scholarly journals Seismic Performance of Lightweight Concrete Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Swamy Nadh Vandanapu ◽  
Muthumani Krishnamurthy
Keyword(s):  
Lightweight Concrete ◽  
Concrete Structures ◽  
Normal Weight ◽  
Bending Moments ◽  
Structural Members ◽  
Dead Load ◽  
Reinforced Concrete Frame ◽  
Shear Forces ◽  
Concrete Frame ◽  
Standard Software

Concrete structures are prone to earthquake due to mass of the structures. The primary use of structural lightweight concrete (SLWC) is to reduce the dead load of a concrete structure, which allows the structural designer to reduce the size of the structural members like beam, column, and footings which results in reduction of earthquake forces on the structure. This paper attempts to predict the seismic response of a six-storied reinforced concrete frame with the use of lightweight concrete. A well-designed six-storey example is taken for study. The structure is modelled with standard software, and analysis is carried out with normal weight and lightweight concrete. Bending moments and shear forces are considered for both NWC and LWC, and it is observed that bending moments and shear forces are reduced to 15 and 20 percent, respectively, in LWC. The density difference observed was 28% lower when compared NWC to LWC. Assuming that the section and reinforcements are not revised due to use of LWC, one can expect large margin over and above MCE (maximum considered earthquake; IS 1893-2016), which is a desirable seismic resistance feature in important structures.

scholarly journals Effect of Variation in Moisture Content on Soil Deformation and Differential Settlement of Frame Structures in Nairobi Area and its Environs

2021 ◽  
Vol 15 (1) ◽  
pp. 106-128
Author(s):  
Hannah N. Ngugi ◽  
Stanley M. Shitote ◽  
Nathaniel Ambassah
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Differential Settlement ◽  
Frame Structure ◽  
Bending Moments ◽  
Soil Deformation ◽  
Reinforced Concrete Frame ◽  
Shear Forces ◽  
Concrete Frame

Background: The stability of structures to a great extent depends on the foundation. The foundation of a building structure plays a key role in transferring the loading from the structure to the soil underneath. In foundation design, the effect of changes in soil moisture content to soil deformation and subsequent differential settlement during the lifespan of a structure is often ignored. Objective: This research establishes the relationship between soil moisture content and soil deformation for soils in the Nairobi area and its environs. Soil deformation in some foundation supports in a building leads to an unequal settlement resulting in differential settlement. The research further determines the influence of soil deformation on the differential settlement of a typical four-storey reinforced concrete frame structure. Methods: Seven soil samples collected from the Nairobi area and its environs were subjected to moisture content variation. Soil deformation was measured, and the laboratory test results were applied to determine the modulus of subgrade reaction constant for the elastic foundation. A four-storey reinforced concrete frame structure was modelled at varying foundation conditions. The resulting differential settlement for frame structure was evaluated. Two control cases were assessed. The structural behaviour depicted by changes in bending moments, shear forces, differential settlement, and member stresses for varying foundation cases was assessed. Staad Pro software was applied in structural modelling. Results: Increasing soil moisture content from 30% to 50% and 75% by keeping all other factors constant led to increased soil deformation ranging from 17.2% to 34% for the 7 soil samples tested. Structural modelling revealed that increasing soil moisture content at a group of four outer footings in a 16 footings’ building contributes to significant changes in shear forces, bending moments, compressive and tensile stresses, and supports the differential settlement. Differential settlement induced by soil deformation arising from an increase in soil moisture content from 30% to 75% increased by 49.1%. Conclusion: Increase in soil moisture content contributed to soil deformation, which led to a significant differential settlement in a line of foundation’s outer footings in a building. The moisture content-caused differential settlement, which contributed to remarkable changes in the amount and distribution pattern for shear forces, bending moments, compressive and tensile stresses, and node displacement when the soil moisture content was increased from 30% to 75%.An increase in soil moisture content to 50% and above at some footings of a building would lead to structural failure unless the building structure is specifically designed to withstand such differential settlement. Construction stakeholders should consider the differential settlement attributed to variation in soil moisture content during the structure’s lifespan and safety factors adequately at the design stage to avoid potential structural failure and even collapse.

