Shear Performance Assessment of Timber Log-House Walls under In-Plane Lateral Loads via Numerical and Analytical Modelling

Abstract

Log-house is an ancient construction technology based on the superposition of linear timber logs, connected to the orthogonal walls by a system of carvings, notches and corner joints. Due to the fact that this solution is widely used in constructions located in seismic or windy areas, the in-plane behaviour of walls represents an attractive research topic. In this paper, major outcomes of a Finite-Element (FE) numerical investigation carried out on single corner joints currently in use for log-house buildings are discussed under different loading conditions (i.e., in-plane lateral and vertical compressive loads), including parametric analyses to capture the key aspects of their typical structural response. Careful consideration is paid for the elastic stiffness of such joints, being of primary interest for design purposed. At the same time, a linear analytical formulation is presented, with the aim of providing a simple but useful tool in support of design, and especially to estimate the maximum lateral displacement/resistance for a given log-house wall when subjected to in-plane lateral forces. There, the intrinsic mechanical features of corner joints and related aspects are properly considered (i.e., static friction phenomena, as well as the presence of small gaps, etc.). The analytical model, in addition, takes advantage of the numerically predicted joint stiffness values, being dependent on several parameters. As shown, rather good agreement is obtained between the FE model output, the analytical predictions and past reference experimental/numerical results available in the literature for full-scale log-house walls under in-plane lateral loads, hence suggesting the potential of the proposed approach. In conclusion, possible Force-Preload-Displacement (FPD) charts are presented, to act as simplified tools for preliminary design considerations.

Experimental investigation of lateral resisting elements for the wood polyvinyl chloride composite log‐house under in‐plane lateral loads

“…Numerous researchers have studied these lateral resisting elements. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Firstly, various handcrafted notch geometries of corner joints (e.g., Saddle, Norwegian, Daimon, and Dovetail notch) were proposed and their performance was investigated under in-plane lateral loads. [7][8][9] Then, the lateral load resistance of the standard half lapped, and dovetail corner joints of modern log houses were examined via experiments, [10,12,13] numerical methods, [12][13][14][15] and analytical methods.…”

“…[7][8][9] Then, the lateral load resistance of the standard half lapped, and dovetail corner joints of modern log houses were examined via experiments, [10,12,13] numerical methods, [12][13][14][15] and analytical methods. [16] In addition, the two main types of LF connections were investigated, including a sill log element on various floor types [7,17,18] and angle brackets. [10,11] In the case of log-log friction, the friction coefficients under various vertical loads and sliding characteristics between timber log layers were studied experimentally, [12,19] and it was found that the sliding characteristic between layers of log elements could not be included in the lateral load resistance prediction [10] because of its sensitivity to various parameters.…”

Structural Vulnerability Assessment of Heritage Timber Buildings: A Methodological Proposal

“…A simplified hybrid method has been presented for nonlinear FEM, particularly for timber frame buildings, such that the elements are modelled using the experimental testing results from the substructures [100]. Hybrid simulation has been utilized to investigate the seismic vulnerability of timber frame buildings [101][102][103][104][105][106][107][108][109], and then developed for numerical simulation of log houses [110][111][112][113][114][115] and post and beam structures [116][117][118][119][120][121].…”

Fire Resistance of In-Plane Compressed Log-House Timber Walls with Partial Thermal Insulation

“…The governing material strength was assumed equal to the compressive resistance of spruce in the direction perpendicular to the grain, with f c,90 = 3.57 MPa the mean value. Spruce anisotropy was then accounted, in terms of resistance values, in the form of Hill plastic law (see [26,27]). The material density at 20 • C was finally set to the nominal value of 420 kg/m 3 .…”

“…This is the case of traditional structural solutions like log-house (or log-haus, or Blockhaus) systems that are not specifically considered by design codes (see for example [20,21]), particularly in fire conditions [22]. So far, research studies have been focused on their structural performance under various loading configurations, including seismic events [23][24][25][26][27], buckling [28] and thermal exposure [29].…”