Theoretical and experimental evaluation of timber-framed partitions under lateral drift

This paper identifies the inherent strengths/weaknesses of rigid timber-framed partitions and quantifies the onset drifts for different damage thresholds under bi-directional seismic actions. It reports construction and quasi-static lateral cyclic testing of a multi-winged timber-framed partition wall specimen with details typical of New Zealand construction practice. Furthermore, the cyclic performance of the tested rigid timber-framed partition wall is also compared with that of similar partition walls incorporating ‘partly-sliding’ connectiondetails, and ‘seismic gaps’, previously tested under the same test setup. Based on the experimentally recorded cyclic performance measures, theoretical equations proposed/derived in the literature to predict the ultimate strength, initial stiffness, and drift capacity of different damage states are scrutinized, and some equations are updated in order to alleviate identified possible shortcomings. These theoretical estimates are then validated with the experimental results. It is found that the equations can reasonably predict the initial stiffness and ultimate shear strength of the partitions, as well as the onset-driftscorresponding to the screw damage and diagonal buckling failure mode of the plasterboard. The predicted bi-linear curve is also found to approximate the backbone curve of the tested partition wall sensibly.

Experimental study on bond strength of joint surface of double-sided laminated shear wall

In order to study the bonding strength of the joint surface of the double-sided laminated shear wall, a double-sided laminated shear wall specimen was designed and fabricated, and then the the bars were planted in the precast layer and the middle post pouring layer of the specimen, and the normal tensile bond strength of the joint surface was tested by the drilling core planting bar drawing method. The results show that the bond strength of the joint surface of double-sided laminated shear wall can be detected by the method of drilling core planting bar drawing, and according to the cross section of the core sample, it can be known that the joint surface is indeed the weak part of the laminated member, and it is suggested that the bond strength of the joint surface of the double-sided laminated shear wall should be tested by planting steel bars in the middle post-cast layer.

Experimental study on seismic performance of new reinforced tenon joint precast shear walls

The seismic performance of the precast shear wall was improved by using a newly developed reinforced tenon to strengthen the precast joint, which is used to bear the shear force of the precast joint and reduce the effect of dowel action on the vertical connecting steel bars. The vertical connecting steel bars were only used to bear tensile and compressive stress and consume seismic energy. The seismic performance of reinforced tenon precast shear wall was investigated by quasi-static tests on one reinforced tenon precast shear wall specimen and one ordinary flat seam precast shear wall specimen. This study investigated the crack distribution and failure modes, precast joint slip of the two specimens, and the seismic performance parameters such as bearing capacity, stiffness degradation, ductility performance and energy dissipation capacity. The test results demonstrated that the reinforced tenon effectively reduced the slip of the joint surface and exhibited good ductility and energy dissipation capacity than that of the ordinary flat seam specimen, while the failure mode, bearing capacity, and stiffness were similar to that of the flat seam specimen.

Fire behaviour of ecological soil–cement blocks with waste incorporation: Experimental and numerical analysis

The main goal of this study is to assess the behaviour of soil–cement blocks with incorporation of organic wastes. The problem of waste accumulation exists worldwide and has become a concern in today’s society, leading to enormous environmental damage. One of the possibilities for reducing their environmental impact is the reuse of these wastes in new materials. However, incorporating waste changes the mechanical, physical and thermal properties of the new material. In order to evaluate the potential use of waste in blocks composition, laboratory tests were conducted and the results were analysed. This article presents the fire behaviour of ecological soil–cement blocks with waste incorporation. Therefore, an experimental programme was performed using samples of wall panel with soil–cement blocks. The wall specimen under fire conditions was also analysed by a non-linear transient finite element numerical model, in time and temperature domains, and the numerical and experimental temperature fields were compared.

Study on Seismic Behavior of Steel Frame-Steel Shear Wall with Assembled Two-Side Connections

Low-cycle reciprocating loading tests were carried out on a steel frame with prefabricated beam-only connected steel plate shear wall (specimen A) and a steel frame with welded beam-only connected steel plate shear wall (specimen B). The seismic performance of the two different types of steel frame-steel plate shear wall specimens was studied and the failure modes, hysteresis curve, skeleton curve, and seismic performance index, etc of two groups of specimens were obtained, together with the studies of failure characteristics, ductility, energy dissipation, and stiffness degradation of the two specimens. The results showed that the assembled steel frame-steel plate shear wall with connection joints of steel shear wall with discontinuous cover plate connected on both sides (DCPC) have good seismic performance. On the basis of no loss of seismic performance, DCPC joints can provide better energy dissipation capacity than traditional welded steel plate shear wall structures and ensure the good postearthquake repair function.

Behaviour of Horizontal Connections in Precast Walls under Lateral Loading

The design of connections is one of the most important considerations in the structural design of precast concrete structures. The purpose of the connection is to transfer loads, restrain movement and provide stability. Within one joint there may be several load transfers, each one must be designed for adequate strength and ductility and appropriately detailed. The proposed investigation aims to achieve efficient horizontal connections in precast walls with improved structural performance under various loads. HYSD reinforcement dowels are used as connectors. The arrangement of dowels is varied to achieve the efficient load transfer in the walls. The experimental investigation on three precast wall and one monolithic wall depicts that the precast wall exhibits high strength than the monolithic wall specimen and structural performance were found to be better than the monolithic wall specimen and also the efficient load transfer is achieved in the precast wall

Development and Testing of a Friction/Sliding Connection to Improve the Seismic Performance of Gypsum Partition Walls

Observed earthquake damage, laboratory tests, and loss analyses have shown gypsum partition walls to be susceptible to earthquake damage under small story drift ratios, which can result in large losses under design earthquake ground motions. To mitigate this risk, a new friction/sliding connection is proposed that can minimize or prevent damage to partition walls for story drift ratios of 1% or more. The proposed friction/sliding connection isolates the partition wall from the structure while providing sufficient resistance to support out-of-plane forces on the wall induced by inertial effects. Test results of three prototype connections and two full-scale wall partition specimens, with and without the friction connection detail, are summarized to demonstrate the improved performance that can be achieved with the proposed friction/sliding connection. Whereas the test of the conventional wall specimen began experiencing damage at 0.1 to 0.3% story drift ratio, the wall specimen with the connection could undergo drifts up to about 1.5% without any damage.

Experimental study on seismic performance of a low-energy consumption composite wall structure of a pre-fabricated lightweight steel frame

This study developed a low-energy consumption composite wall structure constructed with a pre-fabricated lightweight steel frame that is suitable for houses in villages and towns and evaluated its anti-seismic performance. A low-reversed cyclic-loading test was conducted on four full-scale pre-fabricated structure specimens, including a lightweight, concrete-filled steel tube (CFST) column frame specimen (abbreviated as SFCF), a lightweight CFST column frame composite wall specimen (abbreviated as SFCFW), an H-steel column frame specimen (abbreviated as HSCF) and an H-steel column frame composite wall specimen (abbreviated as HSCFW). The failure characteristics, hysteretic behaviour, strength, rigidity, ductility and energy dissipation capacity of each specimen were compared and analysed. The results demonstrated that the pre-fabricated, double L-shaped beam–column joint with a stiffener rib which was proposed in this study worked reliably and exhibited good anti-seismic performance. The yield, ultimate and frame yield loads of the specimen SFCFW were 1.72, 1.80 and 2.03 times higher than those of specimen SFCF. The yield load, ultimate load and frame yield loads of specimen HSCFW were 1.27, 1.68 and 1.82 times higher than those of specimen HSCF. This indicates that the embedded composite wall contributed significantly to the horizontal bearing capacities of the SFCF and HSCF specimens. The embedded composite wall was divided into multiple strip-shaped composite panels during failure and achieved a stable support for the frame in the later stages of elastoplastic deformation. The horizontal strips of the tongue-and-groove connection between the strip-shaped composite panels produced reciprocating bite displacements, and ultimately improved the structure's energy dissipation capacity significantly.

Prevalence of Porphyromonas gingivalis fimbriae A genotypes II and IV in patients with chronic periodontitis and atherosclerosis

Background. Atherosclerosis is known as one of the chronic diseases with high prevalence in the human species. Many studies have elucidated the relationship between this disease and chronic periodontitis caused by Porphyromonas gingivalis (P.g). The aim of this study was to investigate the prevalence of P.g fimbriae A (fimA) genotypes II and IV in patients with periodontitis and atherosclerosis. Methods. This cross-sectional study investigated the frequency of P.g II and IV genotypes in the subgingival plaque specimens of 42 subjects in three experimental groups: periodontitis (A), atherosclerosis (B), periodontitis + atherosclerosis (C) and aortic wall specimens obtained from 30 patients (groups B and C) by the PCR technique. Results. P.g bacterium was seen in 46.6% of patients with chronic periodontitis. The same bacterium was not found in aortic wall specimens of patients with chronic periodontitis (group C) and there was only one P.g-positive aortic wall specimen (7.7%) among the patients with healthy periodontium (group B). Genotypes II and IV were not observed in any specimen. Conclusion. The results of statistical analysis showed no significant correlation between the prevalence of P.g and genotypes II and IV in the subgingival plaques and the incidence and severity of atherosclerosis.

The Role of Ozonized Erythrocytic Mass Transfusion in the Restoration of Myocardial Morphological Changes during Blood Loss (Experimental Study)

Purpose.To evaluate the role of ozonized erythrocytic mass transfusion in the restoration of damages in the architectonics of myocardium microvasculature and cardiomyocytes in case of a severe blood loss.Materials and Methods. Two batches of experiments were conducted, 17 white outbred rats in each. The animals were anesthetized with thiopental sodium (25 mg/kg). Blood loss was caused by taking 3ml of blood from the tail artery of rats, which is 35% of the circulating blood volume. One hour after the blood loss, transfusion of autoerythrocytes with normal saline solution and Ringer’s solution infusion in 1:1 ratio was performed in the control batch. In the experimental batch, 3 ml of autoerythrocytes treated with ozonized saline solution with ozone concentration of 2 mg/l and 3 ml of Ringer’s solution (1:1 ratio) were administered to rats. Erythrocyte mass was prepared from 3 ml of the autoblood harvested from the animals 3 days before the experiment. On a post-transfusion day5, in both batches and in five intact animals, hearts were removed following the intraperitoneal thiopental sodium injection (100 mg/kg). The left ventricle wall specimen from each heart was removed for examination. Histologic sections were stained with hematoxylin and eosin. The preparations were visually examined and morphometric studies were performed using microvisor Vizo-103.Results.It has been established that administration of ozonized erythrocyte for severe blood loss correction limited the decrease in numbers of capillary profiles and their diameters, formation of mixed and hyaline thrombi fully or partially occluding microvascular lumens, major hemorrhages and reduction of variation of nuclear profiles, decreased perivascular, pericellular, perinuclear, and endonuclear edema of myocardial tissue, cardiomyocyte overcontruction zone, and their ruptures.Conclusion.The positive trends for microcirculation indices, vascularization density and myocardial edematization as prognostic markers in assessing potential posthypoxic rehabilitation of damaged tissues upon blood loss correction with ozonized erythrocyte mass might be explained by the antihypoxic, antioxidant, and detoxifying actions of ozone on erythrocytes and/or its metabolites (ozonides) in the body post-transfusion.