezoidal failure pattern observed during testing the GFRP-reinforced PL-3 barriers, the research program was extended to revisit the triangular yield-line failure patterns in steel-reinforced PL-2 and PL-3 barriers specified in AASHTO-LRFD specifications. Experimental static tests to-collapse were conducted on constructed actual-size PL-2 and PL-3 steel-reinforced barriers, leading to more accurate expressions for their transverse load capacities developed based on the yield-line theory. In phase V, non-linear finite element analysis was conducted on GFRP-reinforced bridge barriers tested in phase III. The finite-element modeling was conducted to solely simulate the experimental test results for future research. A good agreement between experimental observations and numerical finite-element modeling was observed. Finally, this research led to (i) a more accurate design procedure for the GFRP - and steel-reinforced barrier wall and the barrier-deck joint, and (ii) design tables for the applied moment and tensile forces to be used to design the deck slab and the barrier deck-junction to resist transverse loading resulting from vehicle impact.

Development of innovative designs of bridge barrier system incorporating reinforcing steel or GFRP bars

In harsh environment, corrosion of steel reinforcement causes durability problems. Glass Fiber Reinforced Polymer (GFRP) has emerged as an alternative to corrosion-related problem of steel bars in development of sustainable bridge deck and barrier walls. The current research program has been divided into five phases. In phase I, an extensive study has been conducted on pullout strength and bond behavior of pre-installed GFRP bars into concrete slabs and concrete cubes. In phase II, based on the Canadian Highway Bridge Design Code (CHBDC) factored applied moment at deck-wall junction, three configurations of GFRP-reinforced barrier detailing, using High-Modulus (HM) and Standard-Modulus (SM) GRFP bars, were proposed. The proposed barriers were tested by constructing five actual-size, 1.0-m long, PL-3 barrier models to determine their ultimate load carrying capacities and failure modes. In phase III, a full-scale PL-3 barrier made of GFRP-HM bars, with headed-end anchors as connecting bars to the deck slab, was constructed and tested under transverse static loading at both interior and exterior locations to-collapse to determine its crack pattern, failure mode and static ultimate load carrying capacity. In phase IV, from the trapezoidal failure pattern observed during testing the GFRP-reinforced PL-3 barriers, the research program was extended to revisit the triangular yield-line failure patterns in steel-reinforced PL-2 and PL-3 barriers specified in AASHTO-LRFD specifications. Experimental static tests to-collapse were conducted on constructed actual-size PL-2 and PL-3 steel-reinforced barriers, leading to more accurate expressions for their transverse load capacities developed based on the yield-line theory. In phase V, non-linear finite element analysis was conducted on GFRP-reinforced bridge barriers tested in phase III. The finite-element modeling was conducted to solely simulate the experimental test results for future research. A good agreement between experimental observations and numerical finite-element modeling was observed. Finally, this research led to (i) a more accurate design procedure for the GFRP - and steel-reinforced barrier wall and the barrier-deck joint, and (ii) design tables for the applied moment and tensile forces to be used to design the deck slab and the barrier deck-junction to resist transverse loading resulting from vehicle impact.