Numerical Analysis for Progressive Collapse of a Multi-Storey Building due to an Explosion in its Basement

2011 ◽  
Vol 250-253 ◽  
pp. 3115-3119 ◽  
Author(s):  
Li Tian ◽  
Hao Wang
Keyword(s):  
Numerical Analysis ◽  
Progressive Collapse ◽  
Simulation Method ◽  
Structural Members ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Whole Process ◽  
Main Work ◽  
Storey Building

A numerical analysis for the progressive collapse of a reinforced concrete frame caused by an explosion in this structure’s basement is presented in this paper. The whole process from the detonation of the explosive charge to the complete demolition is reproduced. The main work is focused on the role of soil in structural collapse and failure mode of structural members. The analysis is simulated using ANSYS/LS-DYNA and proposes a new simulation method which is comparatively accurate and economic.

scholarly journals The influence of OPC and PPC on compressive strength of ALWA concrete

2018 ◽  
Vol 195 ◽  
pp. 01021
Author(s):  
Fedya Diajeng Aryani ◽  
Tavio ◽  
I Gusti Putu Raka ◽  
Puryanto
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Normal Weight ◽  
Structural Members ◽  
Concrete Composition ◽  
Normal Weight Concrete ◽  
To Come ◽  
Seismic Forces

Lightweight concrete is one of the options used in construction in lieu of the traditional normal-weight concrete. Due to its lightweight, it provides lighter structural members and thus, it reduces the total weight of the structures. The reduction in weight resulting in the reduction of the seismic forces since its density is less than 1840 kg/m3. Among all of the concrete constituents, coarse aggregate takes the highest portion of the concrete composition. To produce the lightweight characteristics, it requires innovation on the coarse aggregate to come up with low density of concrete. One possible way is to introduce the use of the artificial lightweight aggregate (ALWA). This study proposes the use of polystyrene as the main ingredient to form the ALWA. The ALWA concrete in the study also used two types of Portland cements, i.e. OPC and PPC. The ALWA introduced in the concrete comprises various percentages, namely 0%, 15%, 50%, and 100% replacement to the coarse aggregate by volume. From the results of the study, it can be found that the compressive strength and the modulus of elasticity of concrete decreased with the increase of the percentage of the ALWA used to replace the natural coarse aggregate.

Seismic response of reinforced concrete frame subassemblages — a Canadian code perspective

1989 ◽  
Vol 16 (5) ◽  
pp. 627-649 ◽  
Author(s):  
Patrick Paultre ◽  
Daniel Castele ◽  
Suzanne Rattray ◽  
Denis Mitchell
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Concrete Structures ◽  
Poor Performance ◽  
Reinforced Concrete Beam ◽  
Test Results ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Slab Width ◽  
Cyclic Loading Tests

The 1984 CSA standard for the design of concrete structures for buildings provided new seismic design and detailing requirements for concrete structures. Full-scale, reversed cyclic loading tests of reinforced concrete beam–slab–column subassemblages were carried out to investigate the seismic performance of frame structures designed with the latest Canadian code. The test results indicate the importance of including the influence of slab reinforcement in computing the beam capacity as well as the need to carefully design the joint regions for shear. The test results indicate the excellent performance of frame components designed with K = 0.7 (R = 4.0) and the poor performance of those designed and detailed with K = 2.0 (R = 1.5). The performance of subassemblages designed with K = 1.3 (R = 2.0) depends on the column to beam strength ratio and on the shear strength of the joints. Models to predict the flexural response as well as the shear response of key elements are described and the role of the spandrel beam in limiting the effective slab width is explained. Key words: seismic design, reinforced concrete, detailing, structures, codes.

Study on Damage Identification for Reinforced Concrete Structures Based on Wavelet Transform

2011 ◽  
Vol 94-96 ◽  
pp. 1505-1510 ◽  
Author(s):  
Xiao Yu Miao ◽  
She Liang Wang ◽  
Yu Jiang Fan
Keyword(s):  
Wavelet Transform ◽  
Reinforced Concrete ◽  
Damage Identification ◽  
Concrete Structures ◽  
Spatial Location ◽  
Reinforced Concrete Structures ◽  
Test Model ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Reinforced Concrete Frame Structures

Reinforced concrete structures are prone to damage during their service lifetime caused by factors such as the effect of overload, ground motions, and other actions. Undetected damage may lead to structural failures. Early detection of damage and timely repairs can prevent catastrophic failure and ensure regular service of structures. As a result, a so-called delimitation wavelet-transform search method, based on the characteristic of multi-resolution of wavelet transform, is presented in this paper for on-line damage identification of reinforced concrete structures. One possible advantage of this method is that the damage temporal and spatial location can be detected rapidly and efficiently. Further research is carried out with numerical simulation of a structure test model to study the storied damage detection and localization of reinforced concrete frame structures under seismic actions. The analyzing result is compared with that observed in a simulated earthquake vibration stand test. Good agreement is obtained and it verifies the effectiveness and validity of the method proposed in this paper.

Strengthening and Retrofitting of the Industries Building After Fires

2013 ◽  
Vol 671-674 ◽  
pp. 778-781 ◽  
Author(s):  
Ming Liu ◽  
Xin Hai Fan ◽  
Yong Zhi Zuo ◽  
Bao Feng Song
Keyword(s):  
Reinforced Concrete ◽  
Frame Structure ◽  
Structural Members ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Damage Degree ◽  
Reinforced Concrete Frame Structure ◽  
Building Area ◽  
Polymer Mortar ◽  
Structural Mode

The reinforcement project is three-storey of the industries building, the total height of the industries building is 14,200mm, the clear height of one storey is 7,500mm, the building area is 1,500 square meters, structural mode is reinforced concrete frame structure. The structural members were damaged seriously due to fire In January 2010, strengthening the damaged members was proposed in order to ensure the safety of the structure. Enlarging section reinforcement method, Polymer Mortar and gluing CFRP methods were adopt to strengthen the beams, columns and floor slab depending on the damage degree of the concrete member.The idea of dealing with the industries building damaged by fire can provide us a good reference of repairing the similar industries building.

scholarly journals Finite Element Analysis of I-Girder Bridge

2021 ◽  
Vol 9 (8) ◽  
pp. 2084-2097
Author(s):  
Mohd Nadeem
Keyword(s):  
Prestressed Concrete ◽  
Concrete Bridge ◽  
Bending Moments ◽  
Railway Bridge ◽  
Dead Load ◽  
Shear Forces ◽  
Bending Resistance ◽  
Girder Bridge ◽  
Deck Slab

Abstract: In India railway bridge structures are widely designed with the method suggested by IRS – Concrete bridge code 1997.This Code of Practice applies to the use of plain, reinforced and prestressed concrete in railway bridge construction. It covers both in-situ construction and manufacture of precast units. The Code gives detailed specifications for materials and workmanship for concrete, reinforcement and prestressing tendons used in the construction of railway bridges. After defining the loads, forces and their combinations and requirements for the limit state design, particular recommendations are given for plain concrete, reinforced concrete and prestressed concrete bridge construction. The design of I-Girder bridge superstructure (deck slab and PSC I-beam) are done by calculating bending moments, shear forces, bending resistance in transverse direction, bending resistance in longitudinal direction, checking flexural cracking. The Design of PSC I-Girders is done for Bending moments and Shear forces by Dead Load, Super Imposed Dead Load (SIDL) and Live Loads (LL). The Shrinkage strain, Creep Strain and effect of Temperature rise and fall are also determined. The design is complete for Pre-stressing cables, un-tensioned reinforcements, End cross girder, Shear connectors. I-girder superstructures are the most commonly used superstructures at cross-over location in metro bridges in india, as it has the wide deck slab and it easily permits metro’s to change tracks. I-Girder superstructure construction is component wise construction unlike U-Girders. I-Girders are constructed in casting yard and its deck slab is cast in situ, parapets are also installed on later stage. Keywords: SIDL effects, Live Load effects, Derailment effect, with or without 15% future PT margin

scholarly journals Influence of effective width of flange on calculation and reinforcement dimensioning of beam of reinforced concrete frame

2021 ◽  
Vol 20 (2) ◽  
pp. 041-056
Author(s):  
Maciej Tomasz Solarczyk
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Frame ◽  
Cross Sectional ◽  
Concrete Frame ◽  
Definition Of ◽  
Effective Flange Width ◽  
The Impact ◽  
T Beam

The article analyses the impact of modeling the cross-section of two-nave and two-storey reinforced concrete frame with dimensions: 18.0 m × 32.0 m as a bars on the results of bending moments, the value of elastic deflection and dimensioning of reinforcement due to bending. Six options were considered: a beam as a rectangular section and five T-beam variants with different definition of effective flange width. The differences in obtained results were commented. Conclusions useful for the designing of reinforced concrete structures were presented. The procedure for determining the effective flange width in the context of PN-EN 1992-1-1:2008 and PN-B 03264:2002 standards with a commentary on the use of effective flange width in calculations and construction of reinforcement in reinforced concrete structures were described. Brief description of determining the reinforcement due to bending according to simplified method given in PN-EN 1992-1-1:2008 was presented. In addition, the standard formula for determining the minimum cross sectional area of reinforcement (9.1N) in PN-EN 1992-1-1:2008 with a proposal for its strict determination for the T-beam with a flange in the tensile zone was analyzed.

Torsion of Reinforced Concrete Structural Members

2018 ◽  
Vol 272 ◽  
pp. 178-184
Author(s):  
Vladimír Křístek ◽  
Jaroslav Průša ◽  
Jan L. Vítek
Keyword(s):  
Bending Moments ◽  
Structural Elements ◽  
Structural Members ◽  
Structural System ◽  
Shear Forces ◽  
Axial Forces ◽  
Methods Of Calculation ◽  
Tensile Forces ◽  
Torque Capacity ◽  
The Common

According to the common design methods of calculation of the stress state induced by torsion of massive prismatic concrete structural elements, the structural system is reduced to a simple cage consisting of ties and struts. This model has, however, a number of principal shortcomings, the major of them is the fact that all of simultaneously acting effects like axial forces, bending moments and shear forces are not taken into account – the compressive axial forces increase very significantly the torque capacity of structural members, while due to action of tensile forces, bending moments and shear forces the torque capacity is reduced. These phenomena, applying non-linear approaches, are analysed and assessed.

Risk of Thermal Cracking from Use of Lightweight Aggregate in Mass Concrete

2017 ◽  
Vol 2629 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Aravind Tankasala ◽  
Anton K. Schindler ◽  
Kyle A. Riding
Keyword(s):  
Cross Sections ◽  
Lightweight Concrete ◽  
Coefficient Of Thermal Expansion ◽  
Concrete Structures ◽  
Lightweight Aggregate ◽  
Thermal Cracking ◽  
Normal Weight ◽  
Mass Concrete ◽  
Normal Weight Concrete ◽  
Cracking Risk

This paper describes the results of a numerical investigation of incorporating lightweight aggregate (LWA) in mass concrete structures. Numerical simulation was performed with ConcreteWorks software on three rectangular piers for normal weight concrete, internally cured concrete, sand–lightweight concrete, and all–lightweight concrete. Results show that temperature differences greater than 35°F may not necessarily introduce thermal cracking in mass concrete made with LWA. Maximum core temperatures and temperature differences increased with decreasing concrete density; however, the cracking risk of the mass concrete elements decreased as a greater quantity of LWA was used, regardless of element size. This trend occurred because other properties, such as coefficient of thermal expansion, creep, modulus of elasticity, tensile strength, and geometrical conditions, influenced the risk of thermal cracking. Additionally, the identification of the cross-section locations involved in measuring the critical temperature difference in a mass concrete structure are presented. The results of this work can be helpful in identifying critical stress locations in cross sections and assessing the cracking risk for mass concrete structures. A temperature and stress analysis is recommended before mass concrete construction involving LWA is begun.

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