Computational Analysis of Reinforced Concrete Slabs Subjected to Impact Loads

Nowadays, the numerical models for the impact load assessment are starting to become more accurate and reliable. Combined with modern computer hardware, the computational time for such an assessment has been reduced to a satisfactory level. In this study, an attempt has been made to present the simulation technique and examine the accuracy of modern software with regards to assessing the response of reinforced concrete slabs subjected to impact loading near the ultimate load ranges. The response such as time-impact force graph, damage wave propagation, effectiveness of mesh density, effect of projectile size and final crack pattern are verified against existing experimental results. It is shown that the present general purpose Finite Element Analysis (FEA) is able to simulate and predict the impact behavior of structural systems satisfactorily

Finite element simulation of reinforced concrete slabs under impact loading

In a few years ago, efforts for assessing and predicting the behaviour of concrete structures subjected to impact loads have been hampered by lack of adequate computational procedure and unavailability of good quality experimental results. Furthermore, computer software was also not yet developed up to the standards of today. Nowadays, the numerical models for the impact load assessment are starting to become more accurate and reliable. Combined with modern computer hardware, the computational time for such an assessment has been reduced to a satisfactory level. In this study, an attempt has been made to examine the accuracy of modern software with regards to assessing the response of reinforced concrete slabs subjected to impact loading near the ultimate load ranges. The response such as Time-Impact force graph, damage wave propagation, failure process of steel reinforcement, effectiveness of mesh density, effect of projectile size and final crack pattern are verified against existing experimental results. It is shown that the present general purpose finite element software is able to simulate and predict the structural behaviour satisfactorily

Nonlinear Simulation of Beam Elements Subjected to High Mass Low Velocity Impact Loading using the Smoothed Particle Hydrodynamics (SPH) Method

In this paper, a fully Lagrangian method namely as Smoothed Particle Hydrodynamics (SPH) has been utilized in order to simulate the response of reinforced concrete beam subjected to low velocity impact loading. Models based on this method are proposed to capture an important failure mechanism on compression and tension of the beam elements under dynamic (impact) loading condition. Pressure dependant criterion known as Drucker-Prager (DP) with a new Plane-Cap (PC) yield surface were employed to concrete, and (Von-Mises) criterion was applied for steel reinforcement. The constitutive equation of PC model is employed on compression, while, orthotropic constitutive equation due to the damage effect is considered on tension. Meanwhile, Dynamic Increase Factor (DIF) was defined separately for the effect of strain rate (SR) on the concrete and steel reinforcement. Shear cracking, bending cracking and compressive behavior of the beam were evaluated by using displacement-time histories and overall failure mode. Then, the applicability and efficiency of the proposed models were validated with experimental tests through numerical simulations with different velocity (height of drop-mass)

Application of simple plane cap model to simulate compression failure of RC beam under impact loads

The aim of this paper is to present the non-linear analysis for impact response of reinforced concrete (RC) beam with prominence on tension and compression area. In order to envisage the RC behavior, pressure dependant yield criteria Drucker-Prager Plane-Cap (DPPC) type is assumed for the concrete, meanwhile, shear strain energy criterion Von-Mises (VM) is applied for steel reinforcement; to define the accurate strength of material during the short period (dynamic). These material models were incorporated with Adaptive Smoothed Particle Hydrodynamics (ASPH) method. Dynamic Increase Factor (DIF) has been employed for the effect of strain rate (SR) on the compression and tensile strength of the concrete; the orthotropic constitutive equation due to the damage effect is considered during the softening phase on tensile region while constitutive equation of cap model is employed on compression area. A series of experimental studies were also presented in this paper. Several beam elements were tested under low velocity impact loads. Failure mechanism such as shear cracking, bending cracking, compressive behavior of the beam were evaluated by using displacement-time histories as well as overall failure mode. Based on these studies, the investigations enabled a better understanding of the behavior of reinforced concrete beam elements under low velocity impact loads, as well as, it is confirmed that the proposed models give good agreement with experimental results

Evaluation of acid attack on concrete containing spent garnet as partial sand replacement

This research studied the water absorption of concrete containing spent garnet and determine the durability of concrete containing spent garnet in acidic environment. The materials used along the experiment works were spent garnet, river sand, crushed stone, ordinary Portland cement and water. In this study, spent garnet were used as sand replacement with 0%, 10%, 20%, 30% and 40% in concrete mix designs. First and foremost, the water absorption test was conducted on three (3) set of water-curing cube specimens with dimension 100 mm cube for the plain concrete and for each percentage of spent garnet concrete mixes and was done in compliance with the BS 1881: Part122 (1983) specification. After that, the durability tests under 5% of hydrochloric acid attack and 5 % of sulphuric acid attack were conducted by preparing corresponding sets of concrete specimens which were three (3) set of 28 days water-curing specimens for each percentage of spent garnet in different acid immersion according to Standard ASTM C1898 – 20 while the compressive strength was under standard in BS EN:12390-3: 2019. In the end of the study, the physical appearances of the samples were observed and the weight loss for each sample was tested and recorded accordingly. From the results obtained, the highest percentage of water absorption of concrete was C20 which was 7.80%. However, the stronger average concrete strength of concretes from both acids with the achieved target compressive strength was concrete C20 but also with lowest weight loss. The concrete containing with 20% of spent garnet had better acid resistant in terms of visual assessment not only toward sulphuric acid attack but also toward hydrochloric acid attack. The application of 20% of spent garnet as sand replacement was hence can provide stronger acid resistant in maintaining the supporting strength of concrete. In conclusion, the durability of normal concrete should be investigated over a longer length of time to mimic the real-world circumstance in which a structure is erected

Proceedings of the Sustainable Concrete Materials and Structures in Construction 2020

Seminar on Sustainable Concrete Materials and Structures in Concrete Construction 2020 was held virtually for the first time on 24 August 2020. This event was organized by the Faculty of Civil Engineering and Built Environment (FKAAB), Universiti Tun Hussein Onn Malaysia (UTHM) in collaboration with Concrete Society of Malaysia (CSM) and Civil Engineering and Built Environment Postgraduate Society, FKAAB (CiBPS). The theme of this seminar is Toward Sustainable Green Concrete. This seminar marks the first collaboration between these three organizations

Effects of spent garnet on the compressive and flexural strengths of concrete

Sand is the non-renewable resource which has been over-exploited from rivers in sync with the rapid development of construction industries to produce concrete. This affected the morphology of rivers and interrupted the functionality of riverine ecosystems by pollution. Meanwhile, the unrecyclable spent garnets were disposed of on a large scale and led to waste pollution. Therefore, this study aimed to determine the compressive and flexural strengths of concrete consisting of spent garnet as sand replacement. The specimens were prepared with consisting of spent garnet as sand replacement by weight in 0%, 10%, 20%, 30% and 40%. They were tested under compressive strength test at the age of 7 and 28 days while flexural strength test was conducted on the 28days. The findings revealed that the workability of fresh concrete was enhanced by an incremental amount of spent garnet. However, the compressive and flexural strengths of concrete consisting of spent garnet were discerned to be lower than control samples at all levels of replacement. Overall, the replacement with 20% spent garnet showed the optimum compressive and flexural strengths. It is concluded that the usage of spent garnet is considered as a promising resource for reducing consumption of sand and thus, improving the environmental problems

Numerical Homogenization of Protective Ceramic Composite Layers using the Hybrid Finite-Discrete Element Methods

Innovative technologies have resulted in more effective ceramic composite as high rate loading-resistance and protective layer. The ceramic composite layer consists of ceramic frontal plate that bonded by softer-strong reinforced polymer network, consequently gains the heterogeneous condition. These materials serve specific purposes of defeating high rate loading and maintaining the structural integrity of the layer. Further due to the lack of a constituent material and tedious problem in heterogonous material modelling, a numerical homogenization is employed to analyse the isotropic material properties of ceramic composite layer in homogenous manner. The objective of this study is to derive a constitutive law of the ceramic composite using the multi-scale analysis. Two-dimensional symmetric macrostructure of the ceramic composite was numerically modelled using the hybrid finite-discrete element method to investigate the effective material properties and strength profile. The macrostructure was modelled as brittle material with nonlinear material properties. The finite element method is incorporated with a Rankine-Rotating Crack approach and discrete element to model the fracture onset. The prescribed uniaxial and biaxial loadings were imposed along the free boundaries to create different deformations. Due to crack initiation on the macrostructure, the averaged stresses were calculated to plot the stress-strain curves and the effective yield stress surface. From the multi-scale analysis, the rate-dependency of Mohr-Coulomb constitutive law was derived for the ceramic composite layer

Performance of spent garnet as sand replacement in concrete at high temperature

Garnet is ideal for many commercial uses due to its potential to be recycled. The dumping millions of tons of spent garnet in landfills, quarries, oceans and waterways will cause the creating environmental concerns. In this study, spent garnet as a sand replacement is produced to innovate sustainable concrete. The research objectives are to study the effects of strength of spent garnet as sand replacement in concrete mix at high temperature and to evaluate its physical properties of spent garnet. Several laboratory experiments were conducted to determine the physical and its compressive strength before and after exposed to high temperature. Furthermore, the test for the physical properties that had been conducted were, specific gravity, bulk density and water absorption test. Other than that, the compressive strength of 30MPa at 28 days for trial mix design were prepared accordingly. The cube specimens of 100 × 100 × 100 mm were provided with substitution of 0%, 10%, 20%, 30% and 40% of spent garnet as sand replacement with 0.45 of water cement ration. All the concrete mixes containing spent garnet were produced slump of 30-60mm. Based on the test result, the cube specimen of 40 percent of spent garnet after heated started decrease in term of strength due to the present of the excessive of spent garnet particles in the concrete which can weaken the bond between aggregates and the cement paste. Thus, it reduces the concrete strength in term of less compaction of concrete has lower bonding strength

Computational impact responses of reinforced concrete slabs

The responses of reinforced concrete slabs subject to an impact loading near the ultimate load range are explored. The analysis is carried out on a simply supported rectangular reinforced concrete slab using a nonlinear explicit dynamic procedure and considering three material models: Drucker-Prager, modified Drucker-Prager, and concrete damaged plasticity, available in the commercial finite element software, ABAQUS/Explicit. For comparison purposes, the impact forcetime response, steel reinforcement failure, and concrete perforation pattern are verified against the existing experimental results. Also, the effectiveness of mesh density and damage wave propagation are studied independently. It is shown that the presently adopted finite element procedure is able to simulate and predict fairly accurate the behavior of reinforced concrete slab under impact load. More detailed investigations are however demanded for the justification of effects coming from an imperfect projectile orientation as well as the load and structural surface conditions, including the impulsive contacted state, which are inevitable in an actual impact environment