Behavior of mortarless wall subjected to in-plane combine loading

The ability of mortarless wall to restrain/sustain lateral load become important aspect to be consider in the design of wall. Therefore, this paper presents analyses of mortarless wall subjected to in-plane combined loading using finite element programs. The developed 2D finite element program is used in this research. The finite element models are developed based on micro modelling approach where each constituent of masonry (block and dry joint) connected each other by joints at their actual position. Eight nodded isoparametric plane element and six nodded zero thickness isoparametric interface element are used to represent block unit and dry joint respectively. The developed models are analysed under nonlinear environment. The most relevant results concern the strength response of the dry joint masonry walls subjected to in-plane combined compressive and shear loading. The results of finite element analysis compared with corresponding experimental results and its show good agreement. Parametric study also performed to consider the important parameters that effect the design of wall under combined loading. Significant features of the structural behaviour, ultimate capacity and observed failure mechanisms are addressed and discussed

Hydration of the combinations of ground granulated blast furnace slag cements

The heat of hydration is known as a measurement of the initial chemical reactions for the hydration of cement. The heat liberated during the hydration process affects the temperature rise in concrete, which may cause an early-age thermal cracking of a concrete structure. To address this thermal cracking issue, Portland cement/ground granulated blast furnace slag (PC/GGBS) is often used, due to the low heat hydration properties of GGBS. This paper presents the results of isothermal conduction calorimetry tests performed on GGBS binary cement, Portland cement/ground granulated blast furnace slag (PC/GGBS), GGBS ternary cement, and Portland cement/ground granulated blast furnace slag/metakaolin (PC/GGBS/MK). The tests covered a range of GGBS levels, which are up to 75% GGBS level and up to 15% MK content by mass for the ternary cement combinations. For PC/GGBS cement, the total heat of hydration is lower than that of PC, and an increase in the GGBS levels resulted in a decrease in the amount of heat liberated; however, for PC/GGBS/MK, the heat of hydration generated is lower than that of PC but is greater than those of the equivalent PC/GGBS, which has an equivalent PC content

Effect of tropical climate to compressive strength of high performance fibre reinforced concrete

High performance fibre reinforced concrete (HPFRC) is relatively an advance fibre reinforced concrete (FRC) material, which is made of more than 2% volume fraction of fibres. This research focuses on the effect of tropical climate on the compressive strength of HPFRC. Total of 56 HPFRC cubes made of 3%, 4% and 5% of hooked-end fibres and grade 80 slurry were prepared. Half of which were exposed to tropical climate condition (80% humidity at 35°C) for 30 days which the other half are placed in room temperature. After which, the compression test was carried out. The highest compressive strength of 152.2 MPa was recorded from samples made of 5% fibre volume and being exposed to tropical climate, which is 90% higher than the control sample

Effect of flexible soil in seismic hazard assessment for structural design in Kuala Lumpur

Kuala Lumpur, Malaysia, is considered to be safe against an earthquake threat. However, tremors felt by occupants due to long distance earthquakes from Sumatra has raised concern on building safety in this region. Consequently, Malaysia will adopt the Eurocode 8 for seismic design. The suitability of this code must be studied especially on the threat from far field earthquakes. Thus, site specific hazard assessment has been conducted on seven flexible soil sites in Kuala Lumpur, based on modified time history. The peak ground acceleration (PGA) falls in the category of very low seismicity, however, the amplifications are much higher than recommended by Eurocode 8. The period limits for maximum accelerations are also much higher compared to the value in the code, especially for flexible soils. Adoption of Eurocode 8 for seismic design in this region should be studied to include the effects of high period motions in flexible soils, especially on the amplification factors and its corner periods

Site specific seismic hazard assessment for Kuala Lumpur and vicinity from long distance earthquakes

Earthquake motion on a building is dependent upon its underlying soil. A proper site specific hazard assessment is necessary for safe design of structures especially on flexible soil. Kuala Lumpur and Selangor is considered to be safe against earthquake threat. However, more tremors are being felt by occupants due to long distance earthquakes from Sumatra, raises concern on the safety of the buildings in this region. Previous studies on flexible soil in Singapore discovered that the amplification due to soil resonance could be up to 12 times higher than the motion on rock. To validate this, site specific hazard assessment has been conducted on six sites in Kuala Lumpur and Selangor areas. The analysis is based on modified time history and using one-dimensional ground response analysis. The soil amplifications are found to be much higher than the values recommended by Eurocode 8. The adoption of Eurocode 8 for seismic design in this region should be carefully done by taking into account the effect of long distance earthquake to the wave propagation in flexible soil

Finite element analysis of proposed self-locking joint for modular steel structures

The intermodular connection between modules plays a vital role in the overall performance of modular structures. The separation between a column and connection is possible due to the absence of links (welding or bolting) since limited space is available between modules. This study proposed a self-locking joint to be used in a modular steel structure, connecting columns with a connection without need of extra space between modules. The behavior of the proposed connection subjected to monotonic load was evaluated using a finite element approach using ABAQUS software. The influencing factors contributed to the behavior of the self-locking connection and columns observed using a parametric study. The parametric study was conducted by varying beam thickness, bolt pretension force and friction coefficient µ. Results indicate that the proposed connection can be classified as a semirigid connection according to Eurocode 3 and special moment frame (SMF) as recommended by AISC

Structural behavior of mortarless interlocking load bearing hollow block wall panel under out-of-plane loading.

Experimental and numerical investigation of interlocking mortarless wall panels with 1.0 m height, 1.2 m width and 150 mm thickness are conducted. Behaviour of both hollow and partially grouted masonry wall panels is studied. The panels were tested under constant pre-compressive vertical load and out-of-plane lateral load. Lateral load carrying capacity, deflection at mid height, dry joint opening between block layers and mode of failure are investigated. Strain characteristics throughout the loading process are also monitored. A finite element analysis is presented for the system and a good agreement between the experimental and modelling results is achieved. Parametric study using the finite element model is also presented and the effect of different parameters; amount of pre-compressive load and slenderness ratio is studied. The study reveals that pre-compressive vertical load and reinforcement significantly affect the structural behaviour of mortarless walls under out-of-plane loading. Useful expressions for the capacity are obtained from the analysis

Response of precast foamed concrete sandwich panels to flexural loading

This paper presents the results of an experimental and analytical investigation of a total of six precast foamed concrete sandwich panels (PFCSPs) as one-way acting slabs tested under flexural loads. Foamed concrete of 25.73 MPa was used to produce the PFCSP concrete wythes. The results obtained from the tests have been discussed in terms of ultimate flexural strength capacity, moment-vertical deflection profile, load–strain relationship, strain variation across the slab depth, influence of aspect ratio, cracking patterns, and ultimate flexural load at failure. An analytical study of finite element analysis (FEA) as a one-way slab model was then conducted. The increase in aspect ratio (L/d) from 18.33 to 26.67 shows a reduction of 50% and 69.6% on the ultimate flexural strength capacity as obtained experimentally and in FEA models, respectively. Theoretical analyses on the extremes of fully composite and non-composite actions were also determined. The experimental results showed that cracking patterns were observed in one direction only, similar to those reported on a reinforced concrete solid slab, as well as precast concrete sandwich panels, when both concrete wythes act in a single composite manner. The experimental results were compared with FEA model data, and a significant degree of accuracy was obtained. Therefore, the PFCSP slab can serve as an alternative to the normal concrete slab system in buildings

Structural behavior of axially loaded precast foamed concrete sandwich panels

This paper presents results from an experimental and analytical study of precast foamed concrete sandwich panels (PFCSPs). Full-scale experimental tests of six PFCSPs were conducted to study the behavior of the panels under axial loads. Foamed concrete (FC) was used to cast PFCSP concrete wythes. The axial load-bearing capacity, load–deflection profiles, load–strain relationships, slenderness ratio, load–displacement, load–deformation, failure and collapse modes, cracking patterns, and propagations under constant increments of axial loads were recorded and discussed. The properties and use of FC were briefly reviewed. Results of the experimental test and finite element analysis were compared with the theoretical values calculated based on the American Concrete Institute (ACI) design equation for a solid concrete wall and other empirical formulas developed by antecedent researchers which might be applicable to predict the ultimate load-bearing capacity of sandwich panels. A semi-empirical formula was proposed based on the laboratory test and finite element analysis results

Evaluation of the compatibility of modified encapsulated sodium silicate for self-healing of cementitious composites

Healing agent carriers play a significant role in defining the performance of the autonomous self-healing system. Particularly, the ability to survive during the mixing process and the release of the healing agent when cracks occur without affecting the mechanical properties of the cementitious composite. Up to now, these issues are still a concern since glass capsules are unable to survive the mixing process, while some types of microcapsules were reported to cause a decrement in strength as well as limited strength recovery. Therefore, this study was twofold, addressing the surface treatment of polystyrene (PS) capsules and the evaluation of the compatibility of the modified capsules for cement-based applications. Secondly, assessing the healing performance of modified PS capsules in cementitious composites. Furthermore, the study also evaluates the potential healing performance due to the synergic effect between the encapsulation method and the autogenous self-healing mechanism. The investigation was carried out by measuring the changes in the pH of pore solution, FTIR analysis, survival ratio, and bonding strength. For self-healing assessment, the compression cracks on the cement paste were created at an early age and the strength recovery was measured at the age of 28 and 56 days. To identify the chemical compounds responsible for the healing process, SEM-EDX tests were conducted. Moreover, the effect of silica fume (SF) on bonding strength and self-healing was also evaluated. Based on the results, the modified PS capsules by roughing approach showed promising performance in terms of survivability, bonding, and recovery. The modified PS capsule increased the strength recovery by about 12.5–15% for 100%OPC and 95%OPC + 5%SF, respectively. The finding observed that the combining of modified PS capsules and the inclusion of SF gave high strength recovery of about 20% compared to 100%OPC without capsules. Thus, the modified PS capsule has a good potential for self-healing of cementitious-based applications