Static load test

Most blast door manufacturers opt to perform static load tests on prototype assemblies of low-range blast doors to demonstrate that the assembly will resist the blast overpressure specified. Static tests should be accepted only if the dynamic structural response and dynamic load factors have been considered and the door, frame, and restraining hardware are manufactured using the same materials, dimensions, and tolerances as those in the prototype static test. 

The universally aeeepted method for testing adhesion under shear is a static load test [21], where a known surfaee area of the adhesive-coated product is applied under controlled... 

While a static load test is the commonly accepted procedure, in practice many variations in areas and weights are used, to compensate for the various qualities of adhesive evaluated, so that the test results will fall into a similar time frame, so it becomes difficult to compare different adhesive systems from accumulated data. It has the disadvantage of giving variable results for the same adhesive system, and is essentially a pass/ fail test, as many products remain in place at the end of the test period. Experience has shown that the shear properties of pressure-sensitive adhesives to porous and nonporous substrates can be quite different, and each must be judged on its own merits. 

Maximization of the load-bearing behaviour of these tubes can be achieved by external reinforcement, consisting of composites (see Fig. 10.5). In the experiments a woven fabric of fibreglass, as well as of carbon fibre, was used, which was laminated with epoxy resin. Static load tests have proved that the new material has significant better characteristics than normal wood, especially if the weight is taken into consideration. Within the areas of connections failures could be observed, which can be avoided by partial fortification of the reinforcement [30,31]. 

Full-scale static load test on prototype foundations. 

In this chapter we will describe the methods of estimating the load carrying capacity of piles using the analytical and dynamic methods, based on the dynamics of pile driving. The full-scale static load test and dynamic methods based on wave propagation will be described in another chapter of the book. 

At sites where a full-scale load test is not available (such as for small projects), pile driving formulas may be used to access the static load carrying capacity of driven piles. Each pile has a required load capacity that corresponds to a certain minimum acceptable blow count. Therefore the pile is driven until it reaches the specific blow count (refusal). In large projects where static load test is usually carried out, tiie pile driving formulas may be modified to match the load test results. This custom formula is then applied to other piles at the site, and thus provides a mean of extrapolating the load test results, and for purposes of construction control. 

A precise way to determine the ultimate axial (as well as pull out) of deep foundations is to build a full-size prototype foundation at the site of the proposed foundation and slowly load it to failure. This method is known as static load test. Static load tests are generally much more expensive and time-consuming, and thus must be used judiciously. 

The objective of a static load test is to develop a load-settlement curve or, in the case of uplift tests, a load-heave curve. This curve is then used to determine the ultimate load capacity. 

Figure 11.1. Use of a hydraulic jack reacting against dead weight to develop the test load in a static load test.

To conduct a static load test, there must be a means of applying the desired loads to the foundation and measuring the resulting settlement. The most common method is the kentlegde system whereby dead weights such as precast concrete blocks are stacked on top of the foundation, as shown in Figure 11.1. An alternative is to provide multiple support in the form of reaction pile and use them as a reaction for a hydraulic jack (Figure 11.2). 

From the load-settlement curve obtained from the static load test, the ultimate load capacity of the pile can be determined. This, however, requires where the failure occurs to be defined, i.e. for cases that do not exhibit a clear plunging failure. Various methods are available to estimate the ultimate pile capacity such as Chin s (1970) method and Davisson s (1973) method. 

Chin (2004) presents results of a static load test on a 825 mm diameter drilled shaft and assessed it with regard to the relevant settlement acceptance criteria of Table 11.1. The Malaysian PWD specification for piling works was adopted as the standard specification governing the testing and foundation pile performance. 

Osterberg (1984) developed a method that reduces the cost of conducting high capacity static load tests, in particular for the drilled shafts, as shown in Figure 11.6. Once the concrete is in place, the operator pumps hydraulic fluid into the jack and keeps track of both pressure and volume. The jack expands and pushes up on the shaft. A dial gauge measures this movement, from which a plot of side friction capacity versus axial movement can be obtained. The devise also includes a telltale rod that extends from the bottom of the pancake jack to the ground surface. It measures the downward movement at the bottom, and thus produces a plot of toe-bearing pressure versus axial movement. 

This Case method computations include an empirical correlation factor, that can be determined from the static load test. Thus, engineers can use this method to extend static load test results to selected production piles. However, for most projects, it would not be cost-effective to obtain PDA measurements on all of the production piles. 

To produce simulated static load test results. 

CAPWAP analyses can be used to reduce the required number of static load tests, or used where load tests are not cost-effective. 

Comparison of test results of high strain dynamic testing with static load test... 

Figure 11.9. Comparison of pile axial load capacity from static load test (SLT) and high strain dynamic pile testing (HSDPT) (from Liew et al. 2004).

Static load testing remains the most reliable technique for assessing single pile performance. Such testing should be started early in the construction program to verify that both the design and construction are satisfactory. 

EN 15416-2 2008, Adhesives for load bearing timber structures — Test methods — Part 2 Static load test of multiple bondfine specimens in compression shear. 

For example, single-lap shear joints can have a known static load applied, then inserted into a specified environment, and the time-to-failnie of joints noted as a function of variables such as adhesive type, pre-treatment and stress (see Shear tests). Static loads can also be applied to other joint configurations. Many studies have shown that such tests exhibit good discrimination between different surface pre-treatments. The creep performance of adhesives can also be measured by means of static load testing (see Durability creep rupture and Durability sub-critical debonding). 

All of above computer methods are similar to the loaded process of static load testing, and the ultimate loads are estimated on the load-displacement curves of computations. Because the physical model of soils is different from the objective condition of... 

The ultimate loads of pile, which were assessed by the static load test of pile, strength reduction method of FEM and increment load method of FEM, were given in Table 3. The limit condition of... 

Part 2 Static load test of multiple bond line specimens in compression shear. 

Young s modulus should therefore be calculated adequately with either Eq. (1) or (2) according to the context. Materials discussed in this chapter generally undergo static loading and thus elasticity of materials will be defined as the slope of the stress-strain curve resulting from a uniaxial static loading test, as defined in Eq. (1). 

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