Analysis and Design of RC Chimney in STAAD-PRO

Reinforced chimneys are used in Power plants to take the hot and poisonous flue gas to a great height designed mainly to resist the lateral forces like wind and earthquake as well the thermal stresses of the flue gas. An attempt is made to understand the variation of lateral deflection at the top of the chimney, by varying the height of chimney above 275 m. A total of five models are selected for five different heights i.e 275m, 285m, 295m, 305m & 315m and the analysis is done. All the models were analyzed and the lateral deflection regarding is calculated. Code of practice for design of reinforced concrete chimney (Third revision of IS 4998:1992 [Part I]) is used for the referance analysis. STAAD PRO software is used to do the analysis. Further an attempt is made to understand the variation of lateral deflection at the top of the chimney for different heights.

Does Self-Compacting Concrete Exert more Pressure on Formworks than Normal Vibrated Flowing Concrete?

This paper investigates lateral pressure on formwork indirectly by measuring lateral deflection using an innovative device. This device is fabricated from Polyvinyl Chloride (PVC) cylindrical mold in a fashion allowing occurrence and measurement of lateral movement at different depths using dial gauges. The lateral deflections for different systems of filling materials including water, sand, self-compacting concrete (SCC), and flowing concrete. The flowing concrete is tested under two conditions, vibrated (NVC), and non-vibrated (NCno.V). The results show that the NVC produced the largest lateral deflection which attributed to the vibration pressure. The measured lateral deflection are ranked descending in the following order: NVC, Water, SCC, NCno.V and Sand.

Numerical Assessment of Lateral Deflection Equation of Single-Storey Light-Frame Wood Shearwalls

Based on the decomposition of the deflection into bending, panel shear, nail slip, and base rotation terms, the nonlinear four-term equation specified by the Canadian wood design code provides an estimate of the total lateral deflection of light-frame wood shear walls. This paper reports the creation of a numerical procedure for separating the responses for each term using a detailed nonlinear finite element modeling (FEM) that simulates individual components of shear walls. Since sheathing panel stiffness is not considered in computations of the bending term, the study reveals that bending deformation results calculated using the equation are more conservative than the FEM results. The nail slip term does not reflect the real nail base connection properties. A new equilibrium equation for determining the lateral deflection due to base rotation is presented. The equation is generally conservative because of the omission of some practical considerations.

Development of compressive testing device for glass fiber based single face corrugated structure sheet, and estimation of buckling strength of straight panel of that structure sheet

<abstract> <p>This work aims to reveal the in-plane-compressive characteristics of Glass Fibre based single face corrugated Structure Sheet (GFSS) by developing a loading holder of the both ends of the panel of GFSS in the direction of the cross machine direction. A grooved end-support device was developed and exmined. In order to set stably and quickly a straight panel of GFSS on the compressive-testing apparatus, the width and the depth of the holder's groove were varied against the geometrical size of the panel, and the stability and reproducibility of compressive deformation of the panel was experimentally investigated. When changing the height of the panel and reinforcing the both ends of the panel by dipping instant adhesives, the deformation behavior and the buckling strength was characterized in three modes: a short height crushing without lateral deflection, a small lateral deflection mode as the intermediate state, and a triangle-like folding as a long height crushing.</p> </abstract>

Assessing the Dynamic Behaviour of Midrise Frame Structures Sitting on Silty Sandy Soil

Background: Midrise 5 to 15 storeys frame structures sitting on soft soils are susceptible to damage induced by seismic events. The level of damage is related to the interaction between the structure, foundation and soil called Soil Structure Interaction (SSI). If the level of ground acceleration is low, the wave gets amplified putting the structure at risk of collapse. Objective and Methods: Concerns about SSI have motivated several researchers to investigate the seismic behaviour of structures rested on cohesive and cohesionless soils. The objective of the work presented in this paper is to evaluate the effects of several parameters on the seismic soil structure interaction behaviour of midrise structures sitting on silty sandy soil. Using ABAQUS, reliable 3D models of 5 to 15 storeys midrise concrete frame structures rested on raft foundation were built. The effects of the structure’s number of storeys, raft size and thickness were explored for different column sizes. Fixed-based structures which capture the model adopted in seismic codes and flexible-based structures were hit at the bottom by El-Centro (1940) and Northridge (1994) earthquakes. Results and Conclusion: The results, presented in terms of storey lateral deflection, inter-storey drift, shear force, foundation rocking and response spectrum showed the important contribution of SSI effects on the behaviour of the midrise structures. The model analyses indicated that column size strongly affects the behaviour of flexible structures. Let N be the structure number of storeys and C the column size. The results showed that in terms of storey lateral deflection and levelling shear force, for column sizes C 0.5 X 0.5 m, SSI was detrimental to structures with 10 ≤ N ≤ 15 and beneficial to structures with 5 ≤ N <10. Increasing the column size to C 0.5 X 1 m showed that SSI became detrimental for structures with 10 < N ≤ 15 under El-Centro (1940) and for structures with 7≤ N ≤ 15 under Northridge (1994), and beneficial for structures with 5 ≤ N ≤ 10 under El-Centro (1940) and for structures with 5 ≤ N < 7 under Northridge (1994). The FE results showed that even though base shear increased with raft size, lateral deflections were amplified for C 0.5 X 0.5 m S15 structures and attenuated for C 0.5 X 1 m S15 structures. However, the seismic response of S15 structures was slightly affected by the variation in raft thickness under both column sizes. Finally, the paper includes a discussion and evaluation of the contribution of inertial and kinematic effects, including soil types used on the simulated numerical models’ seismic responses.

Mathematical Modelling and Dynamic Analysis of an Offshore Drilling Riser

In this paper, a dynamic model of an offshore drilling riser is developed based on the Hamilton principle. The developed dynamic model is transformed into a finite element model by introducing an approximate solution which chooses the Hermite cubic interpolation function of bending beam element as the shape function. Thereafter, the standard Newmark integration is applied to numerically simulate the dynamic responses of offshore drilling risers with varied system parameters, including the length of riser, top tension ratio, and buoyant factor. Based on the results of numerical simulation, under the influences of sea wind, sea current, and the periodic excitation of sea wave, the offshore drilling riser experiences a fast lateral deflection phase in the beginning, a reciprocating deflection phase in the following long duration, and then, a periodic oscillation when it reaches the dynamic stable condition, respectively. The riser system working in deeper water with a higher top tension ratio and a lower buoyant factor shows more controllable vibration and less lateral deflection